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Rust and Corrosion in Electrical Panels, A Study and Report on Frequency and Cause
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The reported observations include corroded, burned, and damaged connections and corroded and malfunctioning circuit breakers. Causative factors noted in the service environment include presence of moisture, damage from overcurrent, and poor installation practices. Suggested improvements, including the need for greater resistance to corrosion and other field and environmental conditions, are discussed. -- This material was first presented at the October 1991 IEEE-Holm Conference on Electrical Contacts. Original text expanded by the author for this online publication 20 February-March 2006. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use the links at page left to navigate this document or to go to Other Website Topics. Green links at left show where you are in our document & website.

INTRODUCTION - Rust and Corrosion in Electrical Panels - Field Observations of Residential Service Panel Connections and Components

IEEE Holm Conference on Electrical Contacts, Daniel Friedman, Poughkeepsie, NY, October 19, 1992

Introduction to the Electrical Panel Corrosion Study

Visual examination of the electrical service equipment is an important element of the procedure followed by professional home inspectors, whose observations are most often made at the time of sale of a used residence. These observations can provide a data base of field performance of residential electrical system components that may be valuable for the development of improvements in both the components and their associated qualification standards.

Professional home inspectors offer a unique perspective on field failures: in performing a comprehensive survey of a building's systems and components, an inspector may discover common external or interactive causes of damage or deterioration. Inspectors see in-service field conditions, often before failures occur, and before failing conditions are so obvious as to come to the attention of the occupants. Other studies of connector/component failures in service panels have focused on defects discovered after rather than before actual failures and have not considered corrosion/damage diagnosis based on a comprehensive examination of the entire structure and site for causal factors. (1)(2)(3)(4)

1052 Electric Service Panels were examined in the field, in conditions of actual use. Examination revealed frequent occurrences of corroded, burned, and damaged connections and corroded and malfunctioning circuit breakers. Significant, reportable corrosion/related defects in the panels were observed in 12% of cases - a frequency significantly greater than that anticipated by the electrical industry. Causative factors noted in the service environment included presence of moisture, damage from overcurrent, and poor installation practices. Suggested improvements, including the need for greater resistance to corrosion and other field and environmental conditions, are discussed. This information was first presented to industry experts at the 1992 Philadelphia IEEE Holm Conference on Electrical Contacts to suggest that the moisture and corrosion resistance characteristics of electrical panels and their contents should be increased. Information about the common causes and sources of water entry was also of importance to home inspectors who need to be alert for these conditions and for the damage and risks they may cause.

PANEL PHOTO LIST - List of Illustrations of Electrical Panel Corrosion

The original illustrations and photos, available by clicking on the links below, are called-out in the article text by individual [Figure #].

• External electrical panel rust, is a clue indicating that water is likely to have entered or condensed in this electrical panel [Fig. 0] - inspectors should be extra cautious when opening an electric panel where external rust is visible
• External electrical panel rust at the breaker knockouts, is a further clue indicating that water is likely to have entered or condensed in this main electrical panel[Fig. 0a] - watch for in-panel corrosion
• Corroded neutral/grounding bus, water in bottom of the electrical panel [Fig. 1] - this is reportable neutral bus and enclosure base corrosion.
• Severe rust on circuit breaker and electrical connectors in electrical panel [Fig. 2]
• Common corroded ground connectors with evidence of overheating [Fig. 3]
• Severe Rust on steel neutral/ground bus in electrical panel, corroding neutral wires [Fig. 4]
• Water runs inside Electrical Service Entry Cable (SEC) in electrical panel [Fig. 5]
• Frayed SEC, poor seal at top of electric meter box [Fig. 6]
• Opening in house wall at Electrical Service Entry Cable (SEC) lets water run into building by capillary action [Fig. 7]
• Wet basement wall at service panel creates conditions conducive to high interior moisture, condensation, and corrosion in the electrical panel [Fig-8]
• Uniform condensation in the electric panel caused by wet basement conditions, contrasted with actual water leaks into the panel. Condensation will wet most in-panel surfaces uniformly and cause a more-even rust distribution in the panel rather than causing very rusty spots at the panel bottom and along the drip pathway from the point of water entry. The overheating at one of the shared-neutral circuit wires here may be due to another problem in the building. [Fig-9]
• Water drips in panel - new equipment with the old leak remaining - old panel failed, was replaced, but leak source was not corrected, water entering inside the SEC plastic covering. [Fig-10]
• Corroded neutral bus in the electric service panel [Fig-11]
• Rusty electrical service panel, overheating equipment [Fig-12]
• Very rusty old electrical fuse panel, connectors ok - copper - some older equipment tolerated leaks better than more modern electric panels and circuit breakers [Fig-13]
• Sketch of common direct water entry points which admit water into the electrical equipment at a building [Fig-14]
• Overheated electrical branch circuit wires may or may not be due to failure of a corroded circuit breaker to trip on overcurrent [Fig-15]
• Water tracks behind main bus are visible below the bottom of the column of circuit breakers in this badly rusted electrical panel [Fig-16]

PANEL RUST STUDY PROCEDURE - Study Procedurefor Electrical Panel Corrosion

Comprehensive visual inspections for building defects were performed on 1052 private homes between 1987 and 1991. The overhead service drop, service entrance conductors, electric meter, and raceway or cable from the electric meter to the service panel were examined, as were the service panel and all components therein. Inspection was visual, did not normally involve use of test equipment, and followed well established guidelines for professional home inspectors.(5)(6)(7).

Field notes were recorded indicating any defects in each panel. Site conditions which might be a related cause were also noted. Every "defect" was severe enough to merit a report to the building owner or buyer as a safety concern.

Visible damage or other conditions which might indicate malfunction or unsafe conditions included: significant rust or corrosion on any component; signs of overheating [Such as [Fig-3] overheated electrical ground and neutral wires at a corroded panel bus, and [Fig-15] overheated electrical branch circuit wires which may or may not be due to a corroded circuit breaker which failed to trip], or other damage at connections of the service entrance wires, at wiring connections on circuit breaker terminals or individual fuse terminals, at neutral or ground bus bars or connectors; or rust at the base of the panel enclosure itself. Light surface rust on the exterior of the panel or minor corrosion in the panel interior were not reported if there were no other indications of malfunction such as evidence of overheating or of past repair work.

The field data were tabulated: estimated year of equipment installation, system ampacity, panel type (breaker, fuse, antiquated), presence of knob-and-tube wiring, presence of rust or corrosion on four common locations in the panel, apparent source of moisture related to corrosion, and other defects (mis-wired device, burned connectors, etc.).

PANEL RUST STUDY RESULTS - for Electrical Panel Corrosion

Frequency of Corrosion in Electric Panels

An examination of field notes from more than a thousand private home inspections performed between 1987 and 1991 reveals rust and corrosion of various electrical components in 126 of 1052 service panels. More than one in ten service panels showed sufficient corrosion to merit, in the opinion of the inspector, report to the client of a possible safety or functional concern with the equipment. The age of equipment varied from brand new to more than 50 years old. [Table 1]. Most of these were circuit-breaker type panels (835), with the remainder fused equipment (217). More than one in ten service panels showed sufficient corrosion to merit a report to the client of a concern.[Table 2].

