Using Romex® and Conduit Wiring in Exposed Locations

Romex 12/2 NM Wire
Romex 12/2 NM Wire. via Amazon

A city electrical inspector indicated to one of my readers that the Romex wiring in her basement was not up to code and that conduit must be installed. Why would the inspector say this?

Romex® Must Be Protected

Romex wiring is simply plastic-coated wiring (typically 10-, 12-, or 14-gauge) wrapped in another plastic sheathing. This outer plastic sheathing does not provide any kind of protection against punctures, perforations, lacerations, or any other harm that may very well come to electrical wiring in residences.

What Kind of Protection?

Because of this, electrical codes dictate that any type of non-metallic wiring, Romex included, be protected. The protection usually comes in the form of auguring holes in the studs of walls or the joists of floors and running the wiring through those holes.

Basements Often Have Exposed Surfaces

Older basements tend to have exposed masonry, or brick, surfaces. If you intend to run electrical wiring along this exposed masonry, you must use conduit.

Running Romex In Conduit

Why not run NM wire like Romex through conduit?  This is not accepted practice.

Conduit protects loose THHN wires.

Romex Can Be Used in Basements

There are two alternatives, if you wish to use Romex:

  • If you have a newer basement or an older basement that has been remodeled, you may have walls built up against the masonry surfaces. These walls, provided they are full-size and made of 2x4's and faced with drywall, provide enough protection to run Romex® through.
  • Look upward: Romex wiring can also be run through the joists of the floor above.

Use Conduit If the Wiring Must Be Exposed

You may decide that it will simply cost too much to build up walls for wiring or perhaps to tear out an existing basement ceiling to gain access to the joists above. In this case, you may find it easier and cheaper to hire an electrician to run conduit along the exposed masonry walls.