Metal Boxes in Residential???

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Fulthrotl

~Autocorrect is My Worst Enema.~
up until 2-3 years ago, i'd never worked with a plastic box or a wirenut on a joint in residential.


the company i apprenticed for used steel boxes and we soldered all connections. i did the same when i went out on my own.

up until recently many contractors here were still using steel boxes in resi; most have switched to plastic, but still solder their connections.

i went to the dark side of plastic and wirenuts after a few lashings on this forum for my midieval ways. it wasn't as bad as i thought it would be, and i was able to still sleep at night, so i figured what the hell. its cheaper.

operating in the semi dark ages, i use 4sd boxes ...
everything fits without being placed with a hammer handle,
gfci's and dimmers fit quite nicely, thank you.

bathrooms and kitchens, i use steel boxes... plastic is ok everywhere
else, outside boxes get steel, so i have room for the gfci.

now, yes... they cost more.... and i 'splain to the customer, that they
are getting a $5 box in the wall, instead of a 35 cent box, and why
that is beneficial to them.

like for example, when you have the boxes in the kitchen behind granite,
and the homeowner didn't bother to freshen up the electrical when they
spent $60,000 on a solid cherry kitchen remodel, and the box is floating
in the wall, and its a single gang that was done in the 60's before gfi's,
and the device won't fit in the box, and you can't get to it cause that
pretty granite, and pretty cherry is installed....
 

muskrat

Member
Location
St. Louis, MO
operating in the semi dark ages, i use 4sd boxes ...
everything fits without being placed with a hammer handle,
gfci's and dimmers fit quite nicely, thank you.

bathrooms and kitchens, i use steel boxes... plastic is ok everywhere
else, outside boxes get steel, so i have room for the gfci.

now, yes... they cost more.... and i 'splain to the customer, that they
are getting a $5 box in the wall, instead of a 35 cent box, and why
that is beneficial to them.

like for example, when you have the boxes in the kitchen behind granite,
and the homeowner didn't bother to freshen up the electrical when they
spent $60,000 on a solid cherry kitchen remodel, and the box is floating
in the wall, and its a single gang that was done in the 60's before gfi's,
and the device won't fit in the box, and you can't get to it cause that
pretty granite, and pretty cherry is installed....

TYPICAL !! $60K for cherry and granite but couldn't swing the extra $$$ for an EC to upgrade/properly install the ele.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I had a customer complain because he wanted metal plates everywhere because he did't want plastic in his house. I laughed and said you should have said something earlier because all the wiring is plastic and the boxes, and the receptacles you plug into. But, I added, I would be happy to install stainless plates. :grin: We did...
 

growler

Senior Member
Location
Atlanta,GA
I had a customer (via the contractor) ask why we didn't use metal boxes in their bathroom remodel.


I would ask them why they think you should use metal boxes. Just point out that plastic is fully "code compliant" and that 99.9999 percent of new construction for residential is plastic boxes. Anything other that what is considered standard trade practice would have to be specified in the plans or contract.

Tell them that it is possible to use metal boxes but there is no good reason to do so and that it will add to the cost of the job. Most of the time "added cost" will do the trick. :)
 

220/221

Senior Member
Location
AZ
I know that he might say that the box would be grounded therefore trip the breaker if something "hot" gets against it......


What would happen if something "hot" gets against a plastic box? Nothing?


Some uninformed people thing that plastic anything is cheap and metal anything is better. Non metallic were designed to use with non metallic cable. It seems common sense. Explain to them that, with NM wiring systems, a non conductive junction box is better/safer.

Granted, this was a hacked installation but there would not have been a fire if it was a plastic box.

.
electrical170.jpg
 

brantmacga

Señor Member
Location
Georgia
Occupation
Former Child
. . .. .
As for plastic verses metal, I just tell the home owner what it would have cost if the job was done with metal box's and explain how much more problems can be caused with metal box's, especially those little JEM box's, and how allot of devices like GFCI's and some dimmers won't fit into them, (well they will if you hammer the wires back) using 1900s would be even more money, and like others said, with plastic, less problems with the screws shorting on the sides of the box's, which if you wire like me, I pig tail and use the screws, which leaves them sticking out just a bit. the other thing is the clamps, how many times have you found a short at a clamp? I'll bet never with a plastic box.

most that hear this don't have a problem.

i never had a problem getting devices into a metal box. use the appropriate size and everything works fine. a shallow plastic box is just a painful as a shallow metal box.


we did have the problem with clamps; to clarify, I did not have a problem with clamps, but some impatient helpers did. not many problems with shorts, but more with AFCI's tripping.