The criteria for reporting such damage in a given panel is subjective, not quantitative, and does not normally involve equipment tests. Two definitions of severity of damage are:

Light corrosion: surface rust spots on panel enclosure parts or on other steel components in the panel. No visible evidence of failure, wet components, arcing, burning, history of repairs, or other clues suggesting, from external visual inspection, that safety components such as fuses or circuit breakers appear at likely risk of malfunction. Light corrosion instances were not tabulated in this study.

Serious corrosion: heavy rusting or other corrosion at connections of the service entrance wires (usually at terminals on a main fuse block or circuit breaker), at wiring connections on circuit breaker terminals or individual fuse terminals, at neutral or ground bus bars or connectors, or at the base of the panel enclosure itself. Exfoliation on steel panel components, or other highly-suspect conditions are present in such cases.

Even if the inspector does not observe serious corrosion on wiring connections in a panel equipped with circuit breakers, the presence of heavy rust, exfoliation, or actual water in the panel enclosure is considered grounds for reporting a serious finding. This conclusion is based on an untested opinion of many professional inspectors that the presence of sufficient moisture to cause such corrosion raises questions about the condition of hidden safety components such as circuit breaker internal parts or bus-bar components covered by breakers or fuses.

The natural collection point for moisture, the panel bottom, might be reached after droplets have passed over and in some cases through other electrical components and connectors.

Rust on steel service panel components was by far the most common observation, occurring in 110 (10%) of the installations examined. [Fig-1]

Rust on screw connectors on circuit breakers, and less often on fuse terminals, was also common, occurring in 97 cases, slightly less than 10% of the systems examined. In some cases corrosion was so severe that not only was the connection questionable, but the connector screws themselves were so corroded that the electrician had to cut the wire when preparing to install new breakers. [Fig-2]

Corrosion at the connection of service entrance cable to main breakers or fuse connectors was found in 46 cases. It was common to see severe corrosion at this location when water was present. Evidence of overheating (burned insulation and discolored wire and in some instances partially melted aluminum wire) was observed at those connectors in several instances. Corrosion on neutral and grounding bus bars and connector screws was found in 42 cases. Evidence of overheating was seen in two of these cases. [Fig-3] , [Fig-4]

WHERE CORROSION OCCURS - in Electrical Panels?

Rust on steel service panel components is by far the most common observation, occurring in 110 (10%) of the installations examined. [Table 2]

Rust on screw connectors on circuit breakers, and less often on fuse terminals, was also common, occurring in 97 cases, slightly less than 10% of the systems examined. In some cases corrosion was so severe that not only was the connection questionable, but the connector screws themselves were so corroded that the electrician had to cut the wire when preparing to install new breakers. When severe rust is present we report that the operation of the circuit breakers might be suspect.

Corrosion on neutral and grounding bus bars and connector screws was found in 42 cases. However field data indicates that bus-bar connector corrosion so severe as to offer visual suggestion that the connection is highly questionable is rare. Evidence of overheating (possibly related to corrosion) was seen in only two of these cases, detected as discolored copper wires at the connector.

Corrosion at the connection of service entrance cable to main breakers or fuse connectors was found in 46 cases. However this connection gives cause for greater concern, as it is not uncommon to see severe corrosion at this location when water is present. We have observed evidence of overheating such as burned insulation and discolored wire and in some instances partially melted aluminum wire at such connectors.

MOISTURE SOURCES leaking or condensing in Electrical Panels

A significant advantage accrues from having a service panel inspected as part of a more comprehensive property inspection: home inspectors are concerned with the building envelope, with water entry, and with damage to building components from moisture.

In normally damp climates moisture is a major factor in building damage; identifying moisture sources and controlling moisture is important both in diagnosing failures and in protecting buildings from future failures. For each panel reported as a "problem" the inspector logged the apparent source of water entry. (For each of the 126 services for which defects were reported, the apparent sources of water entry was recorded.) [Table 3]

The most common sources of water and moisture entry were: through service entrance conductor cables which were old and damaged, or which were improperly sealed at meter boxes or building sidewalls; from condensation from high interior moisture levels; and from other building leaks or surface water which passed down building walls where panel enclosures were mounted.

ENTRY CABLE LEAKS - Service Entrance Cable (SEC) Leaks into Electric Panels

By far the most common source of water entry in service panels, 310 out of 472 possible sources observed, is associated with the passage of an above-ground service entry cable from outside, through the building wall, into panels which are located in basements or at a location lower than the point of penetration of the cable through the building wall.

There was often strong visual evidence that water had entered service enclosure, including: water stains and drip marks on components directly below the center of the entry cable when it enters the service equipment; water stains, sometimes rust marks, down the exposed face of circuit breakers; water droplets present on connectors and other components at the time of inspection.

Water, often in large volumes from wind-driven rain, followed the entrance cable into the building on three paths:

1. Frayed electrical service entry cable and bad seal at meter box top when the SEC is located above and enters the electric meter box top, when mounted outside (exposed to weather). [See [Fig-6].] Water entered the meter enclosure and traveled down the interior of the plastic-covered electrical service entrance cable into the building, often entering the service entry cable where that cable exited at the meter base. Notice the frayed SEC which also admits water into the cable itself as wind-blown rain strikes it.
2. Inadequately sealed electrical service entry cable connector: While frayed fabric-type SEC covering lets wind-blown rain enter the cable, meter box, and electrical panel, plastic-covered SEC wires form a virtual "water pipe into the electric panel," conducting water from the electric meter box into the electrical panel, as shown in , [Fig-5] This occurs when there is a leak into the electric meter box (frayed SEC cable or bad seal at top of the box where the cable enters), and where the electrical panel is mounted in the building at a level lower than that of the meter box.
3. Inadequately sealed opening where the cable passed through the building wall. A "drip loop" is not generally used at this location. Water followed the outside surface of the cable into the building panel. Capillary action may be a factor.[Fig-7]
4. Deteriorated, (worn, frayed fabric-covered) service entrance cables. Water entered the cable from wind-driven rain and followed a natural capillary path into the service panel.

WATER ENTRY PATHS - into Electric Panels from the SEC

Water, often in large volumes from wind-driven rain, follows the entrance cable into the building on three failure paths:

1. Failure to adequately seal the opening where the cable passes through the building wall. [A "drip loop" is never seen at this location, probably for aesthetic reasons.] Water follows the outside surface of the cable into the building panel. Capillary action may be a factor.
2. Failure to adequately seal the connector at the top of the electric meter, mounted outside. Water enters the meter enclosure and travels onward down the entrance cable into the building, often moving inside the service entry cable where that cable exits at the bottom of the meter base.
3. Failure to replace worn, frayed fabric-covered older service entrance cables. Water enters the cable from wind-driven rain and follows a natural capillary path into the service panel.

