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Sketch explaining electrical AMPS (C) Carson Dunlop AssociatesElectrical System Defects List & Home Inspection Education

This article lists significant Electrical System defects, definitions, and home inspection education topics. This article series, beginning at BUILDING DEFECTS LISTS, provides lists of common building defects and basic defect knowledge that also outline recommended curriculum content for home inspector education.

The building defects and inspection points listed in these articles also guide homeowners and home buyers to building areas that merit careful attention and often point areas of safety concern or important maintenance and repair tasks. Page top sketch provided courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

- Daniel Friedman, Publisher/Editor/Author - See WHO ARE WE?

Home Inspection Education Curriculum - Electrical

3.0   ELECTRICAL System Inspection Requirements & Defects List

3.1   Service Drop and Service Entrance

3.1.1 Knowledge Base

1.    Describe the function of the electrical system in the home.

2.    Describe the location and function of the service drop and service entrance.

3.    Describe two types of service drops (overhead and underground).

4.    Describe two types of service entrance (conduit and cable).

5.    List the common materials used for service entrance conductors (copper, aluminum).

6.   Describe the features of  adequate installation and repair technique for service drops and service entrance conduit or cable.

7.    Define the following terms:

Service drop, service lateral, service entrance conductor, over-current device (over-current protection device), amp (amperes), volt (voltage), electrical potential (electromotive force), ohms (resistance), ungrounded conductor (black, hot, red, hot), grounded conductor (white, neutral, identified conductor), grounding conductor (green, bare, ground), bonding conductor, alternating current versus direct current, insulator versus conductor, 120 versus 240 volts, impedance, resistor, watt, kilowatt, kilowatt-hour ( kWh), electrical circuit, short circuit, fuse, breaker, ground fault, overload, parallel circuit, series circuit, drip loop, masthead (service cap, entrance cap, pothead?? Not home inspectors!, weather head, service head), three phase electrical system (does three phase matter to home inspectors?) On rare occasions these can be found.  JDG\, service  capacity, service  panel, distribution panel, combination panel.

8. Write the formula for voltage as a function of current and resistance. Write the formula for power as a function of voltage and current, and be able to rearrange both formulas to solve for any variable. This is really not required to be a home inspector, but the RDS includes theory Conversion fomula for KW to BTU..JDG

9. Understand the term load calculation with respect to sizing house electrical services (performing load calculations is not part of a home inspection).

10.   Identify the codes and standards which apply to electrical service drop and service entrance in your area.

3.1.2 Inspection Skills:

1.    Describe the inspection procedure for service drop and service entrance systems.

2.    Describe the procedure for identifying service  capacity and evaluating service adequacy.

3.    Identify the common defects listed on the next page.

4.    Describe the implication of each of the defects above.

5.    Identify the safety issues for the inspector and the occupant of the house (electrical shock, fire).

6.    Communicate findings to client verbally and in writing, recommending corrective action where needed.   

Electrical Service Drop & Electrical Service Entry Typical Defects List    

Electrical Service Drop or Service Lateral Defects List

• Branches, vines interfering with wires

• Damaged, frayed wires

• Excessive height

•  Clearance over roofs

•  Clearance over walking areas

•  Clearance over roadways

•  Clearance over driveways

•  Clearance over decks, balconies and pools

• Inadequate window or door clearance

• Poor connection to service conductors

Electric Meter & Meter Base

The electric meter base may or may not include a main electrical power switch.

External, visible defects at the electric meter such as

See details at

Electrical Service Capacity Defects

Electrical Service Conductors, SEC, or Entrance Wires & Cables Defects List

• Conduit or cable damaged

• Conduit or cable covered by siding or roof penetrations for additions.  JDG

• Conduit or cable not weathertight

• Drip loop too low (touching roof)

• Mast rust

• Mast bent

• Mast rot

• Mast loose

• Mast not weathertight

• Masthead not weathertight

• No masthead

• No drip loop

• Wires too close to roof


3.2  Electrial Service  Panel, Grounding & Panel Inspection

3.2.1 Knowledge Base for Electrical Panels

1.    Describe the function of the service  panel

2.    Describe the function of the grounding system.

3.    Describe the function of distribution panels.

4.    Describe three types of service  panels (fuse, breaker, combination).

5.    List the materials and components of service  panels.

6.    Describe the features of  adequate installation and repair techniques for service boxes.

7.    Describe the materials and components of an electrical grounding system.

8.    Describe the features of  adequate installation and repair techniques for house grounding systems including systems that terminate at ? water pipes, metal rods in ground, UFER ground (concrete encased grounding electrode), grounding plates or rings, metal building frames, well casings.

Note: The omission of UFER grounding may be particularly serious in areas of dry soils.

See UFER explained

at ELECTRICAL DEFINITIONS and see a discussion of grounding connection in the footing or slab omission in

at ELECTRICAL GROUND REQUIREMENTS.

9.    Describe the types of distribution panels (fuses, breakers, combination).

10.   List the typical materials and components of distribution panels.

11.   Differentiate between main distribution panels and sub-panels.

12.   Describe the features of good installation and repair techniques for main and sub-panels.

13.   Define the following terms:

Service box (service equipment, main panel, service panel these are all the same to me??), distribution panel, combination panel, grounding equipment, over-current device, electrical meter, line and load, carrier current controller, bonding, dielectric connector, type S fuse, type D fuse, type P fuse, distribution panel (service panel, , subpanel, fuse box, fuse panel, , ), pull-out fuse box, overfusing, cartridge fuse, fused neutral, double tap (double lugging), pig tailing, multi-wire branch circuit, bus bar, linked fuse, linked breaker, single throw and double throw breaker, single pole and double pole breaker.

