Metal Vs Plastic Electrical Boxes | Avoid This Common DIY Mistake

Do you feel comfortable using metal electrical boxes on your DIY electrical projects around the house? If not, you are like the majority of my audience who indicated they prefer to use plastic boxes. There are a lot of advantages to metal boxes but you do need to have some knowledge to ensure you aren't making common DIY mistakes.

Free Home Maintenance Checklist:

DISCLAIMER: This video and description contain affiliate links, which means that if you click on one of the product links, I’ll receive a small commission.

[d.e.b.b]

As a child, my dad always made me watch him working around the house, so, as he put it, I would know how to fix things when I grew up. Dad was a custodian in a public school; had something called a black seal fireman's certification, and had learned all sorts of electrical, plumbing, and construction skills from the 'real' professionals during his lifetime, because he watched them, when they came to work on the systems at his school. It makes me so happy, to know that he really did know what he was doing, and how important it was to him, to make sure that I learned how to do things the right way. I watch your videos, and remember my dad, teaching me how to do so many things correctly and up to code, even though he wasn't a professional electrician. So I thank you, and I thank my dad, for the knowledge that you both pass along to me, so I won't burn my house down.

[GeekWireless]

What I do with metal boxes is make the pigtails to 7" to allow me to wrap the bare ground wire around the green screw in the box; then, rest of the bare wire is attached to the ground screw to the outlet ground screw.
That way you do not need the additional green pigtail and the Wago splice

[ReverendTed]

A light fixture in our entryway nearly fell out of our ceiling because the blue plastic junction box was basically crumbling. The house was built in 2009, so it was only 14 years old. Definitely went with a metal box to replace it.

[jimmeade]

For grounding the box, a common thing I've seen in homes is to wrap the Romex's ground wire around the ground screw and then connect it to the outlet. Fewer wires makes for more space in the box, which is helpful on single-outlet metal boxes.

[ramosel]

As a young man fresh out of the cockpit of a Navy Fighter Jet, I had the opportunity to put my education to work on a "Dark Project". I was mainly building test and data acquisition systems. But, sometimes we had to run power and that was child's play comparatively. But, I had to take a 3 week crash course in "absolute code" from a NEMA Engineer. For work in our environment, pigtails were NOT permitted on any electrical devices, nor could we use "insecure" plastic boxes . We had to leave at least 18" of hangout when applying the strain relief to the incoming wire. Once the jacket was removed from any romex, this then left you with an 16-17" long bare ground wire. This ground wire would be wrapped around the ground screw in the metal box (further providing strain relief for the cable) then given enough loop to work with, attached to the ground lug of the (first) receptacle and trimmed accordingly. If you had a 2nd receptacle in the box you could wrap the first receptacle ground lug and continue to the 2nd receptacle's ground lug. So you end up with a contiguous ground from supply cabinet to device, no connections to go sour. I went on to bigger and bolder things before I retired... but when I do work at my own home, this is still how I wire everything. It's a "what if" you can eliminate.

[Rocksinhed]

I've been and Electrician for over 40 years. Nice information. I use ALL metal boxes ALL the time. I am retired now in Arizona and do mostly old work with romex, as such the old work metal box comes with Romex clamps already installed. The main reason I learned to use metal boxes is NYC Code. The code was written in case the outlet catches fire the spark or fire would be contained. I tape EVERY OUTLET just in case and bare conductor has a chance of hitting a screw ect and so the next guy doesnt get zapped.
Loved your information... and as per NYC Code .. you take the ground conductor and wrap it around the ground screw in the box and as one continuous wire go to the ground on the outlet
Have a great day and keep up the good work

[erics]

My dad built the house I grew up in back in 1957 and all the boxes were metal and the wiring was BX. So, when I did retrofits, I learned to work with both effectively. I do like the added strength of metal boxes.

[ScienceOfThePS]

Keep in mind that some jurisdictions require metal boxes and EMT per local code, such as Chicago and the surrounding area. Always check with your municipality on what they allow!

[realfloridaredneck]

I'm a commercial electrician, since I usually use metal boxes, I'd prefer the metal over plastic. They make push in plastic bushings for romex that is a bit easier for the DIYer to install their romex into the boxes; that would save them the effort of fiddling around with locknuts. I really like that you used the 2 1/8" deep box over the 1 1/2" boxes, if I can get away with using deep boxes like that, I always do. Quick tip for DIYers, if you don't want to mess with pigtails, rather than pulling more ground wire out of the romex, which shrinks the ground on the other side of the wire, give yourself enough space to attach that ground to both the box and the device. Typically when doing a rough-in, I like to give myself about 18" of wire at each box, yes there's a little waste at the end, but wire can always be cut to length and it gives enough ground wire for me to tie that ground onto the ground screw and make that bond, rather than cutting separate pigtails. I'm also a big fan of "fold as you go" so you're not fighting to install that device, it's not a big issue with the box you've got and a single device that you're installing, but if there's a possibility of adding another device in the future or the box is smaller, it's always a good habit to leave yourself extra space in the box, it also looks much neater and it will allown that device to go in straight.