1. Water stains and drip marks atop panel components, usually the main breaker, directly below the center of the entry cable when it enters the panel from the top.
2. Water stains and drip marks on panel components and on panel base directly below the entry cable when it enters the panel from one side.
3. Water stains, sometimes rust marks, down the exposed face of circuit breakers
4. Visible droplets present on connectors and other components at the time of inspection.

OTHER BUILDING LEAKS - Affecting Electric Panels

A surprising number of occurrences of water entry appear to be due to other building leaks, 79 of 472. These sources include roof leaks (water passing from leaks into soffits through building walls and down basement wall - rare), and basement water entry associated with improper handling of roof runoff (leaky gutters) or surface drainage. Water concentrated around a building from roof runoff or surface drainage often results in moisture seeping through the foundation wall.

It's an interesting coincidence that service panels are often mounted in the corner of a basement, just where water may be concentrated outside from a faulty downspout. On a typical modern home with a single downspout at front and rear roof edges, chances are one in four that a service panel and a downspout will find themselves sharing a damp corner.

In such cases we've occasionally observed water entering the rear of the service panel at points of contact with the basement wall, even when the panel is actually affixed to plywood or nailer boards which themselves are fastened directly to the foundation. However the principal path from roof/surface runoff to panel is probably interior condensation due to high moisture levels caused by general basement water entry, discussed next.

The most common mechanism by which moisture entered these panels was from roof/surface runoff, causing basement water entry and high indoor moisture levels which in turn lead to condensation. This finding is discussed below. In a few other cases there were indications of water entering the rear of the service enclosure at points of contact with the basement wall, even when the enclosure was actually affixed to plywood or nailer boards which themselves were fastened directly to the foundation.

INDOOR CONDENSATION - Affecting Electric Panels

When water, corrosion, or signs of a history of wetness in service equipment were found and when there were no obvious contact-paths for droplets to travel in to the panel from outside, condensation inside the panel was recorded as the apparent source. In 83 of 472 cases there were wet-basement conditions but the service panel was mounted well away from points of outside water entry through walls or cables.

When moisture is observed primarily at specific panel locations, such as below the entrance cable or on the panel base, and when most other panel components are not corroded, we suspect specific points of outside entry such as described earlier.

But in many inspections we observe water, corrosion, or signs of a history of wetness in panels where there are no obvious contact-paths for droplets to travel in to the panel from outside.

In these cases, when corrosion is fairly uniform over panel enclosure sides and top, and over other panel components, we suspect that moisture is occurring as condensation inside the panel. Often the inspector will find such indications. This was so in 83 of 472 cases, when there were generally wet-basement conditions but when the service panel was fortunate to find itself mounted well away from points of outside water entry through walls or entry cables. While not a part of this study, we have observed this pattern of rust and corrosion on panel components even in very dry climates (Tucson and Phoenix) where electrical equipment was installed against masonry walls in service closets accessed from outside the building.

From these observations we suspect that the combination of high interior moisture levels in many basements, combined with temperature changes, results in movement of moisture to the interior of service panels on a regular basis during humid weather.

OTHER LEAKS - and Related Damage in Corroded Electrical Panels

1. during rainy weather, water visibly dripping into the panel through the entry cable See [Fig-5] ; white streaks down both black hot leads were deposited by water running inside the service entry cable.]
2. droplets clinging to interior panel breaker terminals and bus bars
3. standing water completely filling the panel base when a steel lip is installed thereon
4. moisture in small droplets, apparently condensation, soaking all panel components
5. circuit breaker terminals so completely rusted and corroded as to make removal of the terminal screw impossible [See previous Figures [Fig-1], [Fig-2], [Fig-3], [Fig-4]]
6. evidence of corrosion at aluminum entrance cables, regardless of use of anti-corrosive flux, sufficient to cause overheating of the cable and partial melting of its insulation
7. in an unheated basement subject to freezing, a Bakelite fuse pullout which had been damaged by moisture, cracked, and disintegrated when the inspector attempted to pull the main fuses, leaving one fuse in place, one fuse half-removed<196>an exciting moment for the inspector
8. burnout at connection between breaker, steel connecting screw, and aluminum bus-bar, resulting in loss of power in half the electric panel
9. unintended "connections" between sheet metal screws, very commonly used to replace lost machine-thread panel cover screws, and electric wires in the panel, in two cases resulting in a fire in the service panel.

PANEL AGE vs FAILURES - Electrical Equipment Age vs. Failure Rates in the Studied Population

The age of equipment varied from brand new to more than 50 years old. Most of these were circuit-breaker type panels (835), with the remainder fused equipment (217).

Service panel age did not necessarily match the age of the building. For many older homes historical and other evidence indicated that the service had been upgraded. For homes constructed before 1937, electric panels had often been upgraded two or more times.[Table 1]

No relationship was observed between type of equipment (fuse systems versus circuit breaker equipment) and the ability of water or moisture to enter the enclosures.

In this study, older equipment, subject to the same history of water entry, almost always looked less damaged from moisture. On such connectors and devices less extensive corrosion was found than on newer aluminum and steel screws, connectors, bus bars, and other components exposed to the same conditions.

Better data regarding actual failures might be surveyed among electricians performing replacements. Meese and Beausoleil have looked at failures in branch circuits.(3)

A common opinion among some experts was that fused equipment might be more reliable in damp/corrosive conditions than circuit breaker equipment. That view is based on the premise that electromechanical parts are more vulnerable than a fused link. However it's possible that the easier abuse of fuses (overfusing and bypassing) may offset the reliability advantage. (2)(3)(4) However other work by Keyes (1) and Popper (2) indicates that fusible panels may be more dangerous.This study did not test these opinions.

We did not tabulate the occurrence of corrosion, presence of defects, or evidence of failures, as a function of equipment age. However a subjective opinion is that older equipment, subject to the same history of water entry, almost always looks less damaged from moisture. We suspect that a factor is the use in older equipment of heavy copper and plated components. On such connectors and devices we see less extensive corrosion than on newer aluminum and steel screws, connectors, bus bars, and other components exposed to the same conditions.

Home inspectors rarely observe electrical equipment immediately after a catastrophe. It is common, however, for these specialists to find equipment in various states of deterioration of which the most severe might be just before a hard failure which would lead the homeowner to take corrective measures.

Occasionally the inspector will encounter new equipment in a property for sale and will observe the old devices abandoned (as trash) in the building. In these uncommon instances there may be opportunity to observe first hand the evidence of failure which led to equipment replacement. Better data regarding actual failures might be surveyed among electricians performing replacements. Meese and Beausoleil have looked at such failures in branch circuits.(5)

These views are confounded by the observation that in the geographic area studied service panel equipment is often 1960's vintage or newer. Older equipment has been replaced for several reasons: desire of owners to improve service ampacity, necessity to replace damaged or failed equipment, and requirements of lending institutions and recommendations from local power utility companies which cause services of less than 100 Amps to be replaced when houses are sold.

