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ELECTRICAL INSPECTION, DIAGNOSIS, REPAIR

AFCIs ARC FAULT CIRCUIT INTERRUPTERS
ALUMINUM SECs & WIRING
ALUMINUM WIRING HAZARDS & REPAIRS
AMPS & VOLTS DETERMINATION
AMPACITY - the LIMITING FACTOR
APPLIANCE EFFICIENCY RATINGS

BACKUP ELECTRICAL GENERATORS
BOOKSTORE - ELECTRICAL
BUILDING SAFETY HAZARDS GUIDE

Cadet & Encore Heater Recall
CIRCUIT BREAKER FAILURE
Classified CIRCUIT BREAKER WARNING
CIRCUIT BREAKER SIZE for A/C or HEAT PUMP
Classified CIRCUIT BREAKER WARNING
CUTLER HAMMER PANEL FIRE
CONDUIT, ELECTRICAL
CORROSION in ELECTRICAL PANELS
CORROSION & MOISTURE SOURCES in PANELS

DEFINITIONS of ELECTRICAL TERMS

DIRECTORY OF ELECTRICIANS

ELECTRIC HEAT
ELECTRIC METERS & METER BASES
ELECTRIC MOTOR DIAGNOSTIC GUIDE
ELECTRIC MOTOR OVERLOAD RESET SWITCH
ELECTRIC PANEL AMPACITY
ELECRICAL PANEL INSPECTION
ELECTRICAL INSPECTION SAFETY
ELECTRICAL VOCABULARY
ELECTRICAL SERVICE DROP
  WIRE CLEARANCES
ELECTRICAL SERVICE ENTRY WIRING
    DETERMINE SERVICE AMPACITY
  TABLE OF SERVICE AMPACITY
  SERVICE AMPACITY DEFECTS
ELECTRICAL GROUND SYSTEM INSPECTION
  Electrical Grounding Basics
  Gas Piping Ground Bond
  TABLE OF GROUND WIRE SIZES
  Old House Electrical Grounding
  False Ground at Receptacles
  False Neutral Connections
  Case History: Double Fault Leads to Loss of Power
  Case History:Loss of Neutral Shocks Homeowner
  Electrical Service Grounding Checklist
  Why Grounding is Needed
  ELECTRICAL SYSTEM GROUNDING
  SERVICE GROUNDING DEFECTS
  TABLE OF GROUND WIRE SIZES
  Old House Electrical Grounding
ELECTRICAL SYSTEM GROUNDING
ELECTRICAL 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
EMF RF FIELD & FREQUENCY DEFINITIONS

ELECTRICAL GENERATORS
ELECTRICAL GROUND SYSTEM INSPECTION

ENERGY SAVINGS in buildings

FEDERAL PACIFIC FPE HAZARDS
FIRE SAFETY Checklist, CPSC

GENERATORS, ELECTRICAL
GFCI PROTECTION,Testing GFCIs AFCIs

HEATING COST FUEL & BTU Cost Table
HEAT, ELECTRIC
HEAT TAPE USAGE GUIDE
Hertz - Definitions of KHz MHz GHz THz

KNOB & TUBE WIRING

LIGHTING, INTERIOR GUIDE

LIGHTNING PROTECTION SYSTEMS
LOW VOLTAGE BUILDING WIRING
MAIN DISCONNECT
  MAIN SWITCH LOCATION
  MAIN SWITCH
MAIN DISCONNECT AMPACITY
MULTI-WIRE CIRCUITS
MURRAY SIEMENS Recall

PHOTOVOLTAIC POWER SYSTEMS
PUSHMATIC - BULLDOG PANELS

REMOTE ELECTRIC POWER, PHOTOVOLTAIC
RUST in ELECTRICAL PANELS

SAFETY FOR ELECTRICAL INSPECTORS

SE CABLE SIZES vs AMPS
SIEMENS MURRAY Recall

SOLAR ENERGY SYSTEMS
SQUARE-D RECALLS

UNDERGROUND SERVICE LATERALS
VOLTAGE MEASUREMENT EQUIPMENT

WIND ENERGY SYSTEMS
WIND TURBINES & LIGHTNING

ZINSCO SYLVANIA ELECTRICAL PANELS

More Information

Unsafe sub panel bonded ground and neutral (C) Daniel Friedman Main Electrical Disconnect Switch & Switch Location
InspectAPedia®  -    

  • How to inspect the main electrical disconnect - the "main switch" for defects
  • Electrical service switch or panel location errors
  • Requirement for main disconnect switch in electrical panels
  • The six breaker rule as main electrical panel disconnect
  • Online Course on how to inspect electrical panels
  • Questions & answers about the main power switch or main disconnect switch at electrical panels
InspectAPedia offers impartial, unbiased advice without conflicts of interest. We will block advertisements which we discover or readers inform us are associated with bad business practices, false-advertising, or junk science. Our contact info is at InspectAPedia.com/Contact.htm.

