Metal Outlet Boxes Yay or Nay?

[checkthisout]

Is it smart or even within code to use metal outlet boxes?

I want to use them in my workbench area and outside on the same plug-ins that will utilize commercial quality outlets because I think the outlet will be less likely to pull out over time.

Good bad?

Thanks in advance.

 

[walrus]

Metal boxes are fine, you just need to bond them.

 

[tfi racing]

I just finished up a rough in on a major house reno using plastic boxes.I never have used them before,but thought I would give them a try because that is what the majority of the locals use.I just don't like them and will try not to use them again,at least now I have justification for my long standing bias against plastic boxes.

 

[rinny_tin_tin]

Is it smart or even within code to use metal outlet boxes?

I want to use them in my workbench area and outside on the same plug-ins that will utilize commercial quality outlets because I think the outlet will be less likely to pull out over time.

Good bad?

Thanks in advance.

We did this recently when I asked a similar question regarding preferences of plastic v metal. My experience has always been metal - however, I couldn't make an argument over the PVC boxes. In any case - if its listed - metal or plastic - its fine.

 

[Uncle Buck]

If you have code concerns, the big thing about metal boxes is to permanently mount them and not use them at the end of extension cords, and at the end of suspended pendant drops. Those are violations of NEC, and in the workplace, are violations of OSHA codes.

 

[mrb]

If you have code concerns, the big thing about metal boxes is to permanently mount them and not use them at the end of extension cords, and at the end of suspended pendant drops. Those are violations of NEC, and in the workplace, are violations of OSHA codes.

yep. Have to use a proper pendant box like these:

 

[Uncle Buck]

yep. Have to use a proper pendant box like these:

CORRECTAMUNDO! and those babies are high, north of $40 if I am not mistaken.

 

[mrb]

CORRECTAMUNDO! and those babies are high, north of $40 if I am not mistaken.

I think I usually sell them in the mid $30s so yeah...

I have been looking into getting them made. The mold is alot of $$$, and UL isnt cheap either.....

 

[checkthisout]

We did this recently when I asked a similar question regarding preferences of plastic v metal. My experience has always been metal - however, I couldn't make an argument over the PVC boxes. In any case - if its listed - metal or plastic - its fine.

Nice Avator and thank you.

It looks like I just have to be sure the box itself is grounded.

Rough-ins around here always use plastic and of course there are two grades of plastic boxes etc.

My main concern was durability with the tight-fitting commercial quality outlets and the corresponding amount of force it takes to pull a cord out might wear-out a plastic box over time.

I will be going with metal!

 

[Falcon67]

FWIW - I used plastic in the shop because they were all on the side of a stud. I also use them in the house, 98% are old work boxes in there. Never had one fail, break, come lose, etc. Several in the shop get big heavy cords yanked out and plugged in a lot. If I run anything that will be exposed or out in the open along the wall in the shop I prefer to use metal. I have been known to pull the nails out of new work plastic and replace them with 3" deck screws. Metal is good stuff - I will typically strip a bunch of 14ga to make 6"ish ground pigtails for the boxes.

Here's a good question - is it OK for the bare pigtail to be under a box mounting screw or should it terminate at it's own bonding screw in the box?

 

[rinny_tin_tin]

Nice Avator and thank you.

It looks like I just have to be sure the box itself is grounded.

Rough-ins around here always use plastic and of course there are two grades of plastic boxes etc.

My main concern was durability with the tight-fitting commercial quality outlets and the corresponding amount of force it takes to pull a cord out might wear-out a plastic box over time.

I will be going with metal!

Thank you and your welcome. I was a bit leery at first of the outlet-holding threading of the blue plastic boxes - where there is no thread, and the screw cuts one as it is driven in. They hold pretty tight! One thing I don't like about the blue plastic boxes are the strain reliefs - they use these plastic springy uni-directional thingys that are supposed to allow the cable to go in, but not allow it to go out. They don't work so well. I think in our last go around on this subject the consensus was that for industrial applications, metal is the best way to go and precisely for the reason you identify - frequent plug in/plug out, etc!

 

[Falcon67]

One thing I don't like about the blue plastic boxes are the strain reliefs - they use these plastic springy uni-directional thingys that are supposed to allow the cable to go in, but not allow it to go out. They don't work so well.

I fix those - cut 'em off with a pair of dikes.