CORROSION-RELATED FAILURES - Evidence of Corrosion-Related Malfunction in Electrical Panels

Inspection practices exclude functional testing of electric panels.

Normal home inspection practice does not include performance of many tests on electrical equipment. It is common for inspectors to operate switches and controls which are provided for the homeowner (circuit breakers) or for use by service personnel (disconnects at HVAC equipment).

The Standards of Practice of the American Society of Home Inspectors require that every GFCI device be tested, that light switches and receptacles be sampled for proper operation and correct polarity and grounding. Inspectors may also verify that 240 volts is provided by the service. By contrast, testing for proper operation of a circuit breaker under load conditions requires special equipment, training, and procedures which are beyond the scope of a normal home inspection.(6)

Many inspectors are reluctant to operate circuit breakers, particularly main fuses or breakers, in occupied buildings. Often they will not do so without owner permission, because of risks of losses associated with unexpected power outage (e.g. computer was turned on upstairs, kidney dialysis machine was in operation). We have field reports of loss of building heat, with concomitant risks of freeze damage, when power was turned off as part of an inspection, only to discover that a faulty circuit breaker or main fuse could not be restored to power. Inspectors approach this topic with caution.(7)

As an incidental study, we tabulated frequency of certain very common "defects" observed in service panels, of which one, burned connectors, could possibly relate to the presence of corrosion. There were 23 such cases out of the 1052 panels observed, a 2% occurrence. In at least two of these 23 cases, the inspector noted evidence of an actual fire in the panel. (The number of panel defects will exceed the number of panels examined, since multiple defects may have been reported for individual installations.)

ANECDOTAL EVIDENCE - of Electrical Panel Malfunction from Corrosion

We did not tabulate severity of corrosion. Every case reported however was severe enough to merit having been reported to the building owner or buyer as a potential safety concern. As anecdotal evidence, we report having found:

• during rainy weather, water visibly dripping into the panel through the entry cable
• droplets clinging to interior panel breaker terminals and bus bars
• standing water completely filling the panel base when a steel lip is installed thereon
• moisture in small droplets, apparently condensation, soaking all panel components
• circuit breaker terminals so completely rusted and corroded as to make removal of the terminal screw impossible
• evidence of corrosion at aluminum entrance cables, regardless of use of anti-corrosive flux, sufficient to cause overheating of the cable and partial melting of its insulation
• in an unheated basement subject to freezing, a Bakelite fuse pullout which had been damaged by moisture, cracked, and disintegrated when the inspector attempted to pull the main fuses, leaving one fuse in place, one fuse half-removed<196>an exciting moment for the inspector
• steel screws connecting main breakers to aluminum bus-bars failed at the point of connection resulting in loss of power in half the electric panel
• sheet metal screws, very commonly used to replace lost machine-thread panel cover screws, have been found to pierce electric wires in the panel, in two cases resulting in a fire in the service panel.
• In 1991 the author participated in investigation of a fire (Pok NY Arnold Road) which was attributed to SEC cable fraying, leaks, corrosion, and a burnup at the electric panel in the building.

PANEL CORROSION CONCLUSIONS - Conclusions and Recommendations Regarding Electric Panel Leaks and Corrosion

Moisture from exterior leaks and interior condensation must be accepted as a very common hostile environment for service equipment in homes throughout a good part of the United States. Based on a large sample of electric service panels found in homes ranging from new to more than 100 years old in Southern New York, at least one of every ten units examined showed evidence of corrosion and moisture. One might expect worse conditions in more humid regions.

The most common sources of water and moisture entry appear to be: through service entrance conductor cables which are old and damaged, or which are improperly sealed at meter boxes or building sidewalls; from condensation from high interior moisture levels; and from other building leaks or surface water which pass down building walls where panel enclosures are mounted

Electric service components are not adequately protected from corrosion. In this study, corrosion was found at main entry cable connections, wire connectors on circuit breakers, wire connectors on neutral and grounding bus bars, and on the panel enclosure itself. Steel and aluminum components more often showed significant corrosion than do heavy solid copper components.

As a result of moisture and corrosion in service equipment, hazardous conditions may be expected. At some service cable connectors there was visual evidence to strongly suggest that corrosion had led to overheating and damage to the conductors. The observation of corroded circuit breaker and other panel connectors, and the presence of highly visible water marks and even water itself on circuit breakers raises serious questions: what is the corrosion resistance of internal parts? What conditions might be found on critical parts inside those devices?

Improvements in the design of electric service panel enclosures might include drainage and ventilation for service equipment enclosures and moisture-entry-resistant panel enclosure or panel backs and fastening methods. Similar improvements, possibly by minor design changes in the stamping of steel back and base plates of electric meter enclosures might be considered.

Leaks at and through contemporary service entry cables might be reduced by: reliable weather tight connectors at the top of exposed electric meters; use sealant to encapsulate the stripped cable end (inside the meter enclosure) whenever a service cable passes out the bottom of a meter enclosure to service equipment located below the meter; use improved sealant at the building wall opening made for passage of the cable to the building interior, or use of a weather tight bib designed for a variety of uneven and often flexible wall surfaces.

Steps to increase the corrosion resistance of entrance and breaker wire connections, bus bar connectors, screw terminals, might compensate for very common field conditions which continue to place this equipment at high risk of damage from moisture. St-Onge, addressing copper services, has made other suggestions for corrective measures, (11) and other studies have made more broad suggestions for design and installation improvements.(9) Improved materials are available and have been discussed in the literature by Breedis and Hauser.(10)

Effective corrosion resistance should be added to the present standards for qualification of electrical service equipment.

Perhaps it's not startling to note that we omit from these suggestions a greater emphasis on field training for installers. When electrical work is performed by a trained qualified electrician, it's generally obvious immediately when a device cover is removed. Unfortunately we are not the first observe a broad range of skill and training in electrical work, particularly in rural areas where building code enforcement may be lax and "improvements" are made by property owners and untrained mechanics. (9)

Combined with demanding field conditions which we've described in this article, improvements in component design may be a more successful step to reduce water entry, moisture, corrosion, and failures in electric service panel connectors and components.

MORE STUDY TOPICS - Additional Study of Electrical Panel Defects Is Needed

The author is continuing and expanding this study to allow examination of additional variables

1. Inspection field note forms have been modified to allow collection of pertinent details including manufacturer and model of service equipment.
2. A more aggressive attempt will be made to obtain failed and removed older equipment in order that it may be provided to professionals interested in testing for actual reliability of the devices which were removed as "suspect."
3. Effort will be made to extend the scope of collection of field data to other geographic regions: warm-dry regions of the Southwest where use of cooling equipment and a more casual attitude towards protection from weather are common; colder-more dry regions of northern regions.
4. Effort will be made to obtain survey results from a wider selection of professional inspectors, within guidelines to provide consistency of "opinion" regarding reportable defects.

