Outlet Boxes - Metal or Plastic?

[glenn bradley]

Won't we all be happy when Glenn finally finishes his sub panel and we can get back to talking wood?

My plan involves a few different outlet box locations:

Some will be in a wall, stucco exterior wall, wood studs, drywall interior to be added after electrical.

Some will be in a wall, stucco exterior, wood studs, OSB interior to be added after electrical.

Some will be in the "ceiling" mounted to wood joists, no exterior or interior wall.

So, plastic boxes or metal boxes or a mix?

[Matt Meiser]

In my shop, all the in-wall ones are plastic, mainly because they are so easy to use, no knockouts and cable clamps to deal with. Anything surface mounted is metal with 1/2" EMT running to it, except for my welder recptacle which needed larger conduit because of the size of the wire running to it (4-#10 if I remember correctly.) There I used plastic conduit/box because it was easier to work with.

[glenn bradley]

In my shop, all the in-wall ones are plastic, mainly because they are so easy to use, no knockouts and cable clamps to deal with. Anything surface mounted is metal with 1/2" EMT running to it, except for my welder recptacle which needed larger conduit because of the size of the wire running to it (4-#10 if I remember correctly.) There I used plastic conduit/box because it was easier to work with.

Thanks for the quick reply Matt. What are your interior walls made of if you have them?

[Jim O'Dell]

I used plastic exclusively in walls and ceiling. I have about 20 in the ceiling, and about 22 in the walls. Most all the wall receptacles are on the outside walls I think 4 may be on inside walls (it's only 14' long, and has a 6' door opening in it). I like plastic because it is non conductive. Just an extra measure of safety for me. :D Jim.

[Jeff Raymond]

Here's a quick tip having just built a new shop.

Use nylon face plates. They don't crack like the plastic ones.

Good luck!

[John Terefenko]

I like to use metal for just the oposite reason because they are conductive. Any shorts or grounds are in the box are known well before me. Just a matter of choice. Do you like Chevys or Fords???

[Stan Welborn]

All mine in the ceiling and walls are plastic. Never really thought about it.

[Gene Jordan]

Glenn,
I use metal boxes exclusively because of strength. If you ever have to change a switch or an outlet and have the screw strip out that enters the (plastic) box you will see what I mean. Almost every metal box that I've seen will have a tapped hole (sometimes on a raised boss) for a ground screw to make the metal enclosure safe from shock hazard. I always run the ground to the metal ground screw and then to the swith or outlet, in essence grounding both items together. At times the larger guage (usually 10 AWG or larger)wire is pretty stiff and if there is a kink in the conductor behind whatever you are entering into the box, you can be fairly confident that the screw will not strip at the slightest resistance when using a metal box.
Just my 2 cents worth.

[David G Baker]

I use both plastic and metal depending on the type of material the box is going to mounted in or on, the number of wires in the box and what I have on hand.

[Michael Lutz]

I would use metal. I have been replacing the original plastic ones in my house for two reasons: the screws strip out in the plastic boxes and the metal ones are sturdier than the plastic ones.

Mike

[Kent Fitzgerald]

I like the heavy duty plastic boxes (e.g., Carlon Super Blue). They have a lot of capacity (up to 22 cu in single gang), retain screws well, and if you did manage to strip a screw, there's enough beef to replace it with a larger size.

[Kent Fitzgerald]

Or metal cover plates. I found some nice Pass & Seymour stainless steel plates. While I'm no interior designer, I think the gray devices and SS plates have a pretty cool industrial look.

[Mike Emde]

I have found the plastic boxes to be more user friendly, bringing cable into the box and mounting is easier. Just remember when putting any boxes on your outside walls that you use insulated boxes and vapour barrier boxes. You can buy a sleeve the goes over box that tapes onto your vapour barrier keeps the draft out.
i remember working on our last home and replacing a damaged plugin and it was a steel box. Depending what kindof boxes you use some are clamped together well this one came apart in the wall needless to say it was an interesting project

Best of luck
Mike Emde

[Matt Meiser]

What are your interior walls made of if you have them?

7/16" OSB, painted white.