 

[rinny_tin_tin]

I fix those - cut 'em off with a pair of dikes.

Hahahah....but then what do you use?...or use nothing at all?

 

[mrb]

FWIW - I used plastic in the shop because they were all on the side of a stud. I also use them in the house, 98% are old work boxes in there. Never had one fail, break, come lose, etc. Several in the shop get big heavy cords yanked out and plugged in a lot. If I run anything that will be exposed or out in the open along the wall in the shop I prefer to use metal. I have been known to pull the nails out of new work plastic and replace them with 3" deck screws. Metal is good stuff - I will typically strip a bunch of 14ga to make 6"ish ground pigtails for the boxes.

Here's a good question - is it OK for the bare pigtail to be under a box mounting screw or should it terminate at it's own bonding screw in the box?

the ground has to be sized for the circuit, so you cant use 14ga pigtails on a 20a circuit. You cant put the ground pigtail under a box mounting screw. It has to be under a grounding screw threaded into the box. Has to be a machine screw, cant use a self tapping sheetmetal screw.

 

[malibu101]

the ground has to be sized for the circuit, so you cant use 14ga pigtails on a 20a circuit. You cant put the ground pigtail under a box mounting screw. It has to be under a grounding screw threaded into the box. Has to be a machine screw, cant use a self tapping sheetmetal screw.

Where I do much work the screw must also be green!
I once used "regular" machine screws through the threaded hole because I was out of ground screws and got shot down for it.
I think that was because the AHJ had nothing else to scrutinize on the job.

 

[rinny_tin_tin]

FWIW - I used plastic in the shop because they were all on the side of a stud. I also use them in the house, 98% are old work boxes in there. Never had one fail, break, come lose, etc. Several in the shop get big heavy cords yanked out and plugged in a lot. If I run anything that will be exposed or out in the open along the wall in the shop I prefer to use metal. I have been known to pull the nails out of new work plastic and replace them with 3" deck screws. Metal is good stuff - I will typically strip a bunch of 14ga to make 6"ish ground pigtails for the boxes.

Here's a good question - is it OK for the bare pigtail to be under a box mounting screw or should it terminate at it's own bonding screw in the box?

"Here's a good question - is it OK for the bare pigtail to be under a box mounting screw or should it terminate at it's own bonding screw in the box?"

When UL tests the boxes for listing, the item is tested using the grounding screw. Aside from the UL protocol, I think the concern would be if the mounting screw came loose (say it was buried in a wood stud that weakened) making for a less than effective ground bond - possibly permitting an arc fault. Although electrically, termination of the grounding conductor at any place on metal box is nodally identical to the grounding screw, the nature of the mechanical connection may be compromised.

 

[malibu101]

"Here's a good question - is it OK for the bare pigtail to be under a box mounting screw or should it terminate at it's own bonding screw in the box?"

When UL tests the boxes for listing, the item is tested using the grounding screw. Aside from the UL protocol, I think the concern would be if the mounting screw came loose (say it was buried in a wood stud that weakened) making for a less than effective ground bond - possibly permitting an arc fault. Although electrically, termination of the grounding conductor at any place on metal box is nodally identical to the grounding screw, the nature of the mechanical connection may be compromised.

I think you summed it up. UL tested it this 1 way and approved it that way.
Any other way is not approved.
That does not mean the UL way is the only adequte way, just the only recognized way.

 

[malibu101]

2008 NEC 250.148 (C)
METAL BOXES- A connection shall be made between the one or more equipment grounding conductors and a metal box by means of a grounding screw that shall be used for no other purpose, equipment listed for grounding, or a listed grounding device.

 

[Joe92GT]

I fix those - cut 'em off with a pair of dikes.

That violates code unless you then staple the wire with in 8 inches of the box if I recall.

 

[hidollartoys]

Is it smart or even within code to use metal outlet boxes?

I want to use them in my workbench area and outside on the same plug-ins that will utilize commercial quality outlets because I think the outlet will be less likely to pull out over time.

Good bad?

Thanks in advance.

AGAIN Back to the original question..........Depends on application and location. For fixed locations(stud mounted or secured) behind wall coverings both are fine but there my be limitations in your code area(city,county,etc).