Readers who have suggestions for critical observations which should be collected during field work are urged to contact the author, Dan Friedman - contact information is given at the end of this document.

BIBLIOGRAPHY - of Electric Panel/Wiring Inspection and Defects in Buildings

• Linda E. Smith, Dennis McCoskrie, "What causes wiring fires in residences?" Fire Journal, (Boston) Vol. 84 No. 1, Jan-Feb 1990 7p, ISSN 0015-2617. [Report of second phase of CPSC sponsored study, 149 fires investigated.]
• Wilhelm Popper, "Circuit Breakers or Safety Fuses in Residential Buildings, Considerations Associated With the Design of Electric Installations," Bulletin de L'Association Suisse des Electricians, Vol. 65 No. 13, June 29, 1974, p 957-963. [Selecting between fuses and circuit breakers.]
• R.L. Hicks, P. Liberatore, D. Bartlett, R. Major, "Reduction of fires caused by residential service entrance panel boards," Research Report, Canadian Electrical Association, No. 83-33, December 1983, 27p. [Ontario Hydro] [Field data identifies residential service panels as source of electrical fires. Not focused on corrosion-related failures.]
• W.J. Meese, Robert W. Beausoleil, "Exploratory Study of Glowing Electrical Connections," NBS Building Science Series, No. 103, October 1977 22p. ISSN 0083-1794.[Effects of loose electrical connections in residential branch circuits.]
• "Performance of Residential Electrical Wiring System Component Parts," Research Report, Canadian Electrical Association, No.000-U114, March 1982 112p, B.C. Research, Vancouver, BC, Canada. [Broad survey of residential electrical wiring component performance, addresses design, unpredicted usage, poor workmanship, not focused on corrosion.]
• "Standards of Practice," American Society of Home Inspectors, 1987-1991 (Rev.), 1735 N. Lynn St. Suite 950, Arlington, VA 22209-2022. [Includes minimum standards for visual inspection and reporting of the condition residential site, building, and mechanical systems during a home inspection.]
• D.J. Friedman, A. J. Carson, "Safety considerations for the electrical inspector," The ASHI Technical Journal, Vol. 2 No. 1, 1992, p. 9-14., ISSN 1061-7035. [Addresses safety limitations and concerns for home inspectors which in turn bound the field data collected from this source regarding connector failures and device corrosion.]
• D. Hansen, "Residential Electrical Inspection," Inspection Training Associates, Ver. 6.1, 38pp, October 1991, Los Altos, CA. [Detailed electrical inspection procedures for home inspectors.]
• C. Keyes, "Development of Design Guidelines and Practices for Improving Residential Service Entrances," Research Report, Canadian Electrical Association, 228-U-359, May 1987, various pagings, ISSN 0823-2660. [Identifies fusible panelboards as major source of electric fires.]
• J.F. Breedis, R. J. Hauser, "A new high strength copper alloy for electronic/electrical connectors," Eighteenth Annual Connectors and Interconnection Technology Symposium Proceedings, Philadelphia, PA, 1985. [Available from Olin Corporation, New Haven, CT]
• H. St-Onge, "Preventing Service Connection Corrosion," Water and Pollution Control, Vol. 124 No. 5, pp. 16-17, June 1986, Don Mills, Canada, ISSN 0043-1117.[Discusses copper services and corrective measures to avoid corrosion. Also addresses buried services not considered in this paper.]
• Acknowledgements: Invaluable assistance in editing this paper was provided by Dr. Laura W. Friedman and in editing technical content and organization by Dr. Jesse Aronstein.

LITERATURE SEARCH - Rust and Corrosion in Electrical Service Panels

Search Arguments and Databases scanned in 1990 looking for reports on rust and corrosion damage to electrical components and service panels:

In ENGI1 database
Set     Items   Description
S1       6327   ELECTRIC AND (SERVICE OR PANEL)
S2       1206   S1 AND (CORROS? OR RUST? OR BURN? OR BREAK? OR SHORT? OR D-EFECT? OR FIRE? OR BREAK?)
S3         54   S2 AND RESID?
S4         28   S3 AND RESIDENTIAL
S5        917   S2 NOT (ENERGY OR CONSERV? OR UTILIZ? OR COGENER? OR TRANSFORM?)
S6         91   S5 AND (CONNECT? OR WIRE)
S7         80   S6 NOT (POLLUT? OR SANIT? OR COMMERC?)
S8         71   S7 NOT MOTOR?
S9         71   S8 NOT CIVIL ENGINEERING
S10        71   S9 NOT CIVIL?
S11        65   S10 NOT (EARTHQU? OR TRANSMISSION)
S12        44   S11 NOT CONDUCT?
S13        26   S12 AND CONNECT?

S1       6327   ELECTRIC AND (SERVICE OR PANEL)
03036115   E.I. Monthly No: EIM9103-010031
  Title: Aging tests of amorphous current transformers used in ground fault
interrupters.
  Author: Nafalski, A.; Matras, G.; Wac-Wlodarczyk, A.; Stryczewska, H.
  Corporate Source: Lublin Tech Univ, Poland
  Conference Title: 1990 International Magnetics Conference - INTERMAG
  Conference Location: Brighton, Engl   Conference Date: 1990 Apr 17-20
  Sponsor: IEEE Magnetics Soc
  E.I. Conference No.: 14086
  Source: IEEE Transactions on Magnetics v 26 n 5 Sep 1990. p 2005-2007
  Publication Year: 1990
  CODEN: IEMGAQ   ISSN: 0018-9464
  Language: English
  Document Type: JA; (Journal Article)   Treatment: A; (Applications); X;
(Experimental)
  Journal Announcement: 9103
  Abstract: It is pointed out that the magnetic material for cores of a
differential current transformer (DCT) of a ground fault interrupter (GFI)
should be characterized by high initial permeability, little dependence on
temperature, and a low remanence. These parameters have been taken into
consideration during selection of the most suitable annealing regime of
Co-based (CoFeMnMo)//7//7(SiB)//2//3 material. It is assumed that a GFI is
required to have a service life of 20-years continuous operation. Hence,
the magnetic properties of the core of the DCT must be highly stable and
exhibit virtually no deterioration over this period. During its operational
lifetime, the core may be subjected to rapid saturation due to short
circuits and earth faults, etc., as well as cyclic temperature changes. The
effects of temperature aging and high current transients on the performance
of the DCT were investigated. It is concluded that current shocks do not
significantly alter the small-signal magnetic permeability of Co-based
amorphous cores of selected annealing. The material examined exhibits
degradation of magnetic properties due to aging greater than that reported
for Fe-based materials. The relatively rapid aging is probably connected
with the selected quick quenching in water following annealing. 9 Refs.
  Descriptors: *ELECTRIC INSTRUMENT TRANSFORMERS--*Aging; MAGNETIC
MATERIALS--Amorphous; ELECTRIC CIRCUIT BREAKERS; MAGNETIC CORES
  Identifiers: GROUND FAULT INTERRUPTERS; AMORPHOUS CURRENT TRANSFORMERS
  Classification Codes: 714  (Electronic Components); 421  (Materials
Properties); 708  (Electric & Magnetic Materials); 701  (Electricity &
Magnetism); 704  (Electric Components & Equipment)
  71  (ELECTRONICS & COMMUNICATIONS); 42  (MATERIALS PROPERTIES & TESTING);
70  (ELECTRICAL ENGINEERING)

