wiring methods

[Frontman]

Just starting out, is it permisable to wire a semi-truck repair garage in romex? There's a pit w/ a fan that constantly removes air at a rate not less than 1 CFM and I believe it meets everything else in 511.3 (A)(1)-(A)(7). If not, MC cable I suppose?

 

[George Stolz]

Why would you want to, for starters?

It's not just "1 CFM", it's "1 CFM per Square Foot."

Can you give us more of the story? What are you doing?

Edit to add: (3)(a) states a pit is Class I Div II when ventilated.

 

[Dennis Alwon]

Not Nm cable I am afraid.

334.12 Uses Not Permitted.
(A) Types NM, NMC, and NMS. Types NM, NMC, and NMS cables shall not be permitted as follows:
(1) In any dwelling or structure not specifically permitted in 334.10(1), (2), and (3)
Exception: Type NM, NMC, and NMS cable shall be permitted in Type I and II construction when installed within raceways permitted to be installed in Type I and II construction.
(2) Exposed in dropped or suspended ceilings in other than one- and two-family and multifamily dwellings
(3) As service-entrance cable
(4) In commercial garages having hazardous (classified) locations as defined in 511.3
(5) In theaters and similar locations, except where permitted in 518.4(B)
(6) In motion picture studios
(7) In storage battery rooms
(8) In hoistways or on elevators or escalators
(9) Embedded in poured cement, concrete, or aggregate
(10) In hazardous (classified) locations, except where permitted by the following:
a. 501.10(B)(3)
b. 502.10(B)(3)
c. 504.20

 

[M. D.]

Just starting out, is it permisable to wire a semi-truck repair garage in romex? There's a pit w/ a fan that constantly removes air at a rate not less than 1 CFM and I believe it meets everything else in 511.3 (A)(1)-(A)(7). If not, MC cable I suppose?

Welcome to the forum. I hope you don't mind,.. I thought I'd suggest a little reading ,..I thought this was easy to read and understand

http://www.inspectionbureau.com/guides/Commercial Garages.pdf

2. Wiring & Equipment In Classified Areas:

a. Wiring Methods ? In general, everything up to 18? above the floor (or
within 18?of the ceiling for ?lighter than air? gaseous fuels) is Class 1
Division 2. Pits and depressions below the floor are Class 1 Division 1.
Don?t want the hassles of special wiring methods?
Then stay out of those areas.

If you avoid the classified areas, any of the wiring methods in Art.
511.7 (A) (1) are OK. You may also want to avoid installing conduit under
the slab because as the conduit emerges above the floor, it passes through
classified areas, which require seals at the boundaries. Because of this and
other rules applicable to wiring in hazardous locations, ?slab work? in
repair and service areas may not be worth the effort or expense.

I also thought you might like to read this one

http://ecmweb.com/mag/electric_electrical_design_considerations/

.........Service pits, for example, have been the site of workers trapped under burning vehicles, resulting in terrible injuries and/or electrocutions due to concentrations of several flammable liquids and water.............