Romex

[jdconner3]

In the code book it says that you can install Romex if permitted as a Type 3, 4 or 5 building, but if it is permitted as a type 1 building you can not install Romex. Although IF the building can be a type 3,4 or 5 building you can in fact install Romex. Can someone interpret this code 334 for me?

 

[A/A Fuel GTX]

In the code book it says that you can install Romex if permitted as a Type 3, 4 or 5 building, but if it is permitted as a type 1 building you can not install Romex. Although IF the building can be a type 3,4 or 5 building you can in fact install Romex. Can someone interpret this code 334 for me?

334.10 is quite clear on this. Types 1 & 2 would require NM to be installed in a raceway which IMO wouldn't be too practical.

 

[Dennis Alwon]

I am not sure what you are asking. The building type is define by the building inspection department so we generally don't have to deal with it other than being told. Generally residential and some small commercial buildings will allow nm but I would want clarification from the building inspectors.

Also understand that NM cannot be used in hung ceilings except for residential. So even if the building is classified for NM cable and there are suspended ceiling you could only use the nm inside the walls not above the ceiling

 

[david]

I am not sure what you are asking. The building type is define by the building inspection department so we generally don't have to deal with it other than being told. Generally residential and some small commercial buildings will allow nm but I would want clarification from the building inspectors.

Also understand that NM cannot be used in hung ceilings except for residential. So even if the building is classified for NM cable and there are suspended ceiling you could only use the nm inside the walls not above the ceiling

I would only add that when used in types III IV V and the building is not being used solely for dwelling units in other words non residential use it must be concealed in walls floor and ceilings.

In the building code there are differences in terminology between ceiling joist and floor joist verses rafters. Be careful the key is concealed within these spaces. Do not run it exposed in accessible rafter spaces (attics, or basements)

 

[Cavie]

I would only add that when used in types III IV V and the building is not being used solely for dwelling units in other words non residential use it must be concealed in walls floor and ceilings.

In the building code there are differences in terminology between ceiling joist and floor joist verses rafters. Be careful the key is concealed within these spaces. Do not run it exposed in accessible rafter spaces (attics, or basements)

It is allowed in attics of commercial if they are hard ceilings and not Suspended.

 

[iwire]

In the code book it says that you can install Romex if permitted as a Type 3, 4 or 5 building, but if it is permitted as a type 1 building you can not install Romex. Although IF the building can be a type 3,4 or 5 building you can in fact install Romex. Can someone interpret this code 334 for me?

We used to wire 100,000 sq ft stores constructed out of steel and concrete with NM.

We could do that because the building codes would have allowed (permitted) these buildings to be constructed out of wood. The only reason metal and block was used was due to design reasons. So we were able to use NM.

We would probably still be doing that but the code changed and said we could no longer run NM above a suspended ceiling. That made it unpractical to continue using NM.

 

[iwire]

It is allowed in attics of commercial if they are hard ceilings and not Suspended.

Yes, but not exposed.

334.10

(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 firerated
assemblies.

 

[mgookin]

I disagree with the above opinions.

If I build a single family home out of solid concrete and steel (actually very common around here in hurricane alley) I'm still calling it Type V. Otherwise the code is going to compel me to fire rate my load bearing walls, floor/ ceiling assemblies, roof assembly, etc. Imagine all the dampers, sheetrock, caulking, etc.

If that building is called Type I there's a reason for it. Type I allows unlimited height & area. So either there's something going on in that building, or it's for future expansion, or something.

My advice is go back to the principal designer and ask them to reclassify it as Type III and see where you get.

 

[iwire]

I disagree.

Building types are determined by the materials used, we don't get to call it something different.

As far as firewalls and dampers etc there may be exceptions for them just as we have for NM.

 

[GoldDigger]

I disagree.

Building types are determined by the materials used, we don't get to call it something different.

As far as firewalls and dampers etc there may be exceptions for them just as we have for NM.

Yes, but.....

Looking specifically at the language of 334.10, we see in (3) (2011):

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.