02192698   E.I. Monthly No: EI8704034809
   Title:  METHODS  FOR  MITIGATING  CORROSION OF COPPER CONCENTRIC NEUTRAL
WIRES IN CONDUIT.
  Author: Anon
  Source: Electr Power Res Inst Rep EPRI EL 4981 Jan 1987 116P
  Publication Year: 1987
  CODEN: EPELD3
  Language: ENGLISH
  Document Type: RR; (Report Review)   Treatment: X; (Experimental)
  Journal Announcement: 8704
  Abstract: A method perfected in this study makes it possible to locate
and assess corrosion in underground distribution cables in conduit. In
addition, the study identified two techniques utilities can use to protect
such cables from corrosion, which has been an increasing problem in many
residential service areas. (Edited author abstract)
  Descriptors: *ELECTRIC POWER DISTRIBUTION--*Underground Installation;
ELECTRIC CABLES--Corrosion Protection; ELECTRIC CONDUITS; ELECTRIC
MEASUREMENTS--Resistance
  Identifiers: CORROSION EXTENT MEASUREMENT; UNDERGROUND RESIDENTIAL
DISTRIBUTION
  Classification Codes: 706  (Electric Transmission & Distribution); 539
(Metals Corrosion & Protection); 942  (Electrical & Electronic Measuring
Instruments)
  70  (ELECTRICAL ENGINEERING); 53  (METALLURGICAL ENGINEERING); 94
(INSTRUMENTS & MEASUREMENT)

02102866   E.I. Monthly No: EIM8607-045187
  Title: ECONOMICS OF DIRECT CONTROL OF RESIDENTIAL LOADS ON THE DESIGN AND
OPERATION  OF  THE  DISTRIBUTION  SYSTEM:  PART  III. THE ECONOMICS OF LOAD
MANAGEMENT.
  Author: Davis, Murray W.; Krupa, Theodore J.; Diedzic, Matthew J.
  Corporate Source: Detroit Edison Co, Detroit, MI, USA
  Conference Title: IEEE Power Engineering Society 1982 Summer Meeting.
  Conference  Location:  San Francisco, CA, USA   Conference Date: 1982 Jul
18-23
  Sponsor: IEEE Power Engineering Soc, New York, NY, USA
  E.I. Conference No.: 01344
  Source: Publ by IEEE, New York, NY, USA Pap 82 SM 441-4, 8p
  Publication Year: 1982
  Language: English
  Document Type: PA; (Conference Paper)
  Journal Announcement: 8607
  Abstract: This paper is the third in a series of three papers which
address the economics and effects of controlling central air conditioners,
electric water heaters, and service voltage on the design and operation of
the distribution system. The load characteristics measured throughout a
single distribution circuit over a five year period were used as a basis
for evaluating the benefits and costs of direct load control on the
distribution system. Models were developed to evaluate the impact of
various load control strategies on distribution system losses and on
changes in the thermal capacity of transformers and cables. A cost summary
is presented along with a break-even analysis which incorporates T&D system
benefits in an overall economic evaluation of load control. (Author
abstract) 4 refs.
  Descriptors: *ELECTRIC POWER DISTRIBUTION--*Economics; ELECTRIC POWER
SYSTEMS--Load Management; BUILDINGS--Air Conditioning
  Identifiers: DIRECT CONTROL; RESIDENTIAL LOADS; SINGLE DISTRIBUTION
CIRCUIT; THERMAL CAPACITY; LOAD CONTROL STRATEGIES; CENTRAL AIR
CONDITIONERS
  Classification Codes: 706  (Electric Transmission & Distribution); 911
(Industrial Economics); 402  (Buildings & Towers); 643  (Space Heating &
Air Conditioning)
  70  (ELECTRICAL ENGINEERING); 91  (ENGINEERING MANAGEMENT); 40  (CIVIL
ENGINEERING); 64  (HEAT & THERMODYNAMICS)

02820962   E.I. Monthly No: EIM8911-040960
  Title: Assessment of conductors.
  Author: Zollars, William B.
  Corporate Source: Alcoa Conductor Products Co, Pittsburgh, PA, USA
  Conference Title: Proceedings of the Sessions Related to Steel Structures
at Structures Congress '89
  Conference  Location:  San Francisco, CA, USA   Conference Date: 1989 May
1-5
  Sponsor: ASME, New York, NY, USA
  E.I. Conference No.: 12363
  Source:  Proc  Sess  Relat  Steel  Struct Congr. Publ by ASCE, New
York, NY, USA. p 74-82
  Publication Year: 1989
  ISBN: 0-87262-697-0
  Language: English
  Document Type: PA; (Conference Paper)   Treatment: X; (Experimental)
  Journal Announcement: 8911
  Abstract: This paper deals with the mechanical integrity of conductors
after several years in service and discusses current innovative conductor
designs which benefit the structural designer working to re conductor lines.
Conductor properties may be altered due to fatigue from aeolian vibration,
operation at elevated temperatures, and atmospheric corrosion. Loss of
strength and additional sag due to elevated temperature operation are also
discussed. (Edited author abstract) 2 Refs.
  Descriptors: *ELECTRIC CONDUCTORS, WIRE--*Testing; ELECTRIC LINES--Towers
  Identifiers: TRAPEZOIDAL STRANDS; ALUMINUM CONDUCTORS
  Classification Codes: 704  (Electric Components & Equipment); 421
(Materials Properties); 422  (Materials Testing)
  70  (ELECTRICAL ENGINEERING); 42  (MATERIALS PROPERTIES & TESTING)

02317438   E.I. Monthly No: EI8710103817
  Title: PREVENTING SERVICE CONNECTION CORROSION.
  Author: St-Onge, Hank
  Corporate Source: Duratron Systems Ltd
  Source:  Water  and  Pollution  Control (Don Mills, Canada) v 124 n 5 Jun
1986 p 16-17
  Publication Year: 1986
  CODEN: WPCOAR   ISSN: 0043-1117
  Language: ENGLISH
  Document Type: JA; (Journal Article)   Treatment: A; (Applications)
  Journal Announcement: 8710
  Abstract: Service connections and buried electrical systems joined to
non-metallic mains require special corrosion control measures. This article
discusses copper services and corrective measures that may be taken to
protect them. Also discussed are buried electrical systems, corrective
measures, sacrificial anode applications, and anode requirements.
  Descriptors: *PIPELINES--*Corrosion Protection; ELECTRIC LINES--Corrosion
Protection; CORROSION PROTECTION, ANODIC
  Identifiers: SERVICE CONNECTION
  Classification Codes: 619  (Pipes, Tanks & Accessories); 539  (Metals
Corrosion & Protection); 706  (Electric Transmission & Distribution)
  61  (PLANT & POWER ENGINEERING); 53  (METALLURGICAL ENGINEERING); 70
(ELECTRICAL ENGINEERING)

