Type NM cable is proposed for the branch circuits of a multifamily dwelling. What determines whether that use is permitted?
- AThe number of stories, because the cable is limited to buildings of three floors or fewer above grade
Story count is a building code concept that influences the construction type but is not the Code test. A three-story building of noncombustible construction is still outside the permitted uses.
- The construction type of the building, since the cable is limited to Types III, IV, and V construction
- CThe ampere rating of the circuits, because the cable is limited to branch circuits of 20 amperes or less
Circuit rating has nothing to do with where this cable may be used. The cable is commonly used on circuits well above 20 amperes within its permitted occupancies.
- DWhether the building is fully sprinklered, because a sprinkler system permits the cable in any construction type
Sprinklers may affect the building code construction classification, but there is no Code provision that lets a sprinkler system extend this cable into any construction type.
Why B is correct
The uses permitted section ties this cable to construction type as classified by the building code. That makes the architect's construction type on the cover sheet the controlling fact, not the story count or the occupancy label. It is also why the same cable is routine in wood-framed garden apartments and prohibited in a concrete and steel high-rise.
What this question is testing
The item tests whether the candidate knows that a wiring method allowance can depend on a building code classification rather than on an electrical characteristic, and can identify which fact controls.
On the job
This is a bid-stage question. Estimators who price cable on a building that turns out to be Type I or II construction lose the difference to conduit and wire, and the discovery usually comes at submittal review. Reading the construction type off the architectural cover sheet before pricing is the habit that avoids it. On mixed projects it can vary between the podium and the wood-framed floors above, so the answer may differ within one building.
Memory technique
Wood frame yes, steel and concrete no. Construction type decides.
Exam tip
When a cable article references construction types, go find the architect's construction type before you assume anything.
Where to look it up
Look at the uses permitted and uses not permitted sections at the front of the nonmetallic-sheathed cable article.