As for which is better....this is a matter of personal preference. I personally have never seen a "properly installed" box of either type pulled out of the wall. And if a receptical has been pulled from a plastic box is was done in the event of some stupid situation that would have also rendered a metal box inoperative until repairs were done. If unough force is exerted on a box/recept. that the box exits the wall then maybe you should evaluate your plug/unplug procedure. I have plastic boxes in my shop and have not had any failures.

my .02

 

[Falcon67]

That violates code unless you then staple the wire with in 8 inches of the box if I recall.

That's what I do, beats those plastic chinese handcuffs in the box.

I usually use a threaded screw on a metal box, sometimes hard to find. Don't recall seeing green ones - have to look on the isle at HD or Lowes. Oops on the 14 ga, my bad stating a generality vs the specific circuit requirement. I just put in some lights, all with 14 ga wire so I must be in 14 gauge mode.

I would add that if I had a do over - I would put in either junction boxes where a wire turns south down a wall to a plug run - OR - run conduit and boxes on the wall surface. It's a PITA to add a plug when the boxes are buried in the wall and the wall is full of batt insulation. And - put in quad outlets.

 

[checkthisout]

AGAIN Back to the original question..........Depends on application and location. For fixed locations(stud mounted or secured) behind wall coverings both are fine but there my be limitations in your code area(city,county,etc).

As for which is better....this is a matter of personal preference. I personally have never seen a "properly installed" box of either type pulled out of the wall. And if a receptical has been pulled from a plastic box is was done in the event of some stupid situation that would have also rendered a metal box inoperative until repairs were done. If unough force is exerted on a box/recept. that the box exits the wall then maybe you should evaluate your plug/unplug procedure. I have plastic boxes in my shop and have not had any failures.

my .02

I have never seen a box damaged either except for the "el-cheapo" very thin 48 cent a piece boxes.

Metal just sounds and feels better to me in a shop-type application with the commercial type outlets.

And isn't that what we all want? Just to feel good while we are plugging and unplugging things from our outlets?

 

[mrb]

That's what I do, beats those plastic chinese handcuffs in the box.

I usually use a threaded screw on a metal box, sometimes hard to find. Don't recall seeing green ones - have to look on the isle at HD or Lowes. Oops on the 14 ga, my bad stating a generality vs the specific circuit requirement. I just put in some lights, all with 14 ga wire so I must be in 14 gauge mode.

I would add that if I had a do over - I would put in either junction boxes where a wire turns south down a wall to a plug run - OR - run conduit and boxes on the wall surface. It's a PITA to add a plug when the boxes are buried in the wall and the wall is full of batt insulation. And - put in quad outlets.

when you say box buried in wall, do you mean entire box and cover behind the drywall?

 

[thdewey]

Great NOW I have to replace the metal outlet box on my extention cord....

It is always pluged into a GFCI outlet and is bonded. Oh well, safety first.

 

[Falcon67]

when you say box buried in wall, do you mean entire box and cover behind the drywall?

No, just standard depth - wall plate on the surface. But the shop uses 1/4 OSB on the walls not sheet rock and they are filled with insulation so it's a real pain to get in there to thread anything new.

 

[Phuckin' Jim]

AFAIK, Metal boxes are the ONLY ones allowed to be used around here.....

 

[Coach James]

I hate plastic boxes. The boxes in our building are all plastic and I think half of them have the holes where outlets and switches attach stripped out. I've been replacing most of the outlets in the building and the one problem I have over and over are the stripped out holes.

Coach

 

[boiler7904]

Metal boxes and conduit are required by code in my area for new construction or remodel work subject to inspection.

Fiberglass boxes are generally more durable than plastic - especially when nailing them up. You always seem to miss at least one and have little bits of blue plastic flying everywhere.

 

[rwhite692]

I have plastic boxes for all of the 110V outlets in my shop...Never had a problem with them.

Had to use the metal ones with 3/4" round hole knockouts for the 220V outlets for welder etc, where 6-3 wire was used (in order to be able to use the cable clamps, to secure the wire where it enters the box)

 

[Diablo]

Im a metal box guy, the one exception is in a corrosive or wet location. The way it was explained to me was the metal box is there to contain the fire first and foremost.

 

[v7guy]

I've been running the plastic ones in the garage and house, the 220 is getting the metal ones because, as mentioned, it's the only way to run 6/3 (that I could find).

I've not had any problem with the plastic boxes, but that's just me. your results may vary