Use of nm cable in dwelling garage

[Raccoon 3]

Is it permitted to use nm cable in a residential garage exposed.

 

[TOOL_5150]

Is it permitted to use nm cable in a residential garage exposed.

in CA, you can get away with it exposed if its over 8' [even though its not in the code book] but as far as in the walls, if you arent finishing them - use MC

~Matt

 

[erickench]

I would say a garage is considered to be a damp location. The cable would have to be type NMC. This type of cable has a corrosion resistant jacket suitable for both exposed and concealed work in dry, moist, damp, or corrosive locations.

 

[kbsparky]

Why would a garage be considered to be a damp location? The main purpose of having a garage would be a nice dry place to park your vehicle? :-?

 

[480sparky]

I would say a garage is considered to be a damp location. ............

I've never heard of this interpretation, unless the garage is more like a carport.

 

[erickench]

Then answer me this. Why are GFCI receptacles required in a garage? As I read the code I get the impression that GFCI receptacles are required in places that are wet, damp or where there is water close by i.e. sink, etc. One would think that a garage has moisture and that's why a GFCI is required.

 

[crazyboy]

Then answer me this. Why are GFCI receptacles required in a garage? As I read the code I get the impression that GFCI receptacles are required in places that are wet, damp or where there is water close by i.e. sink, etc. One would think that a garage has moisture and that's why a GFCI is required.

I would think GFCI's are required more because the garage would typically have tools plugged in, and people usually plug outdoor items into the receptacles in the garage. GFCI's are required in basements also, are you saying that you don't run nm in the basement?

 

[erickench]

are you saying that you don't run nm in the basement?

I'm not saying that. There are three different types of NM cable that the NEC allows to be used in dwellings. Basements are damp locations. I just noticed that GFCIs seem to be required in locations that are wet or damp. But since you brought it up I personally would not use Type NM cable for anything except temporary lighting unless it is concealed inside the masonry or concrete of a building. I don't like it exposed.

 

[radiopet]

Firstly, I am not sure this is the right area for this type of question but alas it is here so here is my comments.

334.10 Uses Permitted. Type NM, Type NMC, and Type
NMS cables shall be permitted to be used in the following:
(1) One- and two-family dwellings.
(2) Multifamily dwellings permitted to be of Types III, IV,
and V construction except as prohibited in 334.12.
(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.

You have other issues as to the NM Cable within the garage ( should we assume you are speaking of a detached garage?) I would tend to think of the following concerns:


334.15(B) Protection from Physical Damage. Cable shall be
protected from physical damage where necessary by rigid
metal conduit, intermediate metal conduit, electrical metallic
tubing, Schedule 80 PVC conduit, or other approved
means. Where passing through a floor, the cable shall be
enclosed in rigid metal conduit, intermediate metal conduit,
electrical metallic tubing, Schedule 80 PVC conduit, or
other approved means extending at least 150 mm (6 in.)
above the floor.
Type NMC cable installed in shallow chases or grooves
in masonry, concrete, or adobe, shall be protected in accordance
with the requirements in 300.4(E) and covered with
plaster, adobe, or similar finish.

So a strong argument that in a garage exposed, the NM Cable would be subject to physical damage due to the general nature of a garage. ( atleast in mine anyway ). Many will say that the detached garage is part of the dwelling unit itself but I would disagree and say it would fall under the guidelines of 334.10(3)

BTW....the madate for GFCI's in garages is because the NEC says to install them in the garage and their is no link to a wet location in that requirement regarding garages and I would not call them a wet location or a damp location for that matter.

My opinion is that NM Cable would be allowed in the detached garage as long as you meet the requirements in 334.10(3) and 334.15(B).

 

[C3PO]

I'm not saying that. There are three different types of NM cable that the NEC allows to be used in dwellings. Basements are damp locations. I just noticed that GFCIs seem to be required in locations that are wet or damp. But since you brought it up I personally would not use Type NM cable for anything except temporary lighting unless it is concealed inside the masonry or concrete of a building. I don't like it exposed.

