Electrical Wiring Methods Most People Don’t Know About

Electrical Wiring Methods Most People Don't Know About

As an electrician, I often come across homeowners who are unfamiliar with the different types of electrical wiring methods used in homes. In this article, I'll discuss several wiring methods that most people don't know about, along with their pros and cons.

Knob and Tube Wiring

Knob and tube wiring was commonly installed in homes built before 1930. This type of wiring consists of single black rubber insulated wires run through ceramic knobs mounted to wall studs and joists. The wires are separated from each other by about 1 inch using ceramic tubes.

The pros of knob and tube wiring:

The cons:

While I don't recommend leaving old knob and tube wiring in place, some homeowners choose to do so. If you have knob and tube wiring, I'd advise having it evaluated by a licensed electrician.

Armored Cable (AC)

Armored cable (AC), sometimes called BX cable, first became available in the 1920s. It consists of two or more insulated conductors wrapped in a spiral layer of steel armor. This armor provides extra protection against accidental damage compared to knob and tube and early NM cables.

The pros of armored cable:

The cons:

Armored cable is approved for some wiring applications, but NM cable has largely replaced it in modern residential wiring.

Non-metallic Sheathed Cable (NM)

Non-metallic sheathed cable (NM), commonly called Romex, has been used since the 1960s. It contains two to four insulated copper wires wrapped in a protective plastic sheath. Unlike armored cable, it does not contain any metal.

The pros of NM cable:

The cons:

NM cable is the most common wiring method found in modern homes. It comes in various sizes suitable for 15 to 50 amp electrical circuits.

Conduit Wiring Methods

Conduit refers to thin-walled tubing or pipe used to enclose and protect electrical wires. The conduit itself does not contain the conductors inside it. Common types of conduit include:

The pros of conduit wiring:

The cons:

Conduit is more common in commercial or industrial buildings but is also useful in certain residential applications.

In Summary

The key wiring methods I've described include:

Understanding the different types of wiring allows you to make informed repair, replacement, and upgrade decisions for your home's electrical system. Let me know if you have any other questions!