2 Most Common Issues DIYers Make With Metal Electrical Boxes

Metal electrical boxes have many advantages over their plastic counterparts but there are a few things that are classically done incorrectly. I will walk you through 2 of the most common examples I see in houses around my area. And then more importantly how to correct or avoid these 2 issues.

Parts Used

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Chapters
0:00 Intro
1:08 Most Common Example When I Use Metal Boxes
1:47 1st Example of Incorrect Metal Box Install
2:54 Example in Early 1900's Home
3:48 How To Correct the 1st Issue
6:10 2nd Example of Incorrect Metal Box Install
8:09 How To Correct the 2nd Issue
10:00 Wrap Up

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[danielquaternik]

Just wanted to tell you how much I appreciate all of your videos. I'm a DIY'er and attend University of Youtube all the time. Your videos are extremely helpful and you present them with absolutely no arrogance. A lot of people are much too quick to jump into the comments to pound their chests that you are wrong and they know it all. I encourage all these "pros" to take the time and share their wealth of knowledge to us DIYers and make videos to teach us all. Again, Thank you and keep up the good work.

[tomhouseknecht]

I have recently watched a couple of your videos, as an electrician for 45 years, thank you for taking the time to hopefully prevent someone from hurting themselves or others. Box fill, stapling, proper access are other items I run across over time. Education is good.

[toddwrenn]

I do property maintenance, but I do a lot more than what a typical handyman would do. I know enough, to not do things I shouldn’t be doing. I really enjoy learning new things, and I always learn something new watching your videos. Thanks for putting these out there.

[ADBBuild]

I've never understood the hate for plastic boxes. I've never seen one fail, but I have seen SEVERAL old rusty metal boxes, or metal boxes without clamps being used, or screws corroded into them, or wires shorting against the inside, etc. With plastic, there is no risk of the box being electrified if something goes wrong. Sure, they will melt in a fire, but if it gets to that point, a melted box is the least of your worries. Not to mention the ease of installing old work boxes without needing to screw them to a stud.

[wildpat]

There is a 3rd advantage for the clamps at the knock-off hole in the side of metal boxes: It prevents pests to enter the box. A mouse can squeeze in very easily and create a short inside.

[peteheckman]

Thanks so much! I just did BOTH of these on a project in my attic adding a couple of lamp holders. I came looking because I felt like the Romex in the sharp knock-out was not code.. now I know what to go get! I had completely forgotten about the ground for the box; my lamp holder does not have an outlet so I assumed there was no need. Luckily I can just go ground the box with my stuffed ground wire. Awesome videos!

[kyscott]

I've read a lot of people making something simple as grounding a metal box into a major issue. My grandfather who was a master electrician and maintenance engineer showed me years ago the simplest and cheapest method of box grounding.
When you bring your "line" wire into the box be sure to feed an extra couple inches in length. Add your ground screw and when you separate your wires from the insulation press the ground wire down and loop it around the screw on the left side so as not to push it from under the screw when you tighten it. Then just pull up the end of the wire and bond it with the other grounds. Saves a pigtail and the additional wire in the box.

[DeathopTerokkar]

Watching your videos fills me with a mixed feeling of calm and terror. Calm because it reaffirms that the little bit of stuff that I've done recently is correct. Terror because I now realize that my dad had no clue what the hell he was doing when he wired up my childhood home and we just kinda got lucky codes and safety wise.

[veger]

1: GNH - HNG is the order ( Rule ) in which you assemble or de-assemble wiring. G= ground, N= Neutral, H= Hot. ( If the H is removed first then I always cap it first before proceeding )
2: For looping wires around terminals always loop in the same direction as the screw turns.

[Jade]

As I’ve been diving deeper into DIY electrical, I’ve developed a love for the metal boxes. I just want to thank you for your videos. Because of your concise but informative content, I have tackled quite a few projects that I at one time would have thought impossible. Thank you!

[gadgethunter]

Your example of having an energized switch box reminded me of way back at the dawn of time, when I was entering the gas trade, there was an exam question which dealt with switching the neutral. Don't switch the neutral. One day very early in my career I discovered why. I was changing a belted fan motor. So I switched off the furnace switch, then immediately got lit up trying to remove the wiring. The light bulb went on, and it finally all made sense. Training is great, but without field experience, questions will remain.

[anthonyzaradich]

The example of the early 1900s home is exactly everything I'm dealing with in trying to re-wire my house. Really appreciate all your videos here on these topics as they're helping me make sure that during my re-wiring projects I'm doing things properly and not leaving any "WTF was this guy thinking" for the next guy coming around.

Also big thanks to all the electrical guys in the comments as well for their takes and additional information they add. After watching videos like these, I like to go to the comments section and browse around for other opinions on the matter as well and they've been a big help -- so all you folks leaving those comments I just want you to know you've been mega helpful as well in learning.

[robinj]

Interesting to see the differences between countries. Here in the Netherlands, we do not use metal junction boxes, only plastic. I've never come accross a metal junction box in DIY shops. Probably to avoid short circuiting the circuit via the junction box itself. The Wago connectors are gems, I use them a lot in industrial applications as well.

We use different cables/wires as well. Never (flat) cable, only fully insulated wires for live, neutral, switch and ground. The wires are always run through flexible conduit.

[JoeJ-]

2 things to mention about the grounding straps/wire pigtails with the screws attached... First off, the screw they use is NOT a 6-32 screw, (like the plastic cover face plates of switches and outlets use), but instead it is actually almost always a self tapping 10-32 screw.

And the 2nd thing I was going to add is that those screws also usually can be driven into the hole in the metal boxes using a 5/16" hex driver tip. That is also a more reliable way to keep the screw straight and not get it crossthreaded, AND not to slip out of the screw head like especially a flathead screwdriver tends to do!

[TheForgottenMan]

I recommend that you don't secure the box to the vertical board of the truss. Cut the wires at a longer length and secure the box to the webbing of the truss as to keep it unburied out of the insulation. That way you can access it with ease without having to fight the insulation. Plus, you know exactly where to go to access it.

I sure hope you're putting covers on those boxes.

[rivernet]

Speaking of mistakes I make all the time, even though I know better: don’t use the knockout that’s right next to the grounding screw tower. The wiring just gets in the way.

[davidadam]

I like your videos because you speak slowly and clearly making it easy to understand what you're teaching. Very helpful and educational.

[KaraokeSC]

JoeJ8282 is correct - but these specific grounding screws are ALWAYS 10-32 screws, as is the grounding terminal hole in the box. The cover screws are 8-32, and device screws are almost all 6-32. The hex drive is a good idea too.

[bsmith]

Ground screws are 10/32 not 6/32 as you stated. Also the best tool is a 5/16 nut runner.

[xavariusquest]

Two important points. Determine where your lines are going to come in on the box. Then rotate the box so the lines don't interfere with the placement of the ground screw. Mount the box first. Then run the wires.

Second. You can use ground clips if you have a project in existing work and the old box has no threaded hole for a ground screw..

One last point. Always mount the appropriate cover for junction boxes. When you're done, use a permanent marker to indicate what purpose box services and what each wire is...power in, pass through, switch, outlet, appliance etc. This will be huge if you have a problem that someone else needs to address.