"Self grding" receptacles & 250.148(C)

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brentp

Senior Member
I would like some opinions on whether the grding clip on a self grding duplex receptacle will satisfy the requirements of metal box bonding in 250.148(C).

Installation is emt with a copper egc spliced within a recessed metal outlet box.

The debate is whether or not the grding clip along with the receptacle supporting screws is "equipment listed for grounding, or a listed grounding device" as stated in 250.148(C). If so, no bonding pigtail would be required.

I have always installed a "pigtail" to bond the box, but I also see validity in the other side's argument. It would be nice to settle this without the "what if the receptacle is removed", although I don't know if that's possible.

I might be asking for a little much here, but technical "proof" would be nice if someone has it. I have searched and come up short.

Anyway, thanks in advance.

Brent
 

Hendrix

Senior Member
Location
New England
I would like some opinions on whether the grding clip on a self grding duplex receptacle will satisfy the requirements of metal box bonding in 250.148(C).

Installation is emt with a copper egc spliced within a recessed metal outlet box.

The debate is whether or not the grding clip along with the receptacle supporting screws is "equipment listed for grounding, or a listed grounding device" as stated in 250.148(C). If so, no bonding pigtail would be required.

I have always installed a "pigtail" to bond the box, but I also see validity in the other side's argument. It would be nice to settle this without the "what if the receptacle is removed", although I don't know if that's possible.

I might be asking for a little much here, but technical "proof" would be nice if someone has it. I have searched and come up short.

Anyway, thanks in advance.

Brent
I think that your interpretation of the article is correct and you would not need a pigtail. Look at exhibit 250.55 in the handbook. As well as 250.57
 
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LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Brent, a self-grounding receptacle permits omitting the GEC to the receptacle, but never to the box. In other words, the box must be bonded to the EGC, whether or not a jumper is attached to the receptacle.
 

aftershock

Senior Member
Location
Memphis, TN
would not the yoke of the device need full contact of the metal box (along with the screws) in order to keep from landing a ground on the device? such as a surface mount box?
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
would not the yoke of the device need full contact of the metal box (along with the screws) in order to keep from landing a ground on the device? such as a surface mount box?

No, the self-grounding device is all that's required.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I agree with Rob, but you would still need the pigtail if you were using a raised cover, unless the box and cover, together, are approved for grounding.


True, and the 2008 NEC adding wording stating that these covers with dimples at the sides are so listed.
 

brentp

Senior Member
I agree with you Larry. The recept may be grounded via the box, but not the box grounded via the recept. I don't believe the the Code's intent in 250.148(C) was for the recept yoke, clip & screws to be a "listed grounding device" used for box bonding. I'm having a hard time selling it tho'.

Me: You need to bond that box with a jumper.
Them: But I'm using emt, its already bonding the box.
Me: Yeah, I know, but you still have to bond the box with the wire, you have a splice in it.
Them: But its a self grding recept, grd wire to screw, thru the yoke, clip, screws & in to the box. It's grded again.
Me: You're right, but you can't do it that way.
Them: So if I pulled the wire out, everything would be ok?
Me: Yes.
Them: That doesn't make much sense.
Me: Read 250.146 & 250.148 & get back with me.

Next day...

Them: I read the articles you told me to.
Me: Great! So you understand!?
Them: Kinda...BUT, isn't the receptacle yoke, clip & screws a listed grounding device?
Me: Yeah, I guess so.
Them: Well, that's what it says in 250.148, to use a listed grounding device to bond the box. That's what I have.
Me: I don't think that's the intent of the Code.
Them: But that's what it says.
Me: I'll get back to you.

Me: Go home & type in Mike Holt.com. I don't know what else to say. Help me out here guys. :)
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I have never understood how the grounding device on a self grounding receptacle only permits fault current to flow from the receptacle to the box. How does it prevent the fault current from flowing from the box to the receptacle?

In other words if it is a fault clearing path from the receptacle to the box, there is no technical reason why it can't be a fault clearing path from the box to the receptacle. To me the preferred method, where you have a EGC of the wire type, should be that the EGC is landed on the receptacle and the box is bonded by the self grounding screw. From a safety standpoint the most important EGC connection is the one to the receptacle. I don't think that there is any question that the direct connection of the EGC to the receptacle is far superior to using the self grounding device.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
I don't think that there is any question that the direct connection of the EGC to the receptacle is far superior to using the self grounding device.
I don't disagree with you there, Don. Look at it like the requirement that a shared neutral be spliced, and never dependent on the presence of a device to maintain its continuity.

It may be a far-fetched example, but, if you pulled every receptacle on a circuit that was wired your way, the boxes would become unbonded (lacking an intact conduit system.)
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
...
It may be a far-fetched example, but, if you pulled every receptacle on a circuit that was wired your way, the boxes would become unbonded (lacking an intact conduit system.)
If I am pulling the receptacles, the circuit should be locked out:D
 
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