NM vs MC vs EMT/Rigid... When and where it's permissible to use, and WHY?

[mwm1752]

your engineer used code references that would apply to type of construction --
(A) Types NM, NMC, and NMS. Types NM, NMC, and NMS cables shall not be permitted as follows:
(1) In any dwelling or structure not specifically permitted in 334.10(1), (2), (3), and (5)
334.10 Uses Permitted
Type NM, Type NMC, and Type NMS cables shall be permitted to be used in t he following, except as prohibited in 334.12:
(1)One- and two-family dwellings and their attached or detached garages, and their storage buildings. Not Applicable to situation
(2) Multi-family dwellings permitted to be of Types III, IV, and V construction. Not Applicable to situation
(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. Only applies to specific area’s not type of construction
(5) Types I and II construction where installed within raceways permitted to be installed in Types I and II construction. Still can use NM in a raceway.
Certianly sounds confusing -- were the code sections the engineer stated recieved by the building dept plan review? Do not know about CEC

 

[EEEC]

your engineer used code references that would apply to type of construction --
(A) Types NM, NMC, and NMS. Types NM, NMC, and NMS cables shall not be permitted as follows:
(1) In any dwelling or structure not specifically permitted in 334.10(1), (2), (3), and (5)
334.10 Uses Permitted
Type NM, Type NMC, and Type NMS cables shall be permitted to be used in t he following, except as prohibited in 334.12:
(1)One- and two-family dwellings and their attached or detached garages, and their storage buildings. Not Applicable to situation
(2) Multi-family dwellings permitted to be of Types III, IV, and V construction. Not Applicable to situation
(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. Only applies to specific area’s not type of construction
(5) Types I and II construction where installed within raceways permitted to be installed in Types I and II construction. Still can use NM in a raceway.
Certianly sounds confusing -- were the code sections the engineer stated recieved by the building dept plan review? Do not know about CEC

The CEC reads word for word it this particular instance.

I actually stated the code sections to the engineer to justify changing his note in the approved set of drawings. He then replied in agreement stating that he would send a letter of amendment as instructed by the city's Building Division Administrative Analyst I ("counter person"). This is just the first step. I still need to verify with the AHJ, namely the "senior inspector", before beginning installation. My main purpose for creating all this hassle is an attempt to save my customers (friends) about $30K for what I feel is an unnecessary requirement (based on my interpretation of the code).

 

[jap]

The CEC reads word for word it this particular instance.

I actually stated the code sections to the engineer to justify changing his note in the approved set of drawings. He then replied in agreement stating that he would send a letter of amendment as instructed by the city's Building Division Administrative Analyst I ("counter person"). This is just the first step. I still need to verify with the AHJ, namely the "senior inspector", before beginning installation. My main purpose for creating all this hassle is an attempt to save my customers (friends) about $30K for what I feel is an unnecessary requirement (based on my interpretation of the code).

Good luck with that.

JAP>

 

[EEEC]

Good luck with that.

JAP>

Please expand on your comment.

 

[jap]

It's just that anytime you hear "Retail Office Space" in our area, we're prone to consider it a commercial establishment from the start, and bid it as such.

Not saying that yours is, but, had I of quoted a project like this and not been for sure, I would have been sure to note on my proposasl that all wiring was figured to be installed in NMB and any other wiring method would be at an additional cost and covered myself.

If the owners (Your Friends) spent the money to have the project professionally engineered and the notes on their print indicate EMT,MC and excludes Romex (which is very common by the way) theres the chance that your going around them, could relieve the engineers and architects of their design responsibility, seeing as how they may have other reasons for suggesting the more durable wiring method.

Around here, it's not uncommon for even MC Cable to be refused on engineered projects (except for fixture whips) much less romex.
But,
Nothing of what I said above may even relate to your circumstance.

JAP>

 

[EEEC]

I would have been sure to note on my proposasl that all wiring was figured to be installed in NMB and any other wiring method would be at an additional cost and covered myself.

I did

If the owners (Your Friends) spent the money to have the project professionally engineered and the notes on their print indicate EMT,MC and excludes Romex (which is very common by the way) theres the chance that your going around them, could relieve the engineers and architects of their design responsibility, seeing as how they may have other reasons for suggesting the more durable wiring method.

I've got a stamped amendment in my possession allowing NM-B on this project, direct from the engineer who designed the electrical drawings. Now my only hurdle is getting the city (AHJ) to corroborate.

 

[david]

I did



I've got a stamped amendment in my possession allowing NM-B on this project, direct from the engineer who designed the electrical drawings. Now my only hurdle is getting the city (AHJ) to corroborate.

Note at least in this area getting NM cable approved as a wiring method in types III, IV and V construction. Does not address the uses not permitted for exposed installations above suspended ceilings, exposed in basement floor joist and in attic (truss) spaces where access to these spaces is provided.

The use of NM as a wiring method here must be concealed in spaces, or must be concealed... It has been excepted to box in NM cable in suspended ceiling spaces and in attic spaces satisfying the requirement of concealment in 15 min construction. In other words providing physical protection for wiring that otherwise would have been exposed.

 

[EEEC]

Note at least in this area getting NM cable approved as a wiring method in types III, IV and V construction. Does not address the uses not permitted for exposed installations above suspended ceilings, exposed in basement floor joist and in attic (truss) spaces where access to these spaces is provided.

The use of NM as a wiring method here must be concealed in spaces, or must be concealed... It has been excepted to box in NM cable in suspended ceiling spaces and in attic spaces satisfying the requirement of concealment in 15 min construction. In other words providing physical protection for wiring that otherwise would have been exposed.

Okay, excellent! Just as someone pointed out to me earlier, the building type IS located on the cover sheet of the plan set; it is a type V. It is a slab floor and the TI is located on the first floor of a two story building. No suspended ceiling. ALL BASES COVERED! Thanks for helping me clarify david!

 

[jap]

Let us know how it works out.

Jap>

 

[EEEC]

Let us know how it works out.

Jap>

Thank you everyone for your input.

 

[mwm1752]

So it appears the original change was directed by the private engineer & not the building dept -- :jawdrop: