15-minute fire resistance rating for NM

[Christoph]

Hello

Inspector here. I failed someone for running Romex in a commercial building. Per 334.10(3) if they want to do that they will have to conceal that in the wall. They have EMT sleeved over it running up the walls (unfinished walls). They are asking if EMT can qualify as a 15 minute barrier. I said no as the code specifically mentions 15-minute rated assemblies such as walls, ceilings or floors. The "or raceways" remark is missing. Raceways also do not have a fire resistance rating associated to them as far as I know, only ratings for what assemblies they are allowed to penetrate.

My question is, would anyone be talked into letting them run Romex In EMT?

 

[rc/retired]

AFAIK there is no 15 minute rated assembly. I think it actually starts at 1 hour.
Anyway, I have approved NM cable in EMT, since there's a helluva lot of cable exposed out there.
Right or wrong on my part, I've never lost sleep over it.

Ron

 

[acrwc10]

have them fire caulk the end where the NM enters/exits and move on. there is no way the EMT is going to burn through. If you look at all the "fire wall penetration details" you will see EMT going through rated walls and getting sealed where they go through it.

 

[Christoph]

AFAIK there is no 15 minute rated assembly. I think it actually starts at 1 hour.
Anyway, I have approved NM cable in EMT, since there's a helluva lot of cable exposed out there.
Right or wrong on my part, I've never lost sleep over it.

Ron

1/2" drywall has a 30 minute rating.

 

[Christoph]

Talked it through with supervisor and some other Inspectors. This will still fail. 334.10(3) specifically talks about assemblies, not wiring methods. A raceway doesn't provide a fire resistance rating per IBC. Only assemblies such as walls do

 

[tortuga]

Does the EMT terminate on a metal box?

 

[wwhitney]

1/2" drywall has a 30 minute rating.

The tables in IBC Article 722 on calculated fire resistance rating provide for a 15-minute contribution from 1/2" gypsum board, or a 25-minute contribution if it is 1/2" Type X.

Cheers, Wayne

 

[wwhitney]

Talked it through with supervisor and some other Inspectors. This will still fail. 334.10(3) specifically talks about assemblies, not wiring methods. A raceway doesn't provide a fire resistance rating per IBC. Only assemblies such as walls do

If NM cable were listed in Table 310.4, or its inner conductors were labeled as one of types listed in the table, then I would say the installation is allowed if proper transition fittings (or boxes) are used at each end of the EMT. As then that portion of the installation is not relying on the permissions of Article 334 (NM Cable) but instead on the permissions of Article 358 (EMT). However, NM cable is not listed in Table 310.4, so that argument doesn't work--if article 334 were deleted from the NEC, we couldn't use NM cable inside EMT as a wiring method, it would violate Article 310.

Note that if this were SER cable, rather than NM cable, then 338.10(4)(a) would require compliance with Part II of Article 334, which includes 334.10, and so use of exposed SER cable in open framing in non-dwelling units would similarly be prohibited. But transitioning to EMT in the open framing would comply with the NEC, as the SER cable inners are labeled with one of the types listed in Table 310.4. I.e. even if Article 338 were deleted from the NEC, SER cable inside EMT would still comply with Articles 310 and 358.

So reluctantly, I agree with your conclusion. I don't think it's a rational outcome, however; I don't see how the thermoplastic jacket and conductor insulation of the NM cable is any more of a hazard inside the EMT that the thermoplastic jacket and insulation of other conductor types.

Cheers, Wayne

 

[Dennis Alwon]

What I was thinking was if emt is safe for thhn or similar conductors then why would nm be an issue inside a raceway.

This is assuming the building is classified for this type of wiring

 

[Christoph]

What I was thinking was if emt is safe for thhn or similar conductors then why would nm be an issue inside a raceway.

This is assuming the building is classified for this type of wiring

I came up with the paper contained in NM cable as a substantiation but that is merely speculation.

This brings up an interesting point for me as well:

IMO NM contained in EMT is still considered NM as a wiring method. Does anyone have any pointers?

 

[Christoph]

The tables in IBC Article 722 on calculated fire resistance rating provide for a 15-minute contribution from 1/2" gypsum board, or a 25-minute contribution if it is 1/2" Type X.

Cheers, Wayne

I appreciate this. I was looking for that before I broke down and did an internet search, where I came across some manufacturer of drywall stating a 30 minute rating. Thanks for the fact check!

 

[wwhitney]

IMO NM contained in EMT is still considered NM as a wiring method. Does anyone have any pointers?

I agree, only because neither NM nor its unlabeled inner conductors are listed in Table 310.4(A). For other cables installed in EMT, where the individual conductors are marked as one of the types in Table 310.4(A), may be considered EMT as the wiring method, whether or not the cable jacket is removed within the EMT. [If the EMT is just a sleeve rather than a conduit system with proper boxes or transition fittings at each end, then the jacket needs to stay intact, and it would still be considered the cable wiring method.]

Cheers, Wayne

 

[tortuga]

I would say if the NM enters a complete EMT run via a box or fitting then enters a panel, box or wireway, EMT is the wiring method enclosing a cable.
That is something I do often to bring NM into the bottom of a surface mount panel, otherwise for physical protection I'd have to comply with wierd sections like 312.5(C) and only enter the top of a surface mounted panel.

 

[Tulsa Electrician]

The way I read (3) it it can not be in any surface raceway
( exposed work).

(3) Other structures permitted to be of Types III, IV, and V construction. 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.

Basically no exposed walls etc.

Now build a wall around it and sheet rock it or some other approved wall covering. Than yes. Then no need for protection from physical damage and it is concealed.

I say ok for surface raceway containing NM in single and multifamily as mentioned in (1) and (2). I say no for any application of (3).

