plastic or metal junction boxes

**Master Brian** · 01-07-2009, 10:29 AM

Out of curiousity, what is the main difference besided the material. Why do some prefer metal and others prefer plastic. Is there any safety issues or is it just a matter of personal preferance?? My understanding is the metal ones need to be grounded.

**220/221** · 01-07-2009, 11:41 AM

Plastic boxes are far superior for NM cable wiring simply because the don't conduct electricity.

Plus they are less expensive and easier to install.

Some people think plastic = cheap.

**jamiedolan** · 01-07-2009, 01:58 PM

Originally Posted by Master Brian

Out of curiousity, what is the main difference besided the material. Why do some prefer metal and others prefer plastic. Is there any safety issues or is it just a matter of personal preferance?? My understanding is the metal ones need to be grounded.

Most plastic boxes are not rated for exposed work, i.e. concrete walls in the basement. So metal is much easier to use there.

I've had some bad luck with some styles of plastic boxes cracking and breaking when installing them. I am sure some of the plastic boxes are better than others, I would suggest getting the better quality plastic boxes if that is the direction your going.

Jamie

**codeone** · 01-07-2009, 02:01 PM

Originally Posted by Master Brian

Out of curiousity, what is the main difference besided the material.* Why do some prefer metal and others prefer plastic.* Is there any safety issues or is it just a matter of personal preferance??* My understanding is the metal ones need to be grounded.

Yes the metal ones do have to be bonded. (grounded)

**frenchie** · 01-07-2009, 04:26 PM

The threaded holes for the screw that hold the device, strip out way more easily on plastic boxes.

**220/221** · 01-07-2009, 05:07 PM

I have never seen or stripped a screw hole on a Carlon blue box.

I have seen some old grey Slater quick clip boxes circa 1980 where the little metal tabs broke completely out and I had to replace about a dozen of them. The Carlon boxes have a hole thru about 3/8" of pliable plastic. You can run drywall screws in ond out of them with ease if you need longer screws. They can't strip because they are not threaded.

**codeone** · 01-07-2009, 07:16 PM

Originally Posted by frenchie

The threaded holes for the screw that hold the device, strip out way more easily on plastic boxes.

What size drill/driver are you using to run the screws in and at what torque setting to do this?

Have seen this complaint quite often. Suggest you use one of the smaller compact drill/drivers with th torqu setting just enough to bottom out the screws.

**WV Hillbilly** · 01-08-2009, 09:08 AM

I have seen light fixture boxes used for & called junction boxes . If installing a box in a ceiling that might have a light fixture or ceiling fan hung on it I always use a metal box . If the box is to be used for a junction box only , either should be fine .

**jamiedolan** · 01-08-2009, 11:22 AM

Originally Posted by WV Hillbilly

I have seen light fixture boxes used for & called junction boxes . If installing a box in a ceiling that might have a light fixture or ceiling fan hung on it I always use a metal box . If the box is to be used for a junction box only , either should be fine .

If a plastic box is UL listed as a fixture / junction box, then it is fine to use for either.

Use the correct box where necessary and it is all legal, metal or plastic.

Jamie
*I am pretty sure there are some schd 80 plastic rated for exposed work, but am not positive, I use metal.

**WV Hillbilly** · 01-08-2009, 04:52 PM

I didn't say it wasn't legal to hang a fan or heavy light fixture on a plastic box . I just prefer a metal box for those applications .

hj · 01-09-2009, 08:35 AM

quote; Some people think plastic = cheap

So you must be one of the three or four people who do not think that. Would you REALLY hang a fan on a plastic box, unless the mounting bolts were fastened to the structure and not the box?

**220/221** · 01-09-2009, 03:59 PM

So you must be one of the three or four people who do not think that

.

Yeah. Me and the other three guys made the decision to install platic boxes in 98% of the houses built since 1980.

Would you REALLY hang a fan on a plastic box, unless the mounting bolts were fastened to the structure and not the box?

Hey, I wasn't the one who changed this to a fan box thread. Try to keep up plumber.

**codeone** · 01-09-2009, 04:04 PM

is it UL listed for it. If it does it would pass for the weight rating of the box!

**Scuba_Dave** · 01-09-2009, 05:17 PM

I installed one of the heavier duty plastic fan boxes with support in my sunroom. I still didn't like the feel, support
So I ran a 2x4 between the rafters & screwed the box to that
It doesn't budge at all now

I like the deeper plastic boxes - more room
The existing metal boxes in this house were way too small
My basement still has a few larger octagon metal boxes
I installed plastic boxes at the ceiling level or on partition walls
Unfinished basement, I didn't want any boxes down low
We are near a stream & possibility of flooding if heavy rain & the sump pump failed