Could someone give me some clarification on the permitted use of NM in concrete, steel and glass high rise residential structures along the beach here in Florida? Is it true that the 2011 NEC permits this now? I am not sure about the construction class (I-V) of these structures. Thanks.
NM use in high-rise
- Thread starter larrykimb
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
It all depends on the classification of the structure by the building inspections dept. The number of floors limitation disappeared a few cycles ago. I would warn you that nm cannot be used exposed in dropped ceilings in other than one and two family dwellings. 334.12(2)
Hendrix
Senior Member
- Location
- New England
Then, the chances are you cannot use it.
- Location
- Logan, Utah
jaylectricity
Senior Member
- Location
- Massachusetts
- Occupation
- licensed journeyman electrician
You can if you install it in a raceway under the 2011 NEC.See 334.10(5).
Chris
Which pretty much defeats the purpose of running NM in this situation.
- Location
- Logan, Utah
It seems that our County chief electrical inspector told one condo owner that NM cable could be used in his Class I construction high-rise if the new wiring was only taps off existing circuits and not a home run. Could it be that it is up to local inspection authorities how to interpret this?
It is always up to the AHJ to interpret the code. Also, if the jurisdiction has adopted ammendments to the NEC that may come into play.
Pete
As stated earlier nm is not approved to be ran above suspended ceiling in a commercial building. The ahj may have made allowances for this to take place, but if it is a plenum ceiling, the fire marshal may have something to say about that. I don't believe nm is plenum rated, thus it is installed contrary to its ul listing. Feel free to correct me if I am wrong on that one.
- Occupation
- Licensed Electrician
I would say you are correct, but I don't know if it has anything to do with plenum ratings. 334.12 prohibits NM exposed above a drop ceiling in anything other than dwellings.
I have run it is joist bays of a wood framed commercial building and covered the bay with drywall.
I have run it is joist bays of a wood framed commercial building and covered the bay with drywall.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Correct me if I'm wrong but I believe this was some political trade off between the manufactures who wanted the 3 floor limitation removed with the not allowing it above a drop ceiling in commercial, I feel today as I did back then that this was so wrong to make laws or codes in this fashion, show me the scientific proof that NM is dangerous in these installation, not because you want to play around with making manufactures happy.:rant:
Sierrasparky
Senior Member
- Location
- USA
- Occupation
- Electrician ,contractor
It is my opinion that there is no place for these laws that have no reasonable proof, just a great lobby from a manafacture.:happysad: :rant:
Last edited:
- Location
- Massachusetts
But the NFPA does not, and has no authority to write law.
They write a standard that each local area chooses to adopt or not.
- Location
- Logan, Utah
I agree. Each jurisdiction is free to amend the standard as they adopt it. I believe that Mass amended the rule on NM above suspended ceilings and permits it.
Chris
- Status