Most basemants are not damp locations. I have never even seen NMC before every wire manufaturer I have talked to about it say it does not exist

 

[kbsparky]

NMC is basically the same thing as type UF.

 

[erickench]

According to Mike Holts book "Understanding the NEC" basements, barns and cold storage warehouses are considered to be damp locations. Wherever there's a chance that water or moisture might seep in because of bad drainage, a faucet inside a garage, etc. A garage or basement might have water on the floor for these reasons.

 

[radiopet]

According to Mike Holts book "Understanding the NEC" basements, barns and cold storage warehouses are considered to be damp locations. Wherever there's a chance that water or moisture might seep in. A garage or basement might have water on the floor.

But not all basements are considered a damp location. Mike may make this statement simply because the NEC also makes that statement in the definition:

Location, Damp. Locations protected from weather and
not subject to saturation with water or other liquids but
subject to moderate degrees of moisture. Examples of such
locations include partially protected locations under canopies,
marquees, roofed open porches, and like locations,
and interior locations subject to moderate degrees of moisture,
such as some basements, some barns, and some cold storage
warehouses.

This simply can't be a broad assumption, this is why the electrical inspector has to interpret onsite the issues. I have a basement that has never had any moisture within it and I have a detached garage that has never had any signs of moisture within it. Lets remember the question is being posed about Garages and this is not a listed location in Mike Holts statement and they use such as to give examples not mandates.

 

[Minuteman]

Then answer me this. Why are GFCI receptacles required in a garage? As I read the code I get the impression that GFCI receptacles are required in places that are wet, damp or where there is water close by i.e. sink, etc. One would think that a garage has moisture and that's why a GFCI is required.

Because of the concrete floor. It's all about the potential.

 

[BAHTAH]

NM Cable in garage

NM Cable in garage

A garage is not a dwelling. 334.10 does allow NM cable in type V buildings which I would consider a typical frame built garage, attached or not. 334.10(3) requires a 15min finish rating of the material covering the ceiling or walls. 334.15 (B) requires where necessary that NM cable be protected from physical damage by some type of conduit or "other approved means" which I take to mean the 15min finish covering of the walls and ceiling. I know in our area the AHJ requires the cable to be run in the walls and the walls to be covered. If the walls are not going to be covered we run EMT.

 

[norcal]

When the GFCI requirement for garages was first introduced, I had read that the reasoning was people were likely to plug in outdoor power equipment into garage receptacles.

 

[iwire]

Firstly, I am not sure this is the right area for this type of question but alas it is here so here is my comments.

334.10 Uses Permitted. Type NM, Type NMC, and Type
NMS cables shall be permitted to be used in the following:
(1) One- and two-family dwellings.
(2) Multifamily dwellings permitted to be of Types III, IV,
and V construction except as prohibited in 334.12.
(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.

I agree with Paul here, this recent change prohibits using NM exposed in detached garages.

You have other issues as to the NM Cable within the garage ( should we assume you are speaking of a detached garage?) I would tend to think of the following concerns:


334.15(B) Protection from Physical Damage.

In my opinion we should forget the Physical Damage issue as that is a judgment call made by each area. Some areas traditionally allow NM in these location some areas do not.

The 15 min barrier requirement is not a judgment call it is clearly required and tends to make the damage issue moot anyway. :smile:

 

[Dennis Alwon]

Does this mean nm cable cannot be sleeved in a raceway or does a raceway have a fire rating? Even so by this statement it appears nm would not be allowed

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.

 

[charlie]

NMC is basically the same thing as type UF.

As far as I know, NMC is no longer manufactured and UF us an acceptable substitute for NMC. Actually, since UF is permitted to be used in place of NM or NMC, electricians didn't use NMC. Then, since it was seldom used and it was an extra item to be stocked NMC was not manufactured any more.

 

[hillbilly]

Because of the concrete floor. It's all about the potential.

That's exactly what I was thinking too.

steve