Either way, good video.

[kliajesal]

I'm an aspiring electrician. I've done a little electrical work re-wiring outlets, changing their location, etc. but metal boxes have always concerned me specifically for the reason of them becoming energized. The information here about pro-grade outlets and switches having a lead to the ground built into the tabs is very illuminating and the rest of this video de-mystified things that I didn't understand before. Thank you!

[YardworkWithJohn]

When I first started doing work in my house, I liked plastic. They were cheap and easy. But as time goes on, I hate plastic more and more. SO much flexing, most installed with nails that can back out. It just feels like a hackey solution. But getting a metal box, screw it in properly and it's rock solid, not going anywhere ever. It's more expensive and it takes more work to install but the end result is better for me.

[AlanTheBeast]

I may be mistaken but I believe Canadian code does not allow using a separate wire to bond the metal box as you show.
Instead the ground coming into the box must go to the box ground first and then continue to the outlet ground. So when bringing the cable into the box you plan on the ground wire hitting the ground screw first. If you plan this it works out elegantly most of the time.
You "can" depend on the screw carrying the ground from the box to the outlet, but I prefer to have a solid connection.
If you do a "workman" like job, you don't need to tape over the terminals.

[kpdvw]

what a convoluted way to ground a metal box! Just loop the bare ground wire from the Romex cable around the bonding screw and be done with it! No Wagu connectors/wirenuts needed!

[allenshepard]

Great video. Lots of detail and love the comparison. Yes, I've forgotten to remove the clamp ring.
1) The grounding screw for the grounding conductor has to be green in color in America . Other screws fit but one can fail an inspection.
2) Yes, the yoke tabs will provide a mechanical ground. Work on some old homes were the connections are loose or corroded. The electrical ground, using a wire to wire connection is better. There is less electrical noise (long explanation about dissimilar metals and their effects.) and lower resistance for tripping breakers. Tripping breakers during a bad event is what we want.
3) DIYers forget there is a two conductor limit for many small clamps. Check the package for use.

[NipkowDisk]

I use metal boxes almost exclusively. The one exception I made was when installing a pair of duplex outlets between my garage door openings on the inside; there was a gap such that the heavy-duty plastic box bridged it easily with the mounting ears.

[ericpelto]

I have been a DIY for over 58 years and have learned many things over the years. Things have been added to my toolbox and a lot more thrown out. Like in this video, I added the WAGO connectors many years ago, but my friends just can't get rid of their wire nuts. And the one major thing I really liked were the star screws used to attach the metal box to the studs. I threw out Phillips screws years and years ago. But my son in law still has buckets of phillips screws and stripped out bits because his father won't try out those fancy square screws. I started using square headed screws in clock building in my teens and have not gone back to phillips screws since the 1980's. I hope younger DIY'ers caught the screws used to attach that metal box. That will save thousands of hours of wasted time looking for that phillips screw that shot out of your screwdriver. But remember big box stores are not hip to them fancy screws and you will have to buy online to fill your toolbox or screw sorted utility cabinets

[deanrhodenizer]

When I use metal boxes, I strip the Romex a bit longer. Then I wrap the bare wire around the grounding screw before connecting it to the outlet. When I have two pieces of Romex in the box I either setup up a pigtail arrangement, if not I wrap the longer bare wires around the grounding screws (2) and then twist them tightly together for about an inch and a half and snip one off before connecting it to the ground terminal on the outlet.

[Alabamaweldinginspector]

I have built a Quonset hut for my shop and used all metal boxes and metal conduit with a ground wire . Everything is grounded properly so I am comfortable with the metal.

[patrickmorris]

I am a commercial electrician, t
Metal boxes are all I have ever used including in residential. I used a ground wire pig tail with a green screw in ever box. Ever Metal box is grounded to the ground wire in the MC 12-2 or romex 12-2. Never had a problem. Always passed rough in inspection.

[workshop]

When fishing into a metal box knockout you can use a plastic bashing which can be installed from inside the box. The bushings typical have retention ears built in to keep the wire from pulling out.