I've only come across one commercial building that actually had NM-B for the original wiring.. It was all wood construction also.. Usually I find NM-B in commercial by means of someone adding or moving wiring on their own & not knowing it's not allowed here...
PS... At least they didn't just lay it on top of the grid ceiling!
#108239 - 05/21/0404:30 AMRe: NM Cable As The Support.
I have to say here that I do service calls at many of these NM stores and almost never are the service calls traceable to the use of NM.
Yes MA has amended the requirement but in a way that is hard to meet in these stores.
334.12(1). Revise to read as follows:
In dropped or suspended ceilings in other than one- and two-family and multifamily dwellings, unless run so as to closely follow the surface of framing members, running boards, or the equivalent, or unless connected to luminaires (lighting fixtures) in accordance with 334.30(B)(2).
MC support requirements allows us to run between the truss which are generally five and a half feet apart, we can not do that with the "closely follow the surface" requirement of NM.
Bob Badger Construction & Maintenance Electrician Massachusetts