1 box, 2 circuits, 7 ground wires...

3296 Views 41 Replies 8 Participants Last post by Jim Port, Dec 27, 2015

iThinman

Discussion Starter · Dec 24, 2015

I am in the process of wires outlets in my shop and have a question about connecting ground wires.

Each of my 2-gang boxes will have 2 outlets, each from a separate circuit. Entering and exiting each box will be 2x 12/3, so I will have 4 grounds there, two from the receptacles and 1 from the box itself.

What it the proper method to connect all these grounds?

I have the screw in the box for that ground, can I also use clips and connect the grounds from the receptacles to those? Or is there some other way I can/should be connecting them?

The boxes are metal, 1 5/8 deep with 1 1/2 risers on them from total ~3" deep
12/3 mc cable

Thanks for any info!

1 - 20 of 42 Posts

iThinman

Discussion Starter · #2 · Dec 24, 2015

See less See more

darren

· #3 · Dec 24, 2015

Why are you using armoured cable?

Take the 4 grounds from the armoured cable, the green from the box, and two pigtails(to go the device) and twist them all together. Get a big enough marrete to cap it off.

Reactions: 1

iThinman

Discussion Starter · #4 · Dec 24, 2015

I'm going to leave the walls open so figured MC cable was better.

will I be able to get everything in a blue and stuff it in there?

rjniles

· #5 · Dec 24, 2015

Take 1 of the grounds to a green ground screw in the back of the box. Leave this wire about 15" long. Take the other 3 grounds and twist around the long one and connect with a green wire nut. Take the long ground sticking thru the hole in the green wire nut and loop to the 2 receptacles.

For box fill this counts as 1 conductor.

Reactions: 1

rjniles

· #6 · Dec 24, 2015

Just noticed you have a green pigtail in the box. Forget looping a ground in the back of box and add the pigtail under the green wire nut.

Reactions: 1

iThinman

Discussion Starter · #7 · Dec 24, 2015

hmmm, what you first described sounds pretty clean though and I don't mind removing the pigtail.

In the first description, I'm confused about stripping the 15" wire. Do I need to strip it mid-wire to loop on the box screw?

rjniles

· #8 · Dec 24, 2015

After the cable comes into the box leave a 15" free length to strip. Loop around the ground screw close to the cable entry.

Reactions: 1

Arrow3030

· #9 · Dec 24, 2015

I usually use industrial raised covers for this application. It finishes better IMO. If you get the cover with crushed corners you can avoid the grounding conductor to the receptacles.

Reactions: 1

iThinman

Discussion Starter · #10 · Dec 24, 2015

rjniles said:
After the cable comes into the box leave a 15" free length to strip. Loop around the ground screw close to the cable entry.

Got it, thanks. So it is ok to strip the entire 15" in this scenario and just make sure when I tuck in, it doesn't get near the sides of the receptacles?

Arrow3030 said:
I usually use industrial raised covers for this application. It finishes better IMO. If you get the cover with crushed corners you can avoid the grounding conductor to the receptacles.

Are these the covers you are talking about? I want to use them but it doesn't seem like I can with that riser on there. If I use without the riser, it's going to be much tighter in there. Which leads me to the question I really don't want to ask...Did I get the wrong boxes (too shallow)?

I'd really love to take advantage of not needing the ground conductor to the receptacle if I can.

See less See more

rjniles

· #11 · Dec 24, 2015

I used 15" as worst case, shorten as required. If you use self grounding receptacles, you can skip looping the grounds to the receptacles and just use a red wire nut on the grounds.

Reactions: 1

Arrow3030

· #12 · Dec 24, 2015

That is the cover I was referring to. Those covers do give a bit cu in. but probably not enough. How many 12/3's are there?

Rj is also correct on the self grounding receptacle. You can also use any metal yoke receptacle and remove at least one of the plastic retaining washers to avoid connecing the grounding conductor to the receptacles

Reactions: 1

iThinman

Discussion Starter · #13 · Dec 24, 2015

Yeah, they were def too shallow (1 5/8). Stores are closed early today and all tomorrow, so I ran out and got the correct (2 1/4) boxes. Now they fit good without the riser, so I can return those later. Needed room for the capped off unused hot from each 12/3, so the extra room from those risers were really blinding me from the correct combo.

There are 4x 12/3's (duplex mc connectors), so using the self grounding is really going to help.

I just built the easy end box (only 2x 12/3) and will snap a pic from a 4x in a little bit so we can point and laugh at my hopefully not too sloppy work.

Thanks to you both!

iThinman

Discussion Starter · #14 · Dec 25, 2015

Yeah, that works out really well. I struggle to stuff when the grounds are connected to the receptacles. This is much cleaner. Thanks again for the help.

How'd I do? I'm a keyboard & mouse guy.

See less See more

3

rjniles

· #15 · Dec 25, 2015

You will fail inspection. Cables need to be secured within 12" of box.

Also, most people would discourage the use of the back stabbing the receptacles. Use the screws or get back-wired receptacles. The white receptacle does not look like it is self grounding.

Merry Christmas

iThinman

Discussion Starter · #16 · Dec 25, 2015

I have some play on both ends and should be able to meet the securing requirement.

Kinda lost me on the second part. Not sure what back-wired or back stabbing refers to

They are both identical receptacles, just different colors. Leviton #5352. Both say "self-grounding when installed in properly grounded metal box" on the box.

Merry Christmas to you as well.

iThinman

Discussion Starter · #17 · Dec 25, 2015

Ok, looked it up. I'll make sure they are all trimmed properly and nice & tight, but if they don't want me using the back holes, they shouldn't put them there.

So much easier to deal with.

Arrow3030

· #18 · Dec 25, 2015

Those look better than a stab. Is there a plate on the receptacle that needed to be screwed tight or did the wire push in?

Reactions: 1

jbfan

· #19 · Dec 25, 2015

Why 4 12/3's?
When using MWBC, the neutrals are required to be pigtailed, and then connected to the receptacle.

Reactions: 1

iThinman

Discussion Starter · #20 · Dec 25, 2015

Arrow3030 said:
Those look better than a stab. Is there a plate on the receptacle that needed to be screwed tight or did the wire push in?

Yeah, there is a plate in there that tightens when you screw in the screw. It honestly looks to have much better coverage and holding power then wrapping the screw.

1 - 20 of 42 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.