02278688   E.I. Monthly No: EIM8710-067724
   Title: C724 - A NEW HIGH STRENGTH COPPER ALLOY FOR ELECTRONIC/ELECTRICAL
CONNECTORS.
  Author: Breedis, J. F.; Hauser, R. J.
  Corporate Source: Olin Corp, New Haven, CT, USA
  Conference   Title:  Eighteenth  Annual  Connectors  and  Interconnection
Technology Symposium Proceedings.
  Conference  Location:  Philadelphia,  PA, USA   Conference Date: 1985 Nov
18-20
  Sponsor: Electronic Connector Study Group Inc, Fort Washington, PA, USA
  E.I. Conference No.: 09575
  Source:   Annual  Connectors  and  Interconnection  Technology  Symposium
Proceedings  18th.  Publ  by  Electronic  Connector  Study  Group Inc, Fort
Washington, PA, USA p 123-130
  Publication Year: 1985
  CODEN: ACIPE3
  Language: English
  Document Type: PA; (Conference Paper)
  Journal Announcement: 8710
  Abstract: A new high strength, precipitation hardened copper alloy has
been developed for the electronic/electrical connector market in response
to the need for high reliability and stability in service, while minimizing
material cost. The alloy, designated as C724, has a Cu-Ni-Al base
composition with supplemental additions of Mg and Mn. Physical and
mechanical properties of this alloy that are important to designers of
electronic/electrical connectors are summarized, as well as compared with
other copper alloys used in this application. C724 is available in two mill
hardened tempers encompassing yield strengths of between 100 to 140 KSI
with isotropic longitudinal and transverse minimum bend radius limits of 1.
5-3t. The alloy is resistant to stress relaxation with at least 90% of the
initially imposed stress expected to remain after 10 years at 221 DEGREE F
(105 DEGREE C). The alloy also has excellent stress corrosion resistance,
comparable to mill hardened beryllium copper alloys. (Edited author
abstract) 4 refs.
  Descriptors: *ELECTRIC CONNECTORS--*Materials; COPPER AND ALLOYS--
Applications
  Identifiers: HIGH STRENGTH COPPER ALLOY; ELECTRONIC/ELECTRICAL CONNECTORS
; CONNECTOR MATERIALS DESIGN; STRESS RELAXATION; STRENGTH RELAXATION;
ISOTROPIC BEND PROPERTIES
  Classification Codes: 704  (Electric Components & Equipment); 544
(Copper & Alloys); 714  (Electronic Components)
  70  (ELECTRICAL ENGINEERING); 54  (METAL GROUPS); 71  (ELECTRONICS &
COMMUNICATIONS)

01890891   E.I. Monthly No: EIM8509-052110
  Title: INFRARED INSPECTION OF UNDERGROUND SECONDARY CONNECTIONS.
  Author: Gitto, Joseph F.; Perl, Martin
  Corporate  Source:  Consolidated Edison Co of New York Inc, New York, NY,
USA
  Conference Title: Proceedings of the 9th Annual Engineering Conference on
Reliability for the Electric Power Industry.
  Conference Location: Hershey, PA, USA   Conference Date: 1982 Jun 16-18
  Sponsor:  IEEE  Reliability  Soc,  New York, NY, USA; AIIE, Lehigh Valley
Chapter,  USA;  EPRI,  Palo  Alto,  CA, USA; ASQC, Milwaukee, WI, USA; ANS,
Delaware Valley Section, USA; et al
  E.I. Conference No.: 05668
  Source: Publ by ASQC, Milwaukee, WI, USA p 294-296
  Publication Year: 1982
  Language: English
  Document Type: PA; (Conference Paper)
  Journal Announcement: 8509
  Abstract: The application of infrared (IR) scanning by utilities for
aerial surveys of residences, inspection of substation equipment and
overhead connections is well known. This paper describes a new application
for IR scanning - inspection of underground secondary connections in
manholes and secondary service boxes. Infrared scanning of underground
secondary connections, at Con Edison, has been found to be a viable method
for preventive maintenance. Detection of potential failures permits an
orderly and timely repair of the defective condition before the existence
of an emergency (customer outage) condition.
  Descriptors: *THERMOGRAPHY--*Applications; ELECTRIC CONNECTORS--
Nondestructive Examination; FAILURE ANALYSIS
  Identifiers: INFRARED INSPECTION; SCANNING; UNDERGROUND SECONDARY
CONNECTIONS
  Classification Codes: 944  (Moisture, Pressure & Temperature, & Radiation
Measuring Instruments); 704  (Electric Components & Equipment); 714
(Electronic Components); 421  (Materials Properties); 422  (Materials
Testing)
  94  (INSTRUMENTS & MEASUREMENT); 70  (ELECTRICAL ENGINEERING); 71
(ELECTRONICS & COMMUNICATIONS); 42  (MATERIALS PROPERTIES & TESTING)

       30mar91 15:21:50 User042798 Session B20.4
     $9.67    0.406 Hrs FileKI
     $9.67  Estimated total session cost   0.406 Hrs.
Logoff: level 25.02.16 B  15:21:50

(second access, same date) In ENGI1 database
Set     Items   Description
S1          0   RESIDENTIAL SERVICE PANEL
S2       1401   ELECTRIC? AND (RESIDENTIAL)
S3         23   S2 AND PANEL?
S4         22   S3 NOT PANEL MEASUREM?
S5         21   S4 NOT COGENER?
S6         19   S5 NOT LOAD MANAGEMENT
S7         16   S6 NOT POWER GENERATION
S8         16   S7 NOT CONSERVAT?
S9         16   S8 NOT VIDON
S10        15   S9 NOT UNDERGROUND
S11        11   S10 NOT PHOTOVOLTAIC
S12        11   S11 NOT OPTICAL

 11/L/7
01476082   E.I. Monthly No: EI8401002616   E.I. Yearly No: EI84040628
   Title:  PERFORMANCE  OF  RESIDENTIAL  ELECTRICAL WIRING SYSTEM COMPONENT
PARTS.
  Author: Anon
  Corporate Source: B. C. Research, Vancouver, BC, Can
  Source: Res Rep Can Electr Assoc n 000 U 114 Mar 1982 112p
  Publication Year: 1982
  CODEN: RCEADM
  Language: ENGLISH
  Journal Announcement: 8401
  Abstract: The general performance of many residential electrical wiring
system components is examined, and some components, like receptacles,
extension cords, incandescent light fixtures, fluorescent light ballasts,
panelboards, and nylon-sheathed wire, are found unacceptable because of
poor quality control, poor design, unpredicted current 'normal' use
conditions, lack of compatible accessories, poor installation workmanship,
manufacturing economics, and other factors. A case is made for the
imposition of improved performance standards for some residential
electrical wiring components on the grounds of reducing annoyance,
apprehension, and the incidence of serious consequences of component
failures. Better means for inspection authorities are suggested to gather
and collate information on performance for prompt forwarding to the
standards committees empowered to enact and improve performance standards.
Refs.
  Descriptors: *ELECTRIC WIRING, BUILDINGS--*Components; ELECTRIC WIRING--
Performance
  Identifiers: RESIDENTIAL WIRING COMPONENTS PERFORMANCE
  Classification Codes: 402  (Buildings & Towers); 706  (Electric
Transmission & Distribution)
  40  (CIVIL ENGINEERING); 70  (ELECTRICAL ENGINEERING)