14.   When is a service  panel not required?

15.   Identify the codes or standards which apply to electrical service boxes, grounding systems and panels in your area.


3.2.2 Inspection Skills for Electrical Panels

1.    Describe the inspection procedure for:

2.    Identify the common defects listed on the next page.

3.    Describe the implication of each defect.

4.    Identify the safety issues for the inspector and occupant of the house (electrical shock, fire).

5.    Communicate findings to client verbally and in writing, recommending corrective action where needed.

Electrical Service Panel (Main Panel) Defects List

Electrical Distribution Panel Defects List

Electrical Grounding System Defects List

• Connections not accessible  

• Corroded grounding conductor

• Grounding electrode rod cut or disconnected..JDG   

• Missing        

• Neutral bonded to grounding conductor wire  downstream of service box          

• Neutral not bonded to ground at box

• No jumper for meters and valves

• No ground for subpanel

• Poor connections

• Spliced grounding conductor wire

• Undersized grounding conductor wire

• Wire attached to plastic pipe

• Wire attached to abandoned pipe

Electrical Wire Defects & Damage Checklist

3.3   The Electrical Distribution System - Wiring Defects

3.3.1 Knowledge Base

1.    Describe the function of the electrical distribution system in a house.

2.    List the materials and components of the electrical distribution system including the common conductor types (conventional copper, aluminum and knob-and-tube).

3.    Describe the features of  adequate installation and repair technique for the distribution system including wiring, lights, outlets, switches, and junction boxes.

4.    Define the following terms: branch circuit conductor, polarity, ground fault circuit interrupter, NMW cable, NMD cable, BX cable, solder-dipped wire, wire insulation versus sheathing , solid and stranded wire (including typical sizes for each), wire gauge (including AWG and MCM), dedicated circuits, anti-oxidant, CuAl  JDG, CO/ALR, COPALUM, wire nut, (solderless connector, twist-on connector), creep with respect to aluminum wire, potlight (recessed light fixture, high-hat light fixture), three way switch, four way switch, two-pin receptacle, three-pin receptacle.

5.    Identify the codes or standards which apply to the electrical distribution system in your area.

3.3.2 Inspection Skills for Building Electrical Wiring


1.    Describe the inspection procedure for the distribution system including the conductors, lights, outlets, switches and junction boxes, including central air-conditioner circuits.

2. Describe the special inspection issues related to aluminum wiring.

3. Identify the common defects listed on the next page.

4.    Describe the implication of each defect .

5.    Identify the safety issues for the inspector and the occupant of the house(electric shock and fire).

6.    Communicate findings to client verbally and in writing, recommending corrective action where needed.

Electrical DISTRIBUTION SYSTEM, Wiring, Receptacles, Lights & Fixtures, TYPICAL DEFECTS

Electrical Lights, Lighting Defects

Electrical Switch Defects List

Electrical Wiring Defects

• Abandoned wire

• Buried cable

• Damaged

• Exposed on walls or ceilings

• Exposed in attics

• Improper color coding

• In steel studs without protection

• Indoor cable used outdoors

• Loose connections

• Missing

• Not well secured                          

• Open splices

• Overhead wires not stranded

• Permanent wiring used as extension cord

• Too close to ducts, pipes, chimneys, etc.

• Too close to edge of studs or joists

• Under carpets

• Undersized wire 

• Wrong type

Electrical Junction Box Defects List

Knob & Tube Electrical Wiring Defects List

• Buried in insulation

• Connections need boxes

• Conventional lights in wet areas

• Fused neutrals

• Wire insulation or sheathing brittle

Aluminum Electrical Wiring Defects List

Electrical Receptacle Defects Checklist

Outdoor Electrical Wiring Defects Checklist                

• Buried wire 

• Extension cords powering exterior outlets

• Garage door opener connected to extension cord

• Indoor wire used outdoors

• Not suitable for use

• Solid wire run overhead

• Wires not well secured to walls

• Wires too close to grade

• Wires run on roof surfaces

• Wires through gutters or downspouts

Use the Search Box at the top or bottom of these pages to find in-depth information about building, energy savings, and indoor environment inspection, diagnosis and repair at this website. Watch out: these inspection lists do not list all possible defects for the systems discussed, and ot all home or building inspectors will examine all of the items listed here. CONTACT us to suggest corrections or additions to articles at this website.


These curriculae and building defect lists are based on smilar curriculum documents first prepared by Joe Scaduto, an ASHI member who prepared course material for Northeastern University's Building Inspection Certificate program in 1988, subsequently by DF, InspectApedia's editor, for New York University ca 1988 and later, with others, recommended to ASHI, the American Society of Home Inspectors.

ASHI did not adopt this material though currently that association as well as others offer extensive HOME INSPECTOR EDUCATION material. The curriculum and lists of defects are informed by additional analysis of the process of home inspection that was developed beginning Calgary, AB for Canadian and U.S. home inspector education and certification examinations in 1997.

Other early contributors to home inspection education in the U.S. and Canada include Dr. Jess Aronstein, Alan Carson, Mike Casey, Mark Cramer, John Cox, Dwight Barnett, Douglas Hansen, Rick Heyl, Larry Hoytt, Bill Merrill, Kevin O'Malley, Dennis Robitalille, Keith Peddie, Pat Porzio, Roger Robinson.


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