Sorry to keep bombarding with questions, but after a long "drought"(probably spelled that wrong), work has started to come again. I have a big industrial building that has a break room built in the middle of it. It used to be an office area.It has some romex already dropped down the walls from metal junction boxes on top. Is this code compliant. Seems like it would be alright, since it is not exposed to the rest of the building. It is framed up with bathrooms on the outside perimeter of it. Don't know exactly what they will be using the building for right now, it is just an empty space they are getting ready to move into. Thanks

334.10 of 2008 NEC:

334.10 Uses Permitted.
Type NM, Type NMC, and Type NMS cables shall be permitted to be used in the following:
(1) One- and two-family dwellings.
(2) Multifamily dwellings permitted to be of Types III, IV, and V construction except as prohibited in 334.12.
(3) Other structures permitted to be of Types III, IV, and V construction except as prohibited in 334.12. Cables shall be 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 fire-rated assemblies.

There are FPNs and info on where to find the structure types within the text within the Handbook, and probably the Code book

Thanks John.

The real issue is construction type, "industrial" and "Commercial" are really meaningless in this decision.
I have seen industrial or commercial zoning in buildings that were clearly type III or even type V in some strip malls.

Greg:
I know what you mean.

When I had my EC hat on, no NM (except occasional temps) was installed in any comm jobs that I did. BX, AC, MC, and we were extatic when the aluminum jacket MC was introduced.

Industrial was EMT, RGC, IMC.

Physical protection issues usually drive tougher wiring methods anyway but if this is in a wall romex can be OK if it is not Type I or II.

John,


Up here they use RX in com. jobs all the time as long as the building isn't type I or II. Most EC's will use #12 ga wire, but I have seen #14 wire in there too.

Somebody was napping when they changed the rules - perhaps a decade ago.

Romex was developed for, and marketed to, the residential market. I witnessed many strident representations by NM manufacturers to UL (and the code committees) that NM was only intended for use in small, simple residential buildings with wood frames.

This is why, for decades, the NEC limited the use of NM to wood-framed residential buildings of three floors or less. Three floors is as tall as you can go with wood framing; taller buildings require different construction methods.

I can't recall exactly when the NEC was re-written (99? 02?), but the NEC eliminated the earlier language completely, and instead referred to the construction type. As the code is now written, you could wire the Sears Tower, the Pentagon, and the mall of America using Romex.

Putting this in context, this was also (coincidence?) the same time the AFCI came on the market. We've seen other restrictions placed on places where Romex is likely to be used; witness the restrictions placed on residential multi-wire circuits in the 2011 edition. Romex has also been effectively banned from crawl spaces since 2008 (damp locations).

Yet, there are still plenty of localities where the use of NM (as well as "Smurf tube") is banned from anything that's not a small home. Even PVC conduit is banned in many places, except for very specialized applications (Chicago comes to mind).

What was that change?

What are the specifications for Type 1 and 2 walls. I can't seem to see a clear definition of it by searching the web.

I consider the addition of a requirement that all circuits sharing a neutral be grouped together and be on a common-trip breaker to be a restriction on the use of multi-wire circuits.

Type 1 & 2 are basically construction materials in load bearing walls and floors that re non-combustible (no wood)

This is a link to the IBC referenced Florida Building Code

http://ecodes.cyberregs.com/cgi-exe...nonindx/ST/fl/st/b200v10/index.htm#b=603

Reno:
FRom the '11 NEC....."(D) Grouping. The ungrounded and grounded circuit conductors of each multiwire branch circuit shall be grouped by cable ties or similar means in at least one location within the panelboard or other point of origination.
Exception: The requirement for grouping shall not apply if
the circuit enters from a cable or raceway unique to the
circuit that makes the grouping obvious."

Now, with the exception, some opinions are that a xx/3 NM qualifies for the exception. Or, one tye-wrap per MWBC is not that big of a deal is it??

You're also required to land them on a a common-trip breaker -though a handle tie will suffice. No more landing the wires on whatever spaces might be handy; they have to be next to each other.

Big deal? I don't have a problem with the idea, though whether it should be a matter of code is another discussion, for another thread.

It's still a restriction, however small.

The exception clearly says if the conductors of the MWBC come in on a single cable they are "grouped".



As for the paired breakers, it sounds more reasonable than a lot of new code rules we have seen. I always wondered why this wasn't a code rule. It certainly avoids confusion a few years down the road.
These are both things conscientious electricians have always done.