Conduit grounding question

[Mr. T]

I ran into this situation today and thought I'd ask what someone else might do.

120V 20A circuit in an industrial building. Two 12AWG THHN conductors in EMT with the conduit serving as the EGC. Do you ground the receptacle with a pigtail too or do you trust the screws securing the receptacle to the box?

Also, some circuits have a parallel insulated ground when they break off at a junction and others don't. Is there any issue with this, i.e. does the entire branch circuit have to be wired consistently as far as the EGC goes?

Any help is appreciated. I know a little about a lot but I'm not sure if I should call an electrician in for this one or if it's okay to leave it the way it is.

 

[sberry]

Is the recept screwed in to the box or cover mounted?

 

[Mr. T]

Screwed into the box. Although I did find one that was cover mounted as well.

 

[Ch3No2]

Why not use a Ground Pigtail and be done?
I thought all commercial required pigtails....

 

[3rdgen]

Good practice is running a ground in EMT, but according to the code here it is not required (states may be different) but you do have to pig tail a ground from box to receptacles as the screws are not sufficient.

 

[Cmreschke]

Depends on whether or not it is a self grounding receptacle, and whether the conduit enters the box via concentric or eccentric knockout.
Also local amendments to the code book may supercede.

 

[wyliesdiesels]

Depends on whether or not it is a self grounding receptacle, and whether the conduit enters the box via concentric or eccentric knockout.
Also local amendments to the code book may supercede.

Depends on the receptcile.

Yes the conduit can be used as the EGC.

 

[djjsr]

..... but you do have to pig tail a ground from box to receptacles as the screws are not sufficient.

Hmmmm .......... I have dozens of receptacles mounted in metal boxes connected by metal conduit. No ground wires and no pigtails anywhere but they all test ok for ground. Most have been there since around 1970. No problem so far. What should I be concerned about?

 

[wyliesdiesels]

Hmmmm .......... I have dozens of receptacles mounted in metal boxes connected by metal conduit. No ground wires and no pigtails anywhere but they all test ok for ground. Most have been there since around 1970. No problem so far. What should I be concerned about?

Im not sure what hes referring to as an outlet that is listed as self grounding is sufficient....

 

[zmaxmotorsports]

Its only mechanically grounded as long as the outlet is screwed to the box,if its pulled out for servicing or whatever reason you lose it.
Put a pid tail to the box,its not a big deal.
One of these days Ill tell you guys about the perfect storm of an open neutral /and the conductivity of dead roach bodies between an outlet and a metal box/conduit.

 

[alfredeneuman]

As stated before, use a self-grounding receptacle.
The conduit, when properly installed, is more effective than the ground wire in a Romex.

Ch3No2
"I thought all commercial required pigtails.... " They don't

 

[Cmreschke]

Its only mechanically grounded as long as the outlet is screwed to the box,if its pulled out for servicing or whatever reason you lose it.
Put a pid tail to the box,its not a big deal.
One of these days Ill tell you guys about the perfect storm of an open neutral /and the conductivity of dead roach bodies between an outlet and a metal box/conduit.

So what if you pull it out and it's not grounded, as it doesn't need to be at that point because you shut the circuit off to work on it.

 

[Mr. T]

Update: I added pigtails and replaced a few of the old handy box/conduit connectors. At least it made me feel better.

Word of warning, the next time you're tasked with replacing "one broken receptacle" in a 40 year old industrial building Just run!

 

[Ainsley]

Personal opinion but I don't like using EMT as a ground. Rigid is a different story.

 

[Mr. T]

I don't like it either. But "they" weren't interested in paying to run 300' + of new wire.

I do what I can when I can. At least now it's safer than it was.