Welder Outlet Ground Size

[nwav8tor]

I'm planning to install a 50A 220V welder outlet in my garage using a metal 2 gang box. Power will come from a new subpanel via 6-2 w/grnd romex. Now for the questions:

1) Is a ground wire and screw required to ground the metal box or is the integral ground strap from the outlet's ground lug to the metal plate the outlet is mounted on sufficient, since the metal plate will connect directly to the metal box?

2) If an actual ground wire and screw are required to ground the box, what AWG is needed and is that secured in the outlet's ground lug along with the romex's ground wire (which I assume is #8)?

Thanks,
Paul

 

[matt151617]

I believe you will need another 8 gauge pigtail (although 10 is allowed also), connected to the other ground, and connected to the box.

 

[Norcal]

All metal boxes need to be bonded to the grounding conductor, there is a 10/32 tapped spot on metal boxes for that purpose, the 10 AWG conductor part of the NM cable assembly is fine. This only works if sufficient length has been left but I like to wrap the the bare grounding conductor around the grounding screw unspliced, & continue on to the device, simple & no pigtail required.

 

[pattenp]

Even though I like to jumper the ground to the receptacle in a metal box, it is not required if the receptacle is self grounding via the yoke. NEC 250.146(B)

Oh... and ditto on the #10 for ground. The ground in the NM 6-2 should be a #10.

 

[sberry]

We went thru that, the welder recept yoke is grounded but isnt technically listed as self grounding. To add, if it was a surface mount just wire it up, if it was screwed in to a box it wouldnt bother me a lot but if it is mounted in a cover must be box grounded.

 

[Speedy Petey]

All metal boxes need to be bonded to the grounding conductor, there is a 10/32 tapped spot on metal boxes for that purpose, the 10 AWG conductor part of the NM cable assembly is fine. This only works if sufficient length has been left but I like to wrap the the bare grounding conductor around the grounding screw unspliced, & continue on to the device, simple & no pigtail required.

Exactly.

 

[Speedy Petey]

Even though I like to jumper the ground to the metal box, it is not required if the receptacle is self grounding via the yoke. NEC 250.146(B)

Actually the opposite is true.
The box must always be grounded(bonded), but a tail to a receptacle is not always required. A self-grounding receptacle mounted to a metal box does not need a tail.

 

[pattenp]

Actually the opposite is true.
The box must always be grounded(bonded), but a tail to a receptacle is not always required. A self-grounding receptacle mounted to a metal box does not need a tail.

I'm with you. In my head I thought that's what I meant. I corrected my statement in bold.

"Even though I like to jumper the ground to the receptacle in a metal box, it is not required if the receptacle is self grounding via the yoke. NEC 250.146(B)"

 

[nwav8tor]

OK, Just to see if I have this straight:

1) If the outlet is NOT listed as self-grounding, I need a #10 pigtail (or a long portion of the romex ground wire) to connect the box's ground screw to the outlet's ground lug and/or the incoming romex ground. In this case, can I just put 2 #10 into the outlet's ground lug (1 from the incoming romex and one back to the box's ground screw)? Where can I look to see if the outlet's ground lug can legally take 2 #10s?

2) If the outlet IS listed as self-grounding, then only a single ground connection is required.

Pattenp and Speedy Petey said the romex ground should go to the BOX and a pigtail to the outlet isn't required. Is that correct? I wonder why it isn't the other way around. i.e. if the outlet is self-grounding, wouldn't the box be grounded also if the romex ground went to the outlet's ground lug rather than the box's ground screw?

Wish I was home so I could check the outlet packaging to see if it's listed as self-grounding...

Paul

 

[Norcal]

I have not seen a "self grounding" 30 or 50A straight blade device, but if it was, the box needs to be bonded to the grounding conductor.

 

[Speedy Petey]

1) If the outlet is NOT listed as self-grounding, I need a #10 pigtail (or a long portion of the romex ground wire) to connect the box's ground screw to the outlet's ground lug and/or the incoming romex ground. In this case, can I just put 2 #10 into the outlet's ground lug (1 from the incoming romex and one back to the box's ground screw)? Where can I look to see if the outlet's ground lug can legally take 2 #10s?

No, you cannot put two wires under the same screw/terminal. Like I said, hit the box first and continue on to the receptacle.

2) If the outlet IS listed as self-grounding, then only a single ground connection is required.

Yes, to the box.

Pattenp and Speedy Petey said the romex ground should go to the BOX and a pigtail to the outlet isn't required. Is that correct? I wonder why it isn't the other way around. i.e. if the outlet is self-grounding, wouldn't the box be grounded also if the romex ground went to the outlet's ground lug rather than the box's ground screw?

Because the box is always there. If there is a self-grounding receptacle there now what if someone changes it later? The metal box is the constant.

