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How to Inspect Residential Electrical Systems, Panels, Grounding, Wiring - Part 2
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• Electrical inspection vocabulary
• Electrical inspection of the service drop and service wire clearances
• Online Course on how to inspect electrical panels

This document discusses procedures for safe and effective visual inspection of residential electrical systems including electrical panels and other components, when the inspection is conducted by trained building inspection professionals, home inspectors, electrical inspectors, and electricians. It was presented by Daniel Friedman - InspectApedia.com, at the Hudson Valley chapter of the American Society of Home Inspectors - HVASHI Seminar 12 Sept 2002, Updated April 2006, April 2009.

Readers of this article should also be sure to review Safety Hazards and Safe Electrical Inspection Procedures for Inspectors examining Residential Electrical Systems and should pay special attention to the following chapters from that article:   Electrical Panel Interior Inspection -  Removing Electric Panel Covers -  Electrical Panel Cover Screws -  Electrical Panel Interior Hazards -  Testing Main Breakers or Fuses and  Inspect Breakers, Fuses. Carson Dunlop's sketch at page top shows where the electrical inspection starts at a residential property.

© 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.

Electrical Vocabulary for Residential Electrical Inspectors

Readers of this article should see our detailed definitions at DEFINITIONS of ELECTRICAL TERMS and AMPS & VOLTS DETERMINATION and at Electrical Circuits, shorts.

• Service Drop/Service Laterals (overhead/underground from street) - Inspection not required; [note clearance/tree/condition/number of wires]
• Service Entrance (masthead, service entrance conductors, meter/meter)
• Service Voltage
• Service Amperage
• Service Equipment
• Service disconnect - main overcurrent dev.
• Service box, main panel, service panel
• Grounding equipment - rod/electrode, grounding conductor
• Grounding wire: the "ground wire," normally inactive, alternative path from various devices to ground, exercised in abnormal conditions to permit fuse to blow and reduce shock hazard
• Grounded wire: neutral wire, normally carries return current, in daily use, gives flow path of current from source to earth
• Grounding electrode conductor: "the ground wire" from service equipment to ground at water pipe or electrode(s)
• Equipment grounding conductors: "ground wires" on each branch circuit throughout the house
• Grounding: connect something to earth (0 potential)
• Bonding: joining two electrical conductors so will be at same electrical potential (FYI: gas piping not used for grounding, is bonded to the grounding system)
• Arc fault circuit interrupters: see AFCIs ARC FAULT CIRCUIT INTERRUPTERS

Inspecting the Electrical Service Drop or Service Lateral bringing electrical power to a building

Electrical Service Drop Wire Clearances and Other Defects

• roadway 18 ft. overhead
• driveway 12 ft. overhead
• flat roof 8-10 ft. overhead
• roof 18" at mast, 3 ft. passing over
• walkway 10 ft. overhead
• swim pool 18 ft. vertical clearance, 10 ft. horizontal clearance
• not over 30 ft. above grade
• less than 3 ft. from windows, fire escapes, doors
• damaged, frayed
• trees, vines
• well-secured to house
• well-connected to service entrance cable (SEC)

Sketches above are courtesy of Carson Dunlop.

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• * Safety Hazards and Safe Inspection Procedures for Electrical and Home Inspectors at Residential Electric Panels
• Additional technical contributors & reference sources for this article are listed below.

Use links just below or 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.

ELECRICAL PANEL INSPECTION
COURSE SUMMARY
ELECTRICAL INSPECTION SAFETY
ELECTRICAL VOCABULARY
SERVICE DROP
  WIRE CLEARANCES
SERVICE ENTRY WIRING
DETERMINE SERVICE AMPACITY
  TABLE OF SERVICE AMPACITY
  SERVICE AMPACITY DEFECTS
ELECTRICAL GROUND SYSTEM INSPECTION
  TABLE OF GROUND WIRE SIZES
  SERVICE GROUNDING
MAIN DISCONNECT
  MAIN SWITCH LOCATION
  MAIN SWITCH
SYSTEM GROUNDING
DISTRIBUTION PANELS
  PANEL COVER
  CIRCUIT WIRING AMPS FUSING
  PROBLEM-BRAND ELEC PANELS
  ELEC PANEL LOCATION
  FUSES vs CIRCUIT BREAKERS
  MAIN DISCONNECT INSPECTION
  OTHER PANEL DEFECTS
ELECTRICAL BASICS

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
• ...

More Information on Building Diagnostic Inspections and Repairs

• Aluminum Wiring Information Website Aluminum Electrical Wiring Hazards and Repairs: in-depth authoritative info, photos, documents including selection of proper vs. ineffective repair methods. E.g.: Ideal 65 "Twister" purple connector fails in field and lab testing with aluminum wire.
• Ampacity of an Electrical Service: How to determine the electrical service size or ampacity entering a building
• Circuit Breaker, a bad one fails to trip failure at aluminum bus-to-circuit breaker connection - field report and photographs
• Electrical Panels, How to Inspect in Buildings, safety for electrical inspectors, electrical panel, fusing, wiring defects, defective products. Inspection Class Presentation
• Federal Pacific Electric (FPE) Stab-Lok Circuit Breaker Panel Hazards Website - Latent fire hazards, in-depth authoritative research, documents, advice on Stab-Lok electric panel and circuit breaker failures and what to do when this equipment is found in buildings.
• Lightning Strike Risk Assessment, Protection Systems & Services
• Multi-wire branch circuit inspection and defects
• Zinsco Electrical Circuit Breaker Failures: overheating, failure to trip, burn-ups involving Zinsco and certain Sylvania electrical panel components - page under development March 2006.
• "Electrical System Inspection Basics," Richard C. Wolcott, ASHI 8th Annual Education Conference, Boston 1985.
• "Simplified Electrical Wiring," Sears, Roebuck and Co., 15705 (F5428) Rev. 4-77 1977 [Lots of sketches of older-type service panels.]
• "How to plan and install electric wiring for homes, farms, garages, shops," Montgomery Ward Co., 83-850.
• "Electrical System Inspection Basics," Richard C. Wolcott, ASHI 8th Annual Education Conference, Boston 1985.
• "Simplified Electrical Wiring," Sears, Roebuck and Co., 15705 (F5428) Rev. 4-77 1977 [Lots of sketches of older-type service panels.]
• "How to plan and install electric wiring for homes, farms, garages, shops," Montgomery Ward Co., 83-850.
• "Home Wiring Inspection," Roswell W. Ard, Rodale's New Shelter, July/August, 1985 p. 35-40.
• "Evaluating Wiring in Older Minnesota Homes," Agricultural Extension Service, University of Minnesota, St. Paul, Minnesota 55108.
• "Electrical Systems," A Training Manual for Home Inspectors, Alfred L. Alk, American Society of Home Inspectors (ASHI), 1987, available from ASHI. [DF NOTE: I do NOT recommend this obsolete publication, though it was cited in the original Journal article as it contains unsafe inaccuracies]
• "Basic Housing Inspection," US DHEW, S352.75 U48, p.144, out of print, but is available in most state libraries.
• Rust and Corrosion in Electrical Panels, A Study and Report on Frequency and Cause for Electrical and Home Inspectors at Residential Electric Panels


• Directory of Home Inspectors accessible via internet
• Electrical System & Wiring Hazard Inspection, Detection, Cause, Remedy, Prevention - Main Electrical Page

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