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Table of Underground Electrical Service Cable Sizes & Amps InspectAPedia®  -

• Table of underground electrical service cable sizes & amps assists inspectors in determining the capacity of electrical service at buildings
• How to determine the size, capacity, or ampacity of electrical service at a building

This article 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, and other details. Visual inspection and use of digital multimeters(DMMs), Volt-ohm meters (VOMs), neon testers, and electrical inspection safety are discussed. © Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

UNDERGROUND Electrical SERVICE LATERALS - delivering current to a building

Electrical Services provided through underground conduit do not permit visual inspection of the service conductor prior to the electric meter and actual conductors are visible only in the service panel.

It is possible to guess at the cable run in a conduit by the diameter of the conduit itself [Table 2.] But for conductors from the utility company's drop to the meter, conduit size sets only the maximum conductor that could be contained, not necessarily the actual size.

Notes to Table:
Pipe sizes are nominal; for copper wires.

Do not attempt to open the meter base. If you are unable to determine the wire ampacity because there is no view, or because its dimension is not one with which you are familiar, say so.

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• The Original Authors: Alan Carson is an ASHI Member, national home inspection educator, author and building failures researcher in Toronto, Ontario. Daniel Friedman, an original author of this article and the editor and producer of InspectAPedia where this article now appears is an ASHI Member, first ASHI Technical Committee chairman, editor and publisher of the ASHI Technical Journal, licensed home inspector, educator, and building failures researcher in Poughkeepsie, NY. Robert Klewitz is a licensed professional engineer, a professional home inspector, an ASHI Member, and has served on the ASHI Technical Committee as well as in other ASHI activities. His practice is in Issaquah, WA.
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• Douglas Hansen, Robert Stead. Mark Cramer. Photographs: Daniel Friedman.
• Critique, contributions wanted: Contact Us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.
• N. Srinivasan, MSEE, is a senior member of IEEE with 30 years experience in the electrical industry. Mr. Srinivasan is in Vienna VA.
• Louis P. Babin generously contributed technical editing about the effects of doubling ampacity in an electrical circuit (September 2007)

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