I have not seen a "self grounding" 30 or 50A straight blade device, but if it was, the box needs to be bonded to the grounding conductor.

I agree. I've never seen one either.

 

[nwav8tor]

Thanks Speedy and Norcal,

I now understand the logic for grounding the box instead of the outlet if the outlet is self-grounding. I hadn't ever thought about what happens if/when the outlet is removed...

I remember seeing some type of a metal strip on the outlet that went from the ground lug to the mounting plate. Not sure if that means its self-grounding or not. I guess it doesn't matter if the packaging/instructions don't specifically say that it's self-grounding. When I get back home I'll confirm it and post a pic...

Paul

 

[nwav8tor]

Here's the label from the box my outlet came in.

Note that it says "Grounding." Am I correct to assume that the label actually means it's self-grounding???

It also says "GRDG" on the outlet itself, does that mean self-grounding?

Here's a pic of the back of the outlet that shows the metal strip going from the ground lug to the metal mounting plate:

Now with all this information, along with the fact that I'm using 6-2 romex w/grnd, if I connect the ground in the romex right to the metal box grounding screw, do I need to run a tail from the ground screw to the outlet's ground lug, or will the outlet itself already be grounded to the box once it's mounted?

Thanks,
Paul

 

[Ironhorse]

I'm planning to install a 50A 220V welder outlet in my garage using a metal 2 gang box. Power will come from a new subpanel via 6-2 w/grnd romex. Now for the questions:

1) Is a ground wire and screw required to ground the metal box or is the integral ground strap from the outlet's ground lug to the metal plate the outlet is mounted on sufficient, since the metal plate will connect directly to the metal box?

2) If an actual ground wire and screw are required to ground the box, what AWG is needed and is that secured in the outlet's ground lug along with the romex's ground wire (which I assume is #8)?

Thanks,
Paul

Yes the ground screw is required to bond the metal box. and no it will not be self grounding or bonded ( you do not have EMT run to the box and I will assume you do not have a metal stud wall as well)

So all you need to do is buy or make a "pig tail" and screw it to the back of the box ( rasied portion or 10/32 hole) You have to used a green colored screw ( this way when finished you really do not need to open the box to see if there is a ground screw in it or not, mostly for rough in inspections easy to look at them in an open stud wall and see if the boxes are bonded or not.) Take the ground in your 6-2, the ground in the back of the box, and a third #10 green wire 6" or so wirenut them all toghter with a blue wire nut...then with the three remaining wires put the correctlly in your recpt. ( the other end of the 6" ground wire would be your ground of course) Do not for get after it is all said and done make sure your wire above the box is attached 8" above the box...

 

[Norcal]

Yes the ground screw is required to bond the metal box. and no it will not be self grounding or bonded ( you do not have EMT run to the box and I will assume you do not have a metal stud wall as well)

So all you need to do is buy or make a "pig tail" and screw it to the back of the box ( rasied portion or 10/32 hole) You have to used a green colored screw ( this way when finished you really do not need to open the box to see if there is a ground screw in it or not, mostly for rough in inspections easy to look at them in an open stud wall and see if the boxes are bonded or not.) Take the ground in your 6-2, the ground in the back of the box, and a third #10 green wire 6" or so wirenut them all toghter with a blue wire nut...then with the three remaining wires put the correctlly in your recpt. ( the other end of the 6" ground wire would be your ground of course) Do not for get after it is all said and done make sure your wire above the box is attached 8" above the box...

Keep it simple, if there is enough slack wire in the box just get a 10/32 ground screw & wrap the bare 10 AWG around it then continue out to the receptacle, then no need for any splices in the grounding conductor, & the box is bonded to the grounding conductor.

 

[Speedy Petey]

Now with all this information, along with the fact that I'm using 6-2 romex w/grnd, if I connect the ground in the romex right to the metal box grounding screw, do I need to run a tail from the ground screw to the outlet's ground lug, or will the outlet itself already be grounded to the box once it's mounted?

NO, this is NOT a "self-grounding" receptacle.
You must run a tail to this device.

May I ask what the big deal is doing this? It's really nothing.

 

[nwav8tor]

NO, this is NOT a "self-grounding" receptacle.
You must run a tail to this device.

May I ask what the big deal is doing this? It's really nothing.

It's NOT a big deal, I was just curious as to what a self grounding outlet was and how it was labeled/identified. I have already taken the ground from the romex to the grouind screw on the metal box and then to the outlet's ground ...

Paul

 

[Speedy Petey]

See the clip in the screw hole on this receptacle? That is what makes it self-grounding. It enhances the continuity of the receptacle to the box.

 

[gatchel]

NO, this is NOT a "self-grounding" receptacle.
You must run a tail to this device.

May I ask what the big deal is doing this? It's really nothing.

+1

Make it more safer!

 

[Speedy Petey]

+1

Make it more safer!

It's saferer. Get your spelling right.