Question – Basement Wiring Methods
Romex or metal cable: What should be used when wiring a basement and how is the wiring protected?
When wiring in a basement (it will run from the breaker, along the ceiling, to a first floor outlet near the floor of that level), is Romex wire OK? We have heard that you should use metal cable.
Basement Wiring – NEC Sections 336-6c, 333-11 – ATE
The concern is that the wiring is protected and not exposed to physical harm.
Other considerations include the future use of the area. You do not want to run surface wiring if the area may be finished off with sheet rock or other materials in the future.
The code states that the Romex style wiring made up of two conductors smaller than No.6, or three No.8 must be run through holes bored in joists, or on running boards which would provide protection to the wiring.
In unfinished basements, exposed runs of armored (BX) cable can be run on the undersides of joists in basements where supported on each joist and so located as not to be subject to physical damage.
In Unfinished Basements:
Where the cable is run at angles with joists in unfinished basements, it is permissible to secure cables not smaller than two No. 6 or three No. 8 conductors directly to the lower edges of the joists. Smaller Romex type cables shall either be run through bored holes in joists or on running boards.
“On Running Boards” refers to wood members such as joists, girders or supporting members. This is accomplished by following these members there by having a means for protection and anchoring.
The local inspection authority usually interprets the meaning of “subject to physical damage”. Your local building inspector enforces their “Interpretation of the Code”, thereby having the final authority.