I really don't care either way; I haven't done any new residential that wasn't for a family member in over two years, but i'll use whatever they want to pay for. If its competitive bid i would certainly figure using plastic.
 

readydave8

re member
Location
Clarkesville, Georgia
Occupation
electrician
I have also heard that metal boxes are better for dimmers because they dissapate heat. I have not seen any evidence presented to prove or disprove so it may not be true.
 

tryinghard

Senior Member
Location
California
I haven't read the whole post, so please forgive if I?ve jumped in too late. I'm just gona say the plastic are rated correctly, cheaper, and more efficient. In my opinion metal boxes are a waste of money and they do not provide a better job with nonmetallic cabling nor do they make it safer.
 

brantmacga

Señor Member
Location
Georgia
Occupation
Former Child
the one really nice thing i can think of about using metal boxes, is that when the drywall crew covered our boxes, we used a big magnet to find their exact location.

except that one time they covered 30. and i used a sledgehammer to find them. no one dared send me a chargeback for it.

no need to paint markings on the floor.
 

norcal

Senior Member
Plastic boxes are a reliable & proven method, but I still like 4 square boxes (1900 boxes to you Easterners) & rings over NM boxes.
 

dieselram752

Member
Location
mass
I like to use deep metal new work boxes for 3+ gang switch boxes.
It just seems more solid with a bracket screwed to a stud on each side even if i need to add a stud.
Takes some extra time but seems worth it.
The box stays level till the finish.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
It just seems more solid with a bracket screwed to a stud on each side even if i need to add a stud.
Takes some extra time but seems worth it. The box stays level till the finish.
The multi-gang boxes I've seen have a tab, sometimes with nail/screw holes, on the end opposite the nails. If you're going to add a stud anyway, it works for plastic, too.

Added: The tab is supposed to keep the box from moving outward, while the device straps are supposed to keep it from moving back. Level depends on how you re-shape the box after nailing, and the drywaller's work ethics.

I remember when multi-gang boxes came with a telescopic-ish bracket for the next stud. That was back when the high leg on a hi-leg Delta was 190v instead of 208v. ;)
 
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Chamuit

Grumpy Old Man
Location
Texas
Occupation
Electrician
I can't find a pic right now, but, I've seen a two-sided nail-on box that's 4.5" deep and takes devices on both sides.

I've seen those around here (rarely) on older homes. I thought they weren't made anymore because of fire ratings.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
...
Plastic is inherently SAFER. There is no way for wires to energize the box, then the yoke, then the little screws on your switchplate which, if the ground wire malfunctioned, would carry 120V and shock you. Because metal boxes are "likely to become energized" electricians have to spend extra time to ground them to protect the final user.
I see very little difference...a fault to the yoke will still energize the face plate screws assuming the same faulty EGC. You still only need to make one EGC to something. With the metal box the connection is to the box itself and with a plastic box the connection is to the device. I don't see any time difference.

Plastic boxes have more space inside for air flow and cooling of wires which results in a more efficient system.
That is a function of box volume. You can get the same volume in a metal box.

Because plastic boxes are larger inside and "breathe" better, the expensive devices like GFI outlets and dimmer switches install easier and last longer.
Again a function of the box size that you use.

Metal boxes still have their place, but in my expert opinion plastic is the better way to go most of the time.
And mine is that I just don't like plastic boxes.
 

brantmacga

Señor Member
Location
Georgia
Occupation
Former Child
Even if you have over 200 outlets and controls in a residence and you do over 25 of these a year? :-?

when i was a wee apprentice, we did about 75 homes per year, w/ over 100 outlets each, and all metal boxes w/ soldered joints.


nothing to it once you get the hang of it, except the cost.
 
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