I see this as allowing NM to be used in any building classification (occupancy) which allows the construction type to be III, IV, or V, whether that construction type is in fact used or not.

Otherwise the code section would simply have said "Other structures OF Types III, IV, and V
construction.."

PS: Building types (e.g. occupancy, usage, zoning) are not determined by the construction methods used. But building construction types are.
Particular building types, as defined in other codes, are each limited to a particular set of construction types. But the building is the same in many ways, including this one, regardless of the allowed type of construction actually chosen.
Other NEC provisions apply directly to construction methods actually used (like the 15-minute fire resistance).

 

[iwire]

Yes, but.....

Looking specifically at the language of 334.10, we see in (3) (2011):



I see this as allowing NM to be used in any building classification (occupancy) which allows the construction type to be III, IV, or V, whether that construction type is in fact used or not.

Otherwise the code section would simply have said "Other structures OF Types III, IV, and V
construction.."

I agree with what you are saying but don't see it contrditing my post at all. You leave me confused.

 

[iwire]

My point was the building type classification remains the same we are just given leeway to wire it as another type even though the type remains unchanged.


Anyway off to work now, see ya all later.

 

[GoldDigger]

My point was the building type classification remains the same we are just given leeway to wire it as another type even though the type remains unchanged.


Anyway off to work now, see ya all later.

Some room for confusion since Type (without any other qualifier) can mean too many different things. I thought you were saying that if the building permit was issued for a particular construction type (in the plans) then that would determine whether or not NM could be used.
We do agree.

 

[mgookin]

I disagree.

Building types are determined by the materials used, we don't get to call it something different.

As far as firewalls and dampers etc there may be exceptions for them just as we have for NM.

It's called Construction Type.

Construction type is not determined by the materials used. Construction type is determined by occupancy classification, height and area. Once you know your construction type, then you know what materials are allowed (or not allowed).

I don't see where an EC is qualified to make the determination as to what construction type is permitted. It's a building code issue and a building plans examiner is required to review it, not even the building inspector.

I'd also be interested to see what the handbook says about that article because many construe "permit" to mean "allow" when in fact in a building code, use of the word permit means "the building permit" or "the issuing of a building permit" and they're very careful about use of that term. As to what has been permitted, see the permit set of drawings; that's what's been permitted.

 

[mwm1752]

We used to wire 100,000 sq ft stores constructed out of steel and concrete with NM.

We could do that because the building codes would have allowed (permitted) these buildings to be constructed out of wood. The only reason metal and block was used was due to design reasons. So we were able to use NM.

We would probably still be doing that but the code changed and said we could no longer run NM above a suspended ceiling. That made it unpractical to continue using NM.

This must have been quite awhile ago -- & what about places of assemblies back then? Here is the 2009 IBC article ref.

602.2 Types I and II. Types I and II construction are those types of construction in which the building elements listed in Table 601 are of noncombustible materials, except as permitted in Section 603 and elsewhere in this code.
602.3 Type III. Type III construction is that type of construction in which the exterior walls are of noncombustible materials and the interior building elements are of any material permitted by this code. Fire-retardant-treated wood framing complying with Section 2303.2 shall be permitted within exterior wall assemblies of a 2-hour rating or less.
602.4 Type IV. Type IV construction (Heavy Timber, HT) is that type of construction in which the exterior walls are of noncombustible materials and the interior building elements are of solid or laminated wood without concealed spaces. The details of Type IV construction shall comply with the provisions of this section.
602.5 Type V. Type V construction is that type of construction in which the structural elements, exterior walls and interior walls are of any materials permitted by this code.

 

[iwire]

This must have been quite awhile ago -- & what about places of assemblies back then?

A supermarket is not a place of assembly.

We stopped using NM when the 2002 NEC took effect.

 

[mwm1752]

The supermarket in current IBC code is a group M (mercantile) -- It is interesting to read 518.1 commentary (I know not specific code) in NEC2011 how it relates to mercantile Use. "The assembly occupancies shall include but not limited to", as 518.2 states does raise a question to your statement of non assembly. The table seen in the NEC is in the IBC as code not commentary. What I am would be confident of is that plan review should have been specific for the inspector to allow NM wiring methods back them.

