Home Inspector Electrical Encyclopedia

Electrical Encyclopedia

Aluminum Wiring

Aluminum wiring is often used for the service entrance conductors and for large gauge wiring to major appliances such as electric clothes dryers, central air-conditioning, electric oven, etc. Aluminum wiring for such applications is quite satisfactory; however, aluminum wiring installed as branch circuits for general lighting, electrical switches and receptacle outlets, small appliances, etc. may be hazardous and certain modifications are recommended for these applications.

Ampere

Amperes, or amps, is a measure of the capacity of an electrical system. The typical minimum requirement is 100 amps; if a home is larger, or has central air-conditioning or electric heat, 150 to 200 amps is recommended.

Branch Circuit

A branch circuit is the wiring from a fuse or circuit breaker in an electrical service panel that provides electricity to particular electrical switches, outlets, junction boxes, etc.

BX Wiring

BX wiring, or armored cable, is a type of wiring that is installed in a house. This type of wiring is enclosed in a metallic sheathing and is more resistant to damage than Romex wiring.

Circuit

An electrical circuit is a flow of electricity from a supply source to one or more terminals, such as electrical outlets, switches, appliances, etc.

Circuit Breaker

An over current protection device that is designed to automatically cut off the flow of electricity when the flow of current through the circuit breaker exceeds its rated capacity. Unlike most fuses which require replacement when they are overloaded, a circuit breaker can be reset much like a switch.

Conductor

A conductor is a wire that conveys electricity.

Copper Wiring

Copper wiring is the most common type of metal used for wiring and can be either BX or Romex or enclosed in conduit.

Doubled Up Conductors

One conductor should be terminated on a service panel fuse or circuit breaker lug unless the lug is specially designed to accept more than one conductor; all improper double connections must be eliminated by a licensed electrician by relocating the affected conductors to a new position in the service panel.

Ground Fault Circuit Interrupter

Ground fault circuit interrupters, GFCI units, are installed in areas that are subject to water, such as bathrooms, kitchens, garages, unfinished basements, outdoors, etc. GFCI units are designed to protect persons from hazardous ground faults by automatically turning off the electricity to the unit when a fault is detected.

Fuse

An over current protection safety device that is designed to automatically cut off the flow of electricity when the flow of current through the fuse exceeds its rated capacity.

Ground

Electrical systems must be properly grounded to provide a safe service. System conductors are typically secured to driven ground rods or water service pipes.

Knockouts

Knockouts, or twist outs, in an electrical service panel should not be removed unless the position is filled; missing knockouts present a safety hazard if a person places a finger into the the service panel through the knockout. Therefore, all missing knockouts should be replaced with plastic fillers or with circuit breakers.

Knob-and-Tube Wiring

Knob-and tube wiring is an outdated type of wiring that has been replaced by Romex and BX wiring. This outdated type of wiring can be hazardous and replacement with modern wiring is typically recommended.

Open Ground

An electrical receptacle outlet with an open ground condition is an outlet with an improper wiring condition and such conditions may be hazardous and repair is required.

Open Junction Box

Electrical junction boxes must have proper covers; when a junction box does not have a cover, it is noted as an open junction box.

Over Fused Circuit

An over fused circuit is a circuit that is protected from over current by a fuse or circuit breaker that is over sized for the capacity of the circuit conductors. This is a hazardous condition that can result in overheating of the conductors and may result in an electrical fire.

Overhead Service

An overhead electrical service is a service where the conductors approach a home overhead.

Over Loaded Circuit

An overloaded circuit is a branch circuit that has too many electrical outlets, switches, etc. connected to it and therefore, the fuse or circuit breaker associated with this circuit is likely to trip. An overloaded circuit may have to be split into two circuits if the fuse blows, or the circuit breaker trips too often.

Reversed Polarity

An electrical receptacle outlet with a reversed polarity condition is an outlet with an improper wiring condition and such conditions may be hazardous and repair is required.

Romex Wiring

Romex wiring, or nonmetallic sheathed wiring, is a type of wiring that is installed in a house. This type of wiring is widely utilized but is less resistant to damage than BX wiring.

Service

The conductors and equipment for delivering electricity from the electrical supply system to the wiring system of a house.

Service Drop

The overhead service connectors from the utility pole to the house.

Service Panel

The service panel is the center of the electrical service in the house; the service panel is the location of the electrical circuit breakers or fuses.

Short Circuit

An improper connection between the hot and neutral wires of a circuit can result in a short circuit defect.

Underground Service

An underground electrical service is a service where the conductors approach a home underground.

Voltage

Most home wiring is 110 volts; 220 volts is utilized for large appliances such as electric ranges, electric clothes dryers, central air-conditioning, large room air-conditioners, etc.

Weather Head

The weather head is the connection between the service drop from the utility company and the service entrance conductors.

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