So my question is what type of construction was this installed within that the correction notice was issued.

Does it fall under 1,2 or 3 ?
If within 1 or 2, 3 does not apply.

Imagine the issues if was in an unfinished (studs and no rock)basement area of a house.

 

[acrwc10]

Hello

Inspector here. I failed someone for running Romex in a commercial building. Per 334.10(3) if they want to do that they will have to conceal that in the wall. They have EMT sleeved over it running up the walls (unfinished walls). They are asking if EMT can qualify as a 15 minute barrier. I said no as the code specifically mentions 15-minute rated assemblies such as walls, ceilings or floors. The "or raceways" remark is missing. Raceways also do not have a fire resistance rating associated to them as far as I know, only ratings for what assemblies they are allowed to penetrate.

My question is, would anyone be talked into letting them run Romex In EMT?

maybe I missed it but, I didn't see where you said where the EMT ended and what type of assembly it penetrated, if any. What type of construction is this, type V, lll, ll or type l ? in section714.5.2 exception 1 (of the IBC 2021) mentions "Membrane penetrations by steel, ferrous or copper conduits, pipes, tubes or vents". what type of "tube" do you think they are referring to if not EMT? also vents are normally thinner material than EMT, 26 gauge or less. After being called out to several structure fires, I can say with certainty, EMT will withstand a lot more fire than 5/8" type X drywall will. As an inspector it is not our job to pull the fly poop out of the pepper, it is to use our knowledge and experience to inspect a job, not just look for any reason to fail it.

 

[AC\DC]

Post 14 has it! what classification number of the building

 

[macmikeman]

This ^^^^^^^^^^^^^^^^^^^^^^^^^^

 

[macmikeman]

I have put nm cable in single story strip mall types of buildings before. However it all has been protected from physical damage by being conceiled in walls with drywall coverings. There are firewalls in those buildings between tenants and no way I would never run any nm thru one of the firewalls or party walls as it is commonly called, but I sure have run across other installs where just that is the case and found..............

Also - usually in every building that has lots of floors and needs elevators there is a whole lot of communications cables running thru the drop ceilings , lots of it unmanaged. I'd go after those installs way faster than I would finding NM inside emt in a building that allows nm wiring .........

 

[Christoph]

maybe I missed it but, I didn't see where you said where the EMT ended and what type of assembly it penetrated, if any. What type of construction is this, type V, lll, ll or type l ? in section714.5.2 exception 1 (of the IBC 2021) mentions "Membrane penetrations by steel, ferrous or copper conduits, pipes, tubes or vents". what type of "tube" do you think they are referring to if not EMT? also vents are normally thinner material than EMT, 26 gauge or less. After being called out to several structure fires, I can say with certainty, EMT will withstand a lot more fire than 5/8" type X drywall will. As an inspector it is not our job to pull the fly poop out of the pepper, it is to use our knowledge and experience to inspect a job, not just look for any reason to fail it.

The EMT ended up high with no transission fitting and NM was all exposed in the rafters.

As far as what type of construction it was I have to be honest here and say I did not even look at plans on this one. I usually do but I am still learning to be more secure and not get distracted by someone being overzealous or trying to put me on a leash during inspections.

Indeed the type of construction matters here. If one refers back to the uses permitted section of NM you will see that what is **permitted to be** of Types III, IV and V one is allowed to run NM concealed in the wall. As we established earlier, in these types of buildings we DO NOT run NM exposed, not in EMT or otherwise.

If we are looking further down in the section we find Types I and II addressed. Here one is allowed to run NM in any raceway that is allowed to be run in those types of construction. Exposed AND concealed.

Post 14 has it indeed. Like I mentioned before. **Walls and other assemblies** proved fire resistance rating. EMT does **not**. That is why this job was not approved and they are re-doing it. Type of construction os irrelevant here as NM will not be run exposed under any circumstances other than in a dwelling as outlined by 334.10.

 

[Christoph]

maybe I missed it but, I didn't see where you said where the EMT ended and what type of assembly it penetrated, if any. What type of construction is this, type V, lll, ll or type l ? in section714.5.2 exception 1 (of the IBC 2021) mentions "Membrane penetrations by steel, ferrous or copper conduits, pipes, tubes or vents". what type of "tube" do you think they are referring to if not EMT? also vents are normally thinner material than EMT, 26 gauge or less. After being called out to several structure fires, I can say with certainty, EMT will withstand a lot more fire than 5/8" type X drywall will. As an inspector it is not our job to pull the fly poop out of the pepper, it is to use our knowledge and experience to inspect a job, not just look for any reason to fail it.

I am not out to get people. I am the last person to want to cause people headach and more work. I am here to educate myself and make the right decision on the job, my inquiry here in this forum should be evidence for that. I understand the kind of inspector you are talking about and I agree. We need to understand and apply the intent of the code. Unfortunately, the NEC does not have the provision that the I-codes have where it specifically mentions that alternative materials and methods are acceptable to reach the same level of safety. The NEC provides us very cut and dry directions on how to build an electrical system.

As an immigrant to the US having grown up and completed my apprenticeship in Europe I am given to understand that half the reason inspectors exist in this country (they do not in Germany) is for the lawyers. And in this light I will not put a green sticker on something that is wrong, even though in the real world it would have been fine.

As far as the technical aspect is concerned I am not sure if you are on the right track. Your concern with penetrations and transitions from and to the EMT seems irrelevant for this case. As mentioned above there are considerations for penetrations but those relate to the assembly, not the wiring method. The only role that wiring methods would play for assemblies is their listing allowing or disallowing them to penetrate certain assemblies.

Thank you for your input on that. It is greatly appreciated