plastic electrical boxes

[stryped]

Can plastic electrical boxes be used inside a detached gasage with no interrior walls?

[Les]

Stryped, (aka Stryped)

Your asking if plastic boxes can be used, for whatever, along the inside surface of the exterior walls? ceiling fixtures? fans? etc..

[stryped]

Just outlet boxes and wall switches. Where there is no interior wall. Just wall studs. "Like a workshop detached building"

[gregzoll]

Actually, the wire should be twisted together, just hanging from the stud with excess to catch stuff on. Of course, the Plastic boxes can be used. What do you think is supposed to be used to tie in wires for switches & outlets? Some people prefer Metal JBs, but Plastic is so much cheaper & less hardware to install.

[Jeff Remas]

Yes, they(plastic boxes) can be installed in open, unfinished framing. Carlon, a manufacturer specifically states that this is allowed.

[Jim Katen]

Yes, they(plastic boxes) can be installed in open, unfinished framing. Carlon, a manufacturer specifically states that this is allowed.

The plastic boxes aren't the problem. This is not a dwelling. It's a detached garage or shop. He should have used UF or MC, not NM.

- Jim Katen, Oregon

[Brandon Whitmore]

The plastic boxes aren't the problem. This is not a dwelling. It's a detached garage or shop. He should have used UF or MC, not NM.

Will you provide me with a code cite so I can read into this further....

[Jim Katen]

The plastic boxes aren't the problem. This is not a dwelling. It's a detached garage or shop. He should have used UF or MC, not NM.

Will you provide me with a code cite so I can read into this further....

Look at 334.10, especially (3)

[Jeff Remas]

Yup, Install all the boxes you want but just don't hook up any wiring to it.

I use 334.10(3) to cite NM used for a garbage disposal under a sink. Or I cite subject to physical damage 334.15(B). Unfortunately 334.15 sort of contradicts 334.10(3). I think this is a poorly written section.

Maybe we should debate the use of NM in an unfinished basement where 10/2 NM is used to feed down to the top of a water heater where the last staple in above the water heater on a joist 42" above the connection.

[Jim Katen]

Yup, Install all the boxes you want but just don't hook up any wiring to it.

I use 334.10(3) to cite NM used for a garbage disposal under a sink. Or I cite subject to physical damage 334.15(B). Unfortunately 334.15 sort of contradicts 334.10(3). I think this is a poorly written section.

Ah, but if you consider that 334.10(3) only applies to structures other than one- and two-familiy dwellings, it makes more sense. I'd stick to 334.15(A) & (B) for disposals & water heaters.

Maybe we should debate the use of NM in an unfinished basement where 10/2 NM is used to feed down to the top of a water heater where the last staple in above the water heater on a joist 42" above the connection.

Clearly a violation. But easy enough to remedy with some conduit or with a cleverly constructed 2x4 batten.

- Jim Katen, Oregon

[stryped]

The plastic boxes aren't the problem. This is not a dwelling. It's a detached garage or shop. He should have used UF or MC, not NM.

Will you provide me with a code cite so I can read into this further....

What is UF or MC that I shopuld have used? So if I leave no interror walls on my garage are the plastic boxes ok or not?

[Jeff Remas]

Plastic boxes cannot be used with MC. Not designed for that application.

If you are not going to get the job inspected by the local electrical inspector then don't worry about it. No one will ever know until something goes wrong.

[Jim Port]

Jeff,

On what basis would you site 334.10(3) on a disposal? This is not another structure.

334.10(3) deals with other types of buildings like a detached garage that are not mentioned in (1) and (2).

I would also like the hear your thoughts on all the physical damage that occurs under the kitchen cabinet.

334.10(3) would apply regardless of 334.15 if the other structure was not a dwelling. If used in another type of structure you need the 15 minute finish to cover the cable.

[Jim Katen]

. . . What is UF or MC that I shopuld have used? So if I leave no interror walls on my garage are the plastic boxes ok or not?

Stryped,

NM is the kind of cable you used. (It stands for nonmetallic-sheathed cable.) Most people refer to it by the brand name Romex. NM cable has a lot of restrictions on its use. Most of them are governed by article 334 of the NEC. Among these restrictions is the requirement that NM cable be used only in dry locations. A detached shop or garage is a damp place, the NM cables there will be subject to condensation. If you're going to use NM cable in a detached garage, you're supposed to cover it with a "thermal barrier of material that has at least a 15-minute finish rating. . ." Your installation has other problems with lack of support for the cables and lack of protection in places.

