5 Mistakes DIYers make using metal electrical boxes

Don't make these mistakes with metal electrical boxes
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If you are starting to do electrical work in your home you will likely run into a metal electrical box either because it is what was originally installed or your area typically uses metal boxes instead of the plastic boxes you see in many DIY electrical videos. Here are 5 mistakes you want to avoid making when using metal electrical boxes.

0:00 Introduction
1:09 Mistake 1
2:22 Mistake 2
3:53 Mistake 3
4:25 Mistake 4
5:49 Mistake 5
6:40 Wrapup

The information provided in this video is for informational purposes only. Usage of any information in this video is done at your own risk and the host and producer accept no liability. You should consult the local building code and requirements in your area and abide by all regulations when taking on any project in your home. Consult a licensed professional if you feel uncomfortable with any of the information in this video.

Many links are affiliate links where you pay the same amount and the seller compensates me a small amount for doing the work to recommend only those tools and products I trust.

[James_Knott]

I learned how to properly use a metal box, I have never used a plastic box, in my high school electricity class. We did house wiring in grade 11, back in the late 60s. Back then, we used Marr connectors, instead of Wago, to join wires. One mistake I saw, in our own home, was in the receptacle near the kitchen sink. When the house was built, in the mid 50s, grounded outlets were only required near the kitchen sink and laundry tub. The "electrician", who wired that outlet, instead of extending the ground wire from the box to the outlet, used a nail under the outlet ground screw and touching the metal box!!!. By the time I saw that, many years later, the tip of the nail had rusted away, leaving the outlet ground terminal ungrounded!

[Sparky-wwre]

Nice video many folks would find useful since metal boxes in new residential construction are not nearly as commonplace as they were many years ago. Nonetheless there are certain applications around the house where plastic boxes are unacceptable, and we need to understand the differences in order to make safe electrical installations. As a side note, although not required, I like to wrap the switch or receptacle with a few layers of electrical tape before installing it in a metal box, especially in multi-gang switch boxes containing dimmers with screws instead of wire leads. You'll thank yourself for taking this extra step after a few times blowing up a $30 dimmer.

[f.robertfalbo]

Most older steel boxes didn't have those grounding screws and required a green grounding clip to be installed. It might be nice if you addressed that problem with older steel boxes.

[brucepayan]

6:39. The existing ground wire is on the wrong side of the screw. Swap it to the right side and put the pigtail on the left.

[cecillec]

Thank you very much for the very clear explanations.

[steveurbach]

When using Wago/wire nuts, I prefer that the Source romex ground wire be the one under the screw. The box stays grounded in case of other fails

[TheShaggyfrog]

I was wondering why the switches in my 1978 house didn't have ground wires connected to them, rather only to the metal box. I now know from a little tid bit where you mentioned it. Thanks.

[channelI]

We use a flat cable in the UK very similar with a ground/earth cable with no sheathing we call it Twin and Earth but we don't leave the bare copper cable exposed we add a sheath.

[richardbrobeck]

those are some great tips I see too many times that the wires are cut way to short !

[iMergeAndSee]

I would add one edit to your list for DIY'ers using Metal boxes when Romex and other non class wires.
Even when secured, the sharp edges of most boxes can cut into wire making the box live. Add bushings to protect your unclad wires be they Romex, Solid, Stranded Etc. Most DIY'ers think the bushings are for water proofing. I see it everyday.

[J.C...]

The last house I moved out of was built in the 50s. Most plugs weren't grounded properly and 95% of them had live and neutral swapped because whoever renovated the house obviously wasn't an electrician. So, they put every receptacle in wrong.

Being a guitar player, it wreaked havoc on my tube amp. The noise was terrible.

Thank God I moved into a newer house that was built in the late 80s. When I plugged my amp and guitar up and turned them on, it was so quiet I thought maybe the power didn't turn on lol.

[craigt]

Hi-
Thanks for the video. I have one question. In the video you connected the ground wire and a separate pigtail ground to the ground screw; then connected both to a Wago connector. My question is why did you need the pigtail ground if the incoming ground wire is already connected to the ground screw? Also could you have just pigtailed from the ground screw to the Wago, and then connected all other incoming ground wires to the Wago? Thanks!

[danlux]

The older bx wires had no ground wire but an aluminum grounding strip that is difficult to secure to the box.

[brucesail]

I installed a big, chunky GFCI outlet in a metal box. The outlet body was so large that it caused the hot screw to short out to the grounded box. I turned off the breaker after it popped and insulated the screws with electrical tape and also inserted a plastic tab between the outlet and the box as insulation. Never had that happen with light switches or standard outlets, but now I always use tape and an insulator tab whenever I install metal boxes.

[tomherd]

Why is there a Ground and Neutral wire. The neutral wire is grounded in the main box so it seems one would work. Is it a load issue or possibly an open/broken wire issue, or extra safety issue??

[InverhavonRailways]

In the UK, the earth (grounding) wire has to be sleeved, and most accessories have recessed line and neutral terminals to prevent shorting. Don't know why it's never been adopted in the US.

[craigbrummert]

Thanks for the video. Very helpful. In the last situation with a short ground and adding a dimmer switch, can I use a straight through wago connector and screw only the long ground from the dimmer switch under the box screw?

[nyetloki]

NEC 2020 says that the ground connection in the box should not be used for any other purpose. So you cant screw the ground conductor to the box AND use it for the device. A pigtail/second wire must be used.

[paulmoffat]

I have noticed in the last few years (USA), metal boxes no longer come with 'included' grounding screws, but you MUST purchase them separately ! How cheep are those manufacturers getting!

[DavidBerquist]

I have seen conduit used as the ground and self grounding receptacle used will it pass inspection