Home Electrical Basics 101 – The Spruce

Your homes wiring consists of a few different types of wiring, including non-metallic cable (commonly called Romex), Bx cable, and wiring concealed in conduit. NM cable is the most common type of circuit wiring. It is suitable for use in dry, protected areas (inside stud walls, on the sides of joists, etc.) that are not subject to mechanical damage or excessive heat.

Bx cable, also known as armored cable, consists of wires running inside a flexible aluminum or steel sheath that is somewhat resistant to damage. It is commonly used where wiring for appliances, such as dishwashers and garbage disposers, is exposed.

Conduit is a rigid metal or plastic tubing that protects individual insulated wires. It is used in garages, sheds, and outdoor applications where the wiring must be protected from exposure.

Wires running inside NM cable, Bx cable, or conduit are sized according to each circuit's amperage. Wire size is given in its gauge number. The lower the gauge, the larger the wire, and the more current it can handle. For example, wiring for 20-amp circuits is 12-gauge, which is heavier than the 14-gauge wiring used for 15-amp circuits.

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Home Electrical Basics 101 - The Spruce