Electric Codes For Outbuildings/detached Garages

bergenbldr

A question about electric codes for outbuildings/detached garages.Specificly are exposed /romex plastic boxs ok or do i need to run conduit . Also would bx/metal boxes be ok,these building are not sheetrocked so all wiring is exposed to interior of building.

mdshunk

That's a pretty straightforward question....

334.15 Exposed Work. In exposed work, except as provided
in 300.11(A), the cable shall be installed as specified
in 334.15(A) through (C).
(A) To Follow Surface. The cable shall closely follow the
surface of the building finish or of running boards.
(B) Protection from Physical Damage. The cable shall be
protected from physical damage where necessary by rigid
metal conduit, intermediate metal conduit, electrical metallic
tubing, Schedule 80 PVC rigid nonmetallic conduit, or
other approved means. Where passing through a floor, the
cable shall be enclosed in rigid metal conduit, intermediate
metal conduit, electrical metallic tubing, Schedule 80 PVC
rigid nonmetallic conduit, or other approved means extending
at least 150 mm (6 in.) above the floor.
Where Type NMC cable is installed in shallow chases
in masonry, concrete, or adobe, the cable shall be protected
against nails or screws by a steel plate at least 1.59 mm (1⁄16
in.) thick and covered with plaster, adobe, or similar finish.
(C) In Unfinished Basements. Where the cable is run at
angles with joists in unfinished basements, it shall be permissible
to secure cables not smaller than two 6 AWG or
three 8 AWG conductors directly to the lower edges of the
joists. Smaller cables shall be run either through bored
holes in joists or on running boards.

To summarize, if the cable will be exposed to physical damage, you need to protect it somehow. This may cause you to choose a conduit wiring system.

Additionally, if this is a non residential outbuilding, the following also applies (which does not allow Romex):

ARTICLE 334 NONMETALLIC-SHEATHED CABLE: TYPES NM, NMC, AND NMS
334.12 Uses Not Permitted.
(A) Types NM, NMC, and NMS. Types NM, NMC, and
NMS cables shall not be permitted under the following
conditions or in the following locations:
(1) In Type I or II construction unless permitted to be
Types III, IV, or V construction.
(2) In non-dwelling construction unless the cables are
concealed within walls, floors, or ceilings that provide
a thermal barrier of material that has at least a 15-
minute finish rating as identified in listings of firerated
assemblies
FPN: Building constructions are defined in NFPA 5000™-
2003, Building Construction and Safety Code™, or the applicable
building code.

K2

Thats why you get 6 different inspectors and 6 different interpretations of the code. I've been in construction for 35 years and have worked with people from all over U.S. and have a Commercial GC. license and an electrical license. What the flip is a running board????? > thanks for posting MD. Even though I think the people who write this *^&** never worked for a living I guess i still will have to learn it. RT

mdshunk

A running board is one option for running perpendicular cables on the undersides of joists in a unfinished basement. Normally, we'd run them through bored holes. On occasion, in very old homes, the floor joists are made of native timbers or logs with odd spacing. These are often undersized and spaced far apart. Drilling them would only add to the mess. In this situation, you'd attach a running board to the undersides of the joists and staple the cables to the running board. This can be anything, but normally it's a 1x4 or something along those lines.

Rob, seriously, I'm not sure where the confusion comes in. This posted code section is really clear to me. I'm not sure how you can get different interpretations. If there's something else that puzzles you, I'll take a stab at clearing it up.

K2

Well i wish you could come visit our local building dept. and get thoise boys straightened out. We have about 15 electrical inspectors, (from all over the country), and they don't seem to agree on anything. And if you like, you can get the building inspectors to agree. The plumbing and mech., inspectors seem to agree, and I'm not sure why that is. My wife is retired as a health inspector, (with state statutes and enforcement powers), and they never agreed. Maybe it's the altitude. I hang out with several of the inspectors at the gym and they always tell me the codes are subject to interpretation. (They also tell me of the discussions at the shop between 7:30 AND 9AM ,when they hit the road). > Sorry, but 20 years of banging nails in 4 states. A board is 1x something, 1x2, 1x4, 1x12, 1x20. Can't be a 2x. But that is getting a little to picky for an electrician so i'll drop that as a confusion. > i do enjoy your posts and learn more here than at work.Thanks RT.