I was recently speaking with a guy who owns his own electrical contracting business. He is currently taking inspector classes for NJ and the topic of self grounding receptacles came up. He told me that in the class they were teaching them that in a "1900 slap-on w/ mudring" situation self-grounding receptacles shall not be used as per NEC. Section 250.142 (B) mentions that self-grounding receptacles shall be permitted with flush-type electrical boxes. So, is a mudring and 1900 slap-on not considered a flush type box, or are they teaching this subject incorrectly in the class? It was always my understanding that the screw threads completed the grounding path in this and similar situations, thus making a self-grounding receptacle a relevant product.
Self Grounding Receptacles
- Thread starter DBrede
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
You can use a self grounding receptacle with a mud ring to ground the device since that would be a flush-type box. Here's the section:
Last edited:
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I think you mean 250.146(B)-- 2008. What year are you looking at?
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
So if the mud ring is set back an 1/8"????
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Yes, you're right I've changed it.
Would that matter? It doesn't change the fact that you've installed a flush-type box.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Can we argue that the box is not flush. Firstly, it is the ring that makes it flush :grin: and secondly, it isn't flush.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Yes we can argue about anything here. :grin:
IMO the requirement applies to flush-type boxes not flush boxes.
yes that is the correct code, i apologize i was going off memory which is sometimes unreliable. i have not been able to find what is UL listed or officially carries the label of flush-type box. it seems that this argument depends on that. however, when testing hot-to ground and neutral-to-ground in the mud-ring scenario all tests have been correct when i have used self-ground receptacles. maybe a RACO or STEEL CITY rep can chime in about the boxes
mcclary's electrical
Senior Member
- Location
- VA
IMO, 250.146 (a) ('05) starts out with "where the box is mounted onthe surface",,,,,,,sure once you get to (b) they don't mention it again, but it's still talking about the same surface mounted box .
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I would have to disagree with your reasoning. 250.146 says "An equipment bonding jumper shall be used to connect the grounding terminal of a grounding-type receptacle to a grounded box unless grounded as in 250.146(A) through (D)."
(A), (B), (C), & (D) are four separate items.
I would agree that they are 4 separate items as well. I was browsing through mike holt's grounding versus bonding book today and saw his example showed and included the wording "box and mudring." The picture was the most common situation where a self-ground receptacle would be used. Another thought I had was that in order to maintain the UL listing, when using a self-ground receptacle one must not alter in any way. By this I mean replacing either of the provided 6-32 screws with longer screws, as in the case of the box and mudring being set back too far.
6-32s that are an inch longer wont be able to clear a fault, or what?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I think that he's saying that by using different screws, other than ones that were installed as part of the listing, would violate the listing of the device.
As long as it's the same material, is it really a safety issue though?
kwired
Electron manager
- Location
- NE Nebraska
I think you mean section 250.146(B), and I am on your side it is a flush box as installed.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Unless the screw is suddenly non-metallic I don't think so. :roll:
myrshub
Member
- Location
- central CA
Woyuld this also apply to regular receptacle once you remove the washers from behind the yoke making metal to metal contact woth the mudring?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
No that's only for a surface mounted box not a flush type.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Point to ponder: Is the last sentence of 250.146(A) applicable for such an in-wall box-and-mudring combination, or do we presume any combo is adequate?
Hmmm. :roll:
Hmmm. :roll:
- Status