 

[eprice]

When the code changed regarding where romex could be used, I viewed this the way iwire and others have expressed it, but I have since changed my mind. I think it hinges upon what the word "permitted" means. I think a building is permitted to be built once a permit for that construction has been issued. And the type of construction of which it is permitted to be built is the type that is listed on the permit. The designer specifies the type of construction to be used and the AHJ approves that type of construction based on whether or not it fits within the code rules. There are times when a designer specifies type II-B construction for example, with an eye toward future flexibility even though type V-B would have been permitted had he specified that. Maybe the designer wants to preserve the possibility of a future addition to the building, or the possibility of a different type of future tenant.

If an electrical contractor takes it upon himself to say that the building could have been permitted to be V-B construction and wires it in romex, he is taking away the future flexibility that the designer intended to preserve. So, in my mind the type of construction of which a building is permitted to be built is the type that has been agreed upon by the designer and the AHJ, through the permitting process, and listed on the permit.

If the electrical contractor would like to save cost by wiring the building in romex, the proper course is to propose this to the designer. If the designer agrees, a change is proposed to the AHJ for a change in construction type. If the AHJ finds that the proposed change in construction type fits within the code rules, the AHJ would then change the the permit to allow the construction type to be V-B for example.

 

[GoldDigger]

When the code changed regarding where romex could be used, I viewed this the way iwire and others have expressed it, but I have since changed my mind. I think it hinges upon what the word "permitted" means. I think a building is permitted to be built once a permit for that construction has been issued.
If an electrical contractor takes it upon himself to say that the building could have been permitted to be V-B construction and wires it in romex, he is taking away the future flexibility that the designer intended to preserve. So, in my mind the type of construction of which a building is permitted to be built is the type that has been agreed upon by the designer and the AHJ, through the permitting process, and listed on the permit.

If the electrical contractor would like to save cost by wiring the building in romex, the proper course is to propose this to the designer. If the designer agrees, a change is proposed to the AHJ for a change in construction type. If the AHJ finds that the proposed change in construction type fits within the code rules, the AHJ would then change the the permit to allow the construction type to be V-B for example.

We will have to differ there, I guess.

1. mwm1752's quote above from the IBC makes no sense if the IBC is using the "strict" meaning of permitted as asserted. It shows clearly to me that in that quote permitted is synonymous with "allowed".

2. My take is that the NEC used the concept of what the construction was permitted (allowed) to be to avoid having to individually list tens or hundreds of different specific occupancies which might also have to vary depending on the building code in force at the jurisdiction.

3. There are literally hundreds of examples from the NEC that contradict the strict meaning of the word "permitted". Here are a few selections:

310.15(B)(7) (2011)

For individual dwelling units of one- family, two-family, and multifamily dwellings, conductors, as listed in Table 310.15(B), shall be permitted as 120/240-volt, 3-wire, single-phase service-entrance conductors, service-lateral conductors, and feeder conductors that serve as the main power feeder to each dwelling unit and are installed in raceway or cable with or without an equipment grounding conductor.

250.110(5) (2011):

Where supplied by a wiring method that provides an equipment grounding conductor, except as permitted by 250.86 Exception No. 2 for short sections of metal enclosures.

In the last one, I think that the detail described is one that will not appear in the building permit or associated plans, but will rather be determined by the AHJ at inspection.

The opinion that counts ultimately will be that of the AHJ.

 

[mwm1752]

The IBC determines the type of building 1 thru 5 in which what types of structural materials are used -- The A/B classification is determined thru the IBC includes fire resistance elements /use classification/stories & footprint. The process can be difficult to understand when determining all the factors. The building dept will be final say. the design of the building decides the permitted type of the structure. Certain building are not allowed to be wired in nm. Best alternative IMO is to use MC cable if you want to keep the romex style wiring method.