This article summarizes inspection of the main electrical switch - the main switch at buildings and also outlines other electrical panel and switch defects that can be found by visual inspection. 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 2012 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website.

Inspecting the Residential Electrical Main Disconnect Panel or "Box" for Defects

Readers of this section should also see ELECTRIC PANEL AMPACITY.

  • Main control center for house
  • Integrated or separate service disconnect (main breaker or fuses) - need main disconnect if more than 6 switches

Electrical Service Box Location Defects

  • OK indoors our outside (if weather tight)
  • NOT OK bathroom, clothes closet, kitchen cabinets
  • Should Be at eye level, easily accessible, with 3 ft. working clearance

Inspecting the Electric Service Panel & Main Disconnect Switch for Condition Defects

Unsafe sub panel bonded ground and neutral (C) Daniel FriedmanThe Implications: electrical shock or fire

  • Missing Main Disconnect Switch - note that at some installations the main disconnect may be located separately from the main electrical panel, particularly if the main electrical panel is distant from the electric meter (NEC Ref 1).
  • No main disconnect switch in electrical panels with six or more breakers. If the "six-breaker" rule is allowed locally, the six switches must be together in the same panel enclosure.
    That is, if six or fewer breakers are in the main panel, that panel can be counted as a service disconnect (NEC Ref 2).
    We and others believe this requirement originated with fire fighting departments, to assure that no more than six manual operations would be required to turn off electrical power in an emergency. Note that local jurisdictions and codes may require that a single main switch be provided. - Ed.
  • Poor access to the electrical panel; panel not secured
  • Rust, corrosion in the electrical panel or main disconnect
  • Overheating signs in the electrical panel or main disconnect enclosure
  • Over fusing or box rating too small for the service entry wiring or building or circuit load
  • Inappropriate. mounting surface for the electrical panel or main disconnect / not secure
  • Damaged electrical panel or main disconnect parts
  • Poor electrical panel or main disconnect connections, poor wiring
  • Illegal taps at the electrical panel or main disconnect
  • Neutral wire (grounded conductor) defects such as bonding the neutral and ground in a sub panel (see photo and see Case History:Loss of Neutral Shocks Homeowner)
  • Fused, bypasses box, fused upstream
  • Obsolete electrical panel, breakers, disconnect, equipment or unsafe equipment - examples:
    Classified CIRCUIT BREAKER WARNING
    FEDERAL PACIFIC FPE HAZARDS
    SQUARE-D RECALLS
    ZINSCO / SYLVANIA HAZARDS,

  • Exterior, electrical panel or main disconnect not weather tight
  • Specific Electrical Panel Product Defects, see additional articles listed at left and below

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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
ELECTRICAL INSPECTION SAFETY
ELECTRICAL VOCABULARY
ELECTRICAL SERVICE DROP
  WIRE CLEARANCES
ELECTRICAL SERVICE ENTRY WIRING
  DETERMINE SERVICE AMPACITY
  TABLE OF SERVICE AMPACITY
  SERVICE AMPACITY DEFECTS
ELECTRICAL GROUND SYSTEM INSPECTION
  TABLE OF GROUND WIRE SIZES
  ELECTRICAL SYSTEM GROUNDING
  SERVICE GROUNDING DEFECTS
MAIN DISCONNECT
  MAIN SWITCH LOCATION
  MAIN SWITCH

ELECTRICAL GROUND SYSTEM INSPECTION
  Gas Piping Ground Bond
  TABLE OF GROUND WIRE SIZES
  Old House Electrical Grounding
  False Ground at Receptacles
  False Neutral Connections
  Case History: Double Fault Leads to Loss of Power
  Case History:Loss of Neutral Shocks Homeowner
  Electrical Service Grounding Checklist
  Why Grounding is Needed
  ELECTRICAL SYSTEM GROUNDING
  SERVICE GROUNDING DEFECTS
  TABLE OF GROUND WIRE SIZES
  Old House Electrical Grounding
ELECTRICAL 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