?f residential service entrance and (electric? or panel)
            5622  RESIDENTIAL
           47149  SERVICE
            3715  ENTRANCE
               4  RESIDENTIAL SERVICE ENTRANCE
          315005  ELECTRIC?
            9233  PANEL
     S14       4  RESIDENTIAL SERVICE ENTRANCE AND (ELECTRIC? OR PANEL)
 14/L/1
02530600   E.I. Monthly No: EI8803023150
   Title:  DEVELOPMENT  OF  DESIGN  GUIDELINES  AND PRACTICES FOR IMPROVING
RESIDENTIAL SERVICE ENTRANCES.
  Author: Keyes, C.
  Corporate Source: Ontario Research Foundation, Toronto, Ont, Can
  Source: Res Rep Can Electr Assoc 228 U 359 May 1987 var pagings
  Publication Year: 1987
  CODEN: RCEADM   ISSN: 0823-2660
  Language: ENGLISH
  Document Type: RR; (Report Review)   Treatment: T; (Theoretical); X;
(Experimental)
  Journal Announcement: 8803
  Abstract: Residential service entrance fusible panelboards are a major
identifiable cause of electric fires. Although some remedial measures have
been taken, a continuing change to more cyclic loading on panelboards in
the form of electric heating may cause a resurgence of failures in the
future. The primary objectives of this three-part report were to
investigate the problems associated with new and existing service entrance
equipment and to establish design guidelines and practices for improved
reliability particularly where loads such as electric heat are involved.
Parts I and II explore in detail the reliability issues surrounding
existing and new service equipment respectively. Based on the conclusions
and recommendations of these two parts, the guidelines for improving
service entrance equipment reliability, found in Part III, are developed.
38 refs.
  Descriptors: *ELECTRIC SWITCHBOARDS--*Reliability; ELECTRIC LOADS;
ELECTRIC CIRCUIT BREAKERS; ELECTRIC SWITCHES--Testing; STANDARDS; ELECTRIC
CONTACTS--Failure
  Identifiers: RESIDENTIAL SERVICE ENTRANCE RELIABILITY TESTING; INSULATION
TESTS; ELECTRICAL TESTS; WEIBULL STATISTICS; ARRHEMIUS MODEL
  Classification Codes: 704  (Electric Components & Equipment); 706
(Electric Transmission & Distribution); 922  (Statistical Methods); 902
(Engineering Graphics & Standards)
  70  (ELECTRICAL ENGINEERING); 92  (ENGINEERING MATHEMATICS); 90  (GENERAL
ENGINEERING)

 14/L/2
02294586   E.I. Monthly No: EI8708079092
  Title: RESIDENTIAL SERVICE ENTRANCE CURRENT UNBALANCE.
  Author: Anon
  Corporate Source: Ontario Hydro, Toronto, Ont, Can
  Source: Res Rep Can Electr Assoc 234 U 384 Apr 1985 80p
  Publication Year: 1985
  CODEN: RCEADM   ISSN: 0823-2660
  Language: ENGLISH
  Document Type: RR; (Report Review)   Treatment: A; (Applications); X;
(Experimental)
  Journal Announcement: 8708
  Abstract: The residential service entrance current unbalance study is a
preliminary survey of line-to-line current unbalances at the service
entrance of typical homes during the heating season. This information is of
interest to heating equipment and control manufacturers and the electrical
utilities involved in the off-oil program. The results provide an
indication of the improvements possible from electrical load redistribution
and whether the electrical distribution panelboard and plenum heaters are
being utilized to the full potential. 2 refs.
  Descriptors: *ELECTRIC POWER SYSTEMS--*Load Distribution; HEATING--
Electric; ELECTRIC POWER DISTRIBUTION; ELECTRIC APPLIANCES
  Identifiers: LOAD DISTRIBUTING CONTROLLER; SPACE HEATING SYSTEMS; CURRENT
UNBALANCES; HOMEOWNERS' ELECTRICAL SYSTEM
  Classification Codes: 706  (Electric Transmission & Distribution); 643
(Space Heating & Air Conditioning); 704  (Electric Components & Equipment)
  70  (ELECTRICAL ENGINEERING); 64  (HEAT & THERMODYNAMICS)

?f circuit breaker?
           83508  CIRCUIT
            4587  BREAKER?
     S15    3517  CIRCUIT BREAKER?
?f s15 and residential
            3517  S15
            5622  RESIDENTIAL
     S16      10  S15 AND RESIDENTIAL
?type s16/l/all

00404433   E.I. Monthly No: EI7410060568
   Title:  Circuit  Breakers  or  Safety  Fuses  in  Residential Buildings.
Considerations Associated with the Design of Electric Installations.
  Title:    LEITUNGSSCHUTZSCHALTER   ODER   SICHERUNGEN   IM   WOHNUNGSBAU.
UEBERLEGUNGEN BEI DER PLANUNG ELEKTRISCHER INSTALLATIONEN.
  Author: Popper, Wilhelm
  Corporate Source: Bernische Kraftwerke, Bern, Switz
  Source:  Bulletin  de l'Association Suisse des Electriciens v 65 n 13 Jun
29 1974 p 957-963
  Publication Year: 1974
  CODEN: BUSEAH   ISSN: 0004-587X
  Language: GERMAN
  Journal Announcement: 7410
  Abstract: Criteria for the selection between circuit breakers and fuses
are indicated. The importance of maximum short-circuit current is pointed
out and a simple method for its determination is presented, along with two
practical examples. The effect of local conditions on the decision between
circuit breakers and fuses is discussed. Problems associated with series
connection of circuit breakers are considered. 2 refs. In German.
  Descriptors: *BUILDINGS--*Electric Equipment; ELECTRIC CIRCUIT BREAKERS;
ELECTRIC FUSES
  Classification Codes: 402  (Buildings & Towers); 704
(Electric Components & Equipment); 914  (Safety Engineering)
  40  (CIVIL ENGINEERING); 70  (ELECTRICAL ENGINEERING);
91  (ENGINEERING MANAGEMENT)

 21/L/1
02523070   E.I. Monthly No: EIM8801-003024
   Title:  EFFECT  OF  HARD  WATER  SCALE  BUILDUP  AND
WA