Electric meter inspection & repair:

This article discusses the visual inspection of electrical meters & meter bases & explains how to estimate the electrical service size, (or "electrical power" or "service amps") at a building by visual examination of the service entry cables, electric meter and meter base, electrical service panel, main switch, & other details.

We describe types of electric meters, meter inspection points, and how to read an electric meter. We also discuss electrical arc burns at the meter base and we include case reports of electric meter base overheat and arcing damage, failures, and repairs.

Beware of Overheating, Arcing, Corrosion at Electric Meter Mounting Bases

Experienced Electrical Worker Warns of Electric Meter Base Arcing & Burns

Our photos show a simple electrical meter base and meter connection mounts where arcing was not present. Field photos of electric meter damage or arcing are wanted. CONTACT us.

There's one important point about electrical meter sockets I'd like to make. I've been in the electrical trade since 1976, and have seen a lot of interesting situations over the years. One that I feel needs to be addressed is on existing installations, involving arcing at the meter stabs.

I live in California, and So. Cal. Edison loves their "vandal proof" meter locking rings, so in order to do a "proper" service entrance inspection, we have to call a service tech out to unlock the meter ring, they always pitch a "bad time", about coming all the way out to unlock a ring, but it's my reputation and the customer's safety that are both on the line.

More than once, but not really-often I've discovered electrical arcing damage to the electrical meter mounting stabs. Arcing and burning in this location can only be seen by removing the meter.

When I find one of these electrical meter mount arc-burn cases, the Edison guy is always amazed.

Not too many sparky's pull the electrical meters to inspect the meter connections, but I recommend it.

And pulling all the breakers off the bus and checking for discoloration or arcing on the bus bars, and breaker clips is a good practice to live by, Especially Zinsco panels

and especially 30 and 40 amp breakers.

See ZINSCO / SYLVANIA HAZARDS

and

GTE-SYLVANIA-ZINSCO FAILURE MECHANISM

- Kirk Schwoebel

Photographs of Arcing Damage & Heat Damage at Connectors in Electric Meter Bases

The electrical meter arcing damage photographs below were provided courtesy of Robert McBride.

Above, the photograph of an electrical meter base shows severe arcing burns at the connecting jaws.

Below in the second photo you will note (arrow) arc burns at the upper left connector in the photograph.

The contributor indicated that this arcing burn occurred because the meter was inserted into the meter base while the system was under load.

Below the McBride photo of a burned electrical meter base connection shows heat damage at the electric meter mounting base due to loose connections.

Keep in mind that even minor electrical arcing such as shown in the photograph at right can be the beginning of a more serious problem, failure, or electrical fire.

That's because electrical resistance created by the flashover burned materials at the connection increases heating and future arcing or burn risks at that same connector.

The articles from which some of this online material originated appeared first in the ASHI Technical Journal, Vol. 2. No. 1, January 1992, "Determining Service Ampacity," Dan Friedman and Alan Carson, and the ASHI Technical Journal, Vol. 3. No. 1, Spring, 1993, "Determining Service Ampacity - Another Consideration," Robert L. Klewitz, P.E.,

with subsequent updates and additions to the original text ongoing to 2/19/2006.

Reprints of the originals and reprints of the Journal are available from ASHI, the American Society of Home Inspectors www.ashi.com

Readers of this article should also be sure to

review SAFETY HAZARDS & SAFE ELECTRICAL INSPECTION PROCEDURES for examining Residential Electrical Panels.

Aluminum-to-Copper SEC Connection Leads to Electric Meter Burn-Up Failure

In a case similar to the U.S. electric meter burn damage reported above by a California reader,

at ELECTRIC METER OVERHEAT AL to CU WIRING we illustrate a wiring connection overheat that resulted in melting electric meter parts and loss of electrical power in one side of the electrical panel of a home in central Mexico.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2022-09-03 by InspectApedia-911 (mod) - Zinsco panel replaced after electric meter overheat, SEC short, electrical damage

@Richard Bressler,

Thank you for posting this important Zinsco electric meter base failure report.

Indeed we visited the site of a house fire caused by a similar failure in the meter base: overheating at a connector melts insulation, shorts wiring, and can actually set the building on fire.

It's good news that your failure was found soon-enough to avoid such a loss.

I add, however, that we've seen this failure at other electric meter bases that have nothing to do with Zinsco per-se.

It appears that a common cause of these failures is a poor electrical connection of aluminum wiring inside the meter base, leading to micro-fretting, arcing, then overheating at the connection.

The underlying cause is often the failure to properly abrade the aluminum wire and use an antioxidant on the connections.

When we had the same failure at an electric meter we asked the electricians to be sure to abrade the aluminum wire under antioxidant, then add more antioxidant when connecting the wire to the terminals in the meter base.

See details at [above on this page] and a similar example

at ELECTRIC METER OVERHEAT AL to CU WIRING

On 2022-09-03 by Richard Bressler - We kept hearing the arcing sound. I lifted the cover and the cabinet was very warm.

Had our Zinsco panel replaced yesterday. Ours had a little different problem, but a failure it was. The upper right meter jaw overheated and distorted, not making good contact the insulation on that supply cable melted off up till it reached the riser conduit.

[Photo above]

Once it made contact with metal it arced so much it actually severed the cable but continued arcing. The symptoms were: some lights and outlets going in and out randomly but not tripping breakers. the oven clock kept losing its time.

We kept hearing the arcing sound. I lifted the cover and the cabinet was very warm. Other than seeing the occasional arcing because it was dark out the panel looked normal. All the trouble was hidden behind the meter.

2nd photo entrance cables short to conduit

This reader commennt and our reply were posted originally

at GTE-SYLVANIA-ZINSCO FAILURE MECHANISM

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Continue reading  at ELECTRIC METER OVERHEAT AL to CU WIRING or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• ELECTRIC METERS & METER BASES
• ELECTRIC METER BASE vs SERVICE AMPS
• ELECTRIC METER RATING vs SERVICE AMPS
• HOW TO INSPECT ELECTRIC METERS & BASES
• ELECTRIC METER CLEARANCE DISTANCES & WORKING SPACE
• ELECTRIC METER ARC BURN POWER LOSS
• ELECTRIC METER OVERHEAT AL to CU WIRING
• ELECTRIC METER RUNS BACKWARDS
• SMART or DIGITAL ELECTRIC METER READINGS
• ELECTRIC POWER LOSS / FLICKERING LIGHTS
• MAIN ELECTRICAL DISCONNECT

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INDEX to RELATED ARTICLES: ARTICLE INDEX to ELECTRICAL INSPECTION & TESTING

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