If you had hired an electrician, he probably would have used UF cable (underground feeder cable), which can be used in damp & wet locations. UF cable looks similar to NM cable, but it has much stouter insulation around it. Like NM cable, it has to be protected from physical damage, but it doesn't have to be covered up that way that NM does in an outbuilding.

Alternatively, your hypothetical electrician might have used MC cable (metal-clad) for a very nice installation - but MC doesn't work with plastic boxes.

- Jim Katen, Oregon

[Brandon Whitmore]

Look at 334.10, especially (3)

Thanks Jim.

I wouldn't have considered an enclosed shop or garage a damp place, so it's back to study time for me...

When did this first become a requirement? Only reason I ask is almost all of the detached structures I see have NM/ NM-B installed.

[Bain]

Look at 334.10, especially (3)

Thanks Jim.

I wouldn't have considered an enclosed shop or garage a damp place, so it's back to study time for me...

When did this first become a requirement? Only reason I ask is almost all of the detached structures I see have NM/ NM-B installed.

Same here. I have exposed cable in my own detached garage.

The local code yokels around here don't seem to mind it much, either.

[kurt]

I'm not very knowledgeable on nylon jacketed wiring materials, but I don't recall ever seeing UF cable in an unfinished garage.

Does anyone ever see UF cable in garages?

[AHI in AR]

NM cable is the rule around here in detached garages also. Then again, they are generally outside areas where there's any muni inspections. Honestly, I didn't know it was wrong. Ironically, the few UF installations I remember were typically found in cases where there were enough other problems that they were obviously done by someone other than an electrician.

Damn. I learned something else today despite my efforts not to.[]

[Chad Fabry]

Hmmm, if nm isn't allowed in garages then it really isn't allowed in basements.

That'd make, uh let me do the math... carry the two, carry the one..uhh let's see... that makes 99.9999% (give or take one ten thousandth of a percent) of all homes in the northeast non-compliant.

I don't have my NEC at home... how is "damp" defined?

[Jim Port]

From Article 100

Location, damp. Locations protected from weather and not subject to satuaration 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.

Location, dry. A location not normally subject to dampness or wetness. A location classified as dry may be temporarily subject to dampness or wetness, as in the case of a building under construction.

At least in my experience the inside of a building above ground would not be considered damp.

[kurt]

Honestly, I didn't know it was wrong.

Neither did I.

After reading Port's cite, I don't think it's a damp location, and I don't think it's wrong.

Is there some other restriction other than dampness? (besides exposure to damage and that sort of stuff...)

[Jim Katen]

Honestly, I didn't know it was wrong.

Neither did I.

After reading Port's cite, I don't think it's a damp location, and I don't think it's wrong.

Is there some other restriction other than dampness? (besides exposure to damage and that sort of stuff...)

The restriction has to do with the fact that the garage is detached.

334.10 (3) says that, if you're going to install NM cable in a structure that isn't a dwelling, then the "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 . . . ."

This change was introduced in the '02 edition.

- Jim Katen, Oregon

[Brandon Whitmore]

Jim,

Do you find local AHJ's enforcing this?

Do you write this up fairly often?

What materials would be considered to have a 15 minute finish rating?

Thanks for all of the answers as usual.

[Jim Katen]

Jim,

Do you find local AHJ's enforcing this?

Hard to say. I can't remember the last time I inspected a post 2002, non-dwelling structure that lacked interior finishes and that was actually built under a permit.

Do you write this up fairly often?

I probably would if I saw it often.

What materials would be considered to have a 15 minute finish rating?

I know 1/2" drywall does. Don't know about others.

[Speedy Petey]

Even though you don't consider this a "dwelling structure", it still falls under the electrical codes for "dwelling units".

For reference, just look at 210.8 of the NEC, the requirements for GFI protection.

Here is the section in exact text. Garages and accessory buildings fall under the "Dwelling units" category.

(A) Dwelling Units. All 125-volt, single-phase, 15- and 20-ampere receptacles installed in the locations specified in (1) through ( shall have ground-fault circuit-interrupter protection for personnel.

(2) Garages, and also accessory buildings that have a floor located at or below grade level not intended as habitable rooms and limited to storage areas, work areas, and areas of similar use

So in the eyes of the NEC a residential garage or accessory building to a dwelling is still a dwelling structure.