  • U.S. National Electrical Code, NEC Reference (1): [QUOTING 2008 NEC]
    National Electric Code is Article 225 Part II.
    225.31 Disconnecting Means. Means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure.
    225.32 Location. The disconnecting means shall be installed either inside or outside of the building or structure served or where the conductors pass through the building or structure. The disconnecting means shall be at a readily accessible location nearest the point of entrance of the conductors. For the purposes of this section, the
    requirements in 230.6 shall be utilized.
    VI. Service Equipment - Disconnecting Means
    230.70 General. Means shall be provided to disconnect all conductors in a building or other structure from the service entrance conductors.
    (A) Location. The· service disconnecting means shall be installed in accordance with 230.70(A)(l), (A)(2), and
    (A)(3).
    (1) Readily Accessible Location. The service disconnecting means shall be installed at a readily accessible location
    either outside of a building or structure or inside nearest the point of entrance of the service conductors.
    (2) Bathrooms. Service disconnecting means shall not be installed in bathrooms.
    (3) Remote Control. Where a remote control device(s) is used to actuate the service disconnecting means, the service disconnecting means shall be located in accordance with 230.70(A)(1).
    (D) Marking. Each service disconnect shall be permanently marked to identify it as a service disconnect.
    (C) Suitable for Use. Each service disconnecting means shall be suitable for the prevailing conditions. Service
    equipment installed in hazardous (classified) locations shall comply with the requirements of Articles 500 through 517
  • U.S. National Electrical Code NEC Reference (2): Requirement for main circuit breaker if more than six switches in the panel: See NEC Section 230-71.
    Article 225: A readily accessible disconnect is required at the remote building, located either outside or nearest the point of entrance inside [225-8]. There shall be no more than six disconnects mounted in a single enclosure, or up to six separate enclosures [230-71]. The disconnects must be grouped and each disconnect must be marked to indicate the load served [110-22 and 230-72].
  • 1993 NEC (Quoting from Orlando Florida Code of Ordinances, web search 01/18/2011, original source:
    http://search.municode.com/html/13349/level3/TITIICICO_
    CH22ELCO_ARTIIINAELCOAM.html#TITIICICO_CH22ELCO_
    ARTIIINAELCOAM_S22.49SE230-71NAELCOAM

    Section 230-71 of the National Electrical Code of 1993 is amended to read as follows: (a) No building shall have more than six (6) operations of the hand for a main disconnecting means. (b) Commercial buildings. The 100A or over service disconnecting means shall comply with Article 230 of the National Electrical Code and shall be installed on the outside of the building as near the point of entrance of service wires as possible considering the type of building and accessibility in case of fire or other reason for opening the service switch and disconnecting the building. Upon special application to the inspecting authority, before any work is started, approval may be granted for the meter and/or service disconnecting means to be installed inside the building if accessible and available for meter reading, servicing and disconnecting in case of emergencies. (c) On commercial or residential buildings, if the service disconnecting means is not readily apparent on the exterior of the building, it shall be properly indicated by a reasonable sign constructed of permanent materials with no less than one and one-half (1½) inches high letters designating its exact location. The sign shall be located on the exterior of the building at the service doorway. If the service disconnecting means is located at a point that is not accessible and available for meter reading, servicing, and disconnecting in case of emergencies, there shall be a shunt trip switch installed and so noted as above. (d) Where a property comprises more than one building under single management or in multiple occupancy buildings, a separate switch at service entrance equipment for each building must be installed (it may be a toggle switch) to disconnect the "House Lighting" circuits. This switch may be locked. It shall have an indicating sign at or on the switch.
  • Outside electrical service feeder wires: see Article 225, not Article 230 (Service conductors).
  • * Safety Hazards and Safe Inspection Procedures for Electrical and Home Inspectors at Residential Electric Panels

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

  • Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
  • Recommended books on electrical inspection, electrical wiring, electrical problem diagnosis, and electrical repair can be found in the Electrical Books section of the InspectAPedia Bookstore. (courtesy of Amazon.com)
  • * Safety Hazards and Safe Inspection Procedures for Electrical and Home Inspectors at Residential Electric Panels
  • 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
  • Rust and Corrosion in Electrical Panels, A Study and Report on Frequency and Cause for Electrical and Home Inspectors at Residential Electric Panels
  • "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.
  • Electrical System & Wiring Hazard Inspection, Detection, Cause, Remedy, Prevention - Main Electrical Page
  • ...
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