[Greg Crawford]

Again it's the Chevy or Ford thing. I like metal for strength (I also use the SS plates for durability), but they are more work. I try to screw them to framing members with drywall screws so they don't move around like plastic boxes will. Remember, a metal box is required to be grounded so the breaker will trip to prevent a person from being shocked if they touch a metal box that is in contact with a live wire. The grounding pigtails can be a real pain.

[Bernhard Lampert]

For my house and my shop, I used metal for the same reasons that were mentioned before: stronger box, attached stronger to the wall, more versatile, stronger taps for adding the fixture. An occassional wayward swing with a hammer during construction will destroy a plastic box, but the metal box will survive. Also noticed that the pastic boxes deform easily when nailed to tight. Cutting out metal boxes in drywall and other paneling using a Rotozip is a breeze, but with plastic boxes you are likely to cut the box or start melting it where the guide touches the box.
Just don't get any of the so-called handy boxes, use 4x4 boxes with the appropriate mudring: Plenty of space for the wiring with little chance of a cable fill violation.
Metal boxes may be a bit more expensive and a bit more work, but IMHO, they are a superior product.

my 2 cents,

Cheers,
Bernhard

[glenn bradley]

Thanks to all for the replies. I plan to do as Matt described with the 7/16" OSB across a large portion of wall. This will have two quad boxes in it. It doesn't sound like plastic boxes are a fire concern without the drywall(?). Right?

I'll go metal with all the exposed boxes. As stated, it really easier and cheaper than doing them again, if damaged.

[Sean Troy]

7/16" OSB, painted white.

Matt, what type of primer and paint did you use? Any bleed through? thanks, Sean

[Rod Sheridan]

Hi Glenn, plastic boxes may be convenient however;

1) what is the box lifespan? Metal boxes are almost unlimited, yet I've seen some 10 year old plastic boxes that are beginning to develop small cracks

2) Metal boxes are stronger, and fireproof, plastic while fire retardant, aren't fireproof. Something to consider if there's an arc in the box.

3) non metallic enclosures require bonding of armour or metal conduit with grounding bushings, not common in houses however a consideration for shops.

I don't use any plastic boxes, and prohibit them from projects at work.............Regards, Rod.

[Matt Meiser]

Matt, what type of primer and paint did you use? Any bleed through? thanks, Sean

I don't remember what it was--just a regular primer from Lowes. Since I was priming 30x32x12' worth of walls I needed a lot and just bought something inexpensive in a 5 gal pail. When I was done priming it looked aweful. However the paint (again, something inepensive in a 5 gal pail) covered really well after priming. Yes, there was some minor bleed through, but it is a shop, not a museum. Overall it looks really good.

[Eric Gustafson]

My vote for metal. For all the reasons stated above, plus they have a rock solid feel when you plug an appliance into them.

[Bill Wyko]

Ditto! When you push a plug into a plastic box it feels like it's going to go through the wall. I'm all for metal.

[Ben Grunow]

You may not be roto zipping out the holes in drywall but pro drywall crews use the zipper and roitinely ruin the screw holes on plastic boxes.

They are junk invented by someone looking to charge slightly less for a far inferior product. Sorry for the anger but as a builder I am constantly removing these things (mostly from low voltage subs work) and replacing them with metal. They wont listen and I wont have em.

Metal, Metal, metal. The cost is only a couple hundred more for a whole house.

[glenn bradley]

As always guys, thanks for the input. I am not talking about more than 10 boxes so for the small price difference (in the grand scheme of things) I may just go all metal.

[Mike Emde]

I have used KILZ and have found it to be the best, especially when priming anything for outdoor painting.
I used it on a triple layer facia board made out of cedar. It was awsesome no bleeding at all and cedar is terrible for that especially on outdoors.
KILZ comes in a can with red letters and white can

[David G Baker]

Matt, what type of primer and paint did you use? Any bleed through? thanks, Sean
Sean,
I use PVA, a Sheetrock primer, it seems to work fine. I use high gloss white for the finish coat, it does a good job of hiding the OSB look and helps bounce the light around as well brighten things up a little.

[Bas Pluim]

It depends on the location. I had some surface mounted boxes in a basement that had started to rust after 10 years. Replaced them with rugged plastic. In a wall cavity, rust wouldn't be an issue.

Plastic is cheaper. Metal is stronger. Plastic installs easier, metal is easier for maintenance.

Flip a coin :-)

Bas.