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Joined: Aug 2003
Posts: 1,374
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Ryan_J Offline OP
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As most of you are aware, article 334.10 changed drastically in the 2002 NEC. NM cable can now be used nearly anywhere that is not required to be combustible construction (types I and II).

Example: The 150,000 square foot home depot or Lowes or super walmart down the down the street. Are these buildings required to be non-combustible? Beleive it or not, the answer is probably no.

There are many buildings that meet the criteria for an "unlimitted area building" because of fire sprinklers and large property frontage. These buildings are type "VB" construction, meaning that they could be built out of wood!

If you are in the business of designing "as-build" electrical installations, this could mean the difference of winning the bid. Make sure to check with the building department about types of construction before you commit, however.

BTW: keep in mind other aspects of the code such as health care and places of assembly, to name a few.


Ryan Jackson,
Salt Lake City
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Joined: Jan 2003
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We do 80,000 to 100,000 sq ft supermarkets in NM.

These have suspended ceilings but have hard duct HVAC returns so it is not "other space used for environmental air" MA amended the change in the 2002 NEC so that NM above a commercial suspended ceiling is still OK.

From a personal stand point I think it is a bogus installation. [Linked Image]

480 volt 3 phase roof top units fed with 12/3 NM strung through the steel joists.

Have you noticed how thin the outer jacket is getting on NM lately?

IMO it unlikely after installing thousands of feet of NM in these steel frame buildings that some of it will not be damaged.

This is starting to change more of these stores are going MC now.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Joined: Jun 2003
Posts: 681
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I used to be very opinionated about certain wiring methods, when I was less experienced than I am now. Not so much wiring experienced, but 'lifes' experiences.

Bob
I thought that Mass. was permitting the use of NM cable in high rise buildings as well. I believe that Mass. and Michigan are two states that do not have all of the restrictions of NM cable that the NEC has. I have also heard that these states have experienced 20 or so years of no real problems with NM cable in those locations.

If you were to look at the changes in the NEC for 2002 in uses permitted and not permitted for NM, You will see they have taken the building height restriction out, and removed permission to install it in commercial 'drop' ceilings.

The reason for the drop ceiling change is the results of a smoke test were reviewed and the CMP decided it was in the best interest of safety to install the new restriction.

I personally believe that NM cable installed in the proper locations is just fine. All wiring methods have their place, thats is why they are in the NEC.

Pierre


Pierre Belarge

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