250.146(a)

[cowboyjwc]

Because of budget cuts, we had to put off getting training materials so I actually just got mine a few days ago, just in time to start training so I'm seeing some of these changes as I'm teaching them.

Saw this one this morning and it reminded me that we had had a discussion about this not to long ago.

Just wondering if any of you thought that the type of cover with with the mounting holes on the non-raised portion would really make that much more difference than the mounting holes on the raised portion?

Doesn't seem like a big deal, but this is the kind of change that get's inspectors in trouble, because "that's the way we've always called it".:grin:

 

[chris kennedy]

Even the non-raised portion is slightly raised, so I don't really get it. FWIW, we still pig-tail to the device with this cover, takes an extra 20 seconds.:roll:

 

[augie47]

I had not paid any attention to the change until you mentioned it, but then I referred to the Handbook, and, it appears to me, the Exhibit 250.56 shows the opposite of what the wording says. Anyone ?

 

[chris kennedy]

Hey guys, read this, do we all have it wrong?

Commentary;

Cover-mounted wiring devices, such as on 4-in. square covers, are not considered grounded. Section 250.146(A) does not apply to cover-mounted receptacles, such as the one illustrated in Exhibit 250.56. Box-cover and device combinations listed as providing grounding continuity are permitted. The mounting holes for the cover must be located on a flat, non-raised portion of the cover to provide the best possible surface-to-surface contact and the receptacle must be secured to the cover using not less than two rivets or locking means for threaded attachment means.

 

[augie47]

From reading the NEC it appears the Handbook has the commentary and Exhibit wrong, but it's probably me.

 

[chris kennedy]

From reading the NEC it appears the Handbook has the commentary and Exhibit wrong, but it's probably me.

Stallcups and the IAEI change books both show a 4" square cover as being compliant.

 

[cowboyjwc]

Stallcups and the IAEI change books both show a 4" square cover as being compliant.

I got it out of the Analysis of Changes and it shows that if you use the cover that you can use the 1/2" screws on then it would not need to be pigtailed, but if you use the other cover it would need to be. You also have to use a rivit or the screw and nut that come with it to mount it to the cover, at least that's the way I understand it.

You know what Gus, now that I've looked at the handbook, you're correct, that's what it looks like to me too. They're talking about you don't need the pigtail if you remove the fiber washer, then it says that 250-146(A) does not apply to cover mounted receptecales, but that's the picture they show in the Analysis and the power point I have.

 

[infinity]

Here's a post from a similar thread from a few days ago. The photo in the 2008 NECH is incorrect:

Quote:
Originally Posted by wbrown66
In the 2008 NEC handbook the picture in Exhibit 250.56 pg 254, shows a raised cover with a flat-nonraised portion for the cover mounting screw holes. In the picture there is text that states "Bonding jumper required..." In my mind I thought that this was a perfect picture for when an EG jumper is NOT required. For any of you who have the 08 handbook, can you tell me what I am missing. Besides that the picture is not enforceable.


I thought I would post here instead of opening a new thread.

Thanks

I agree with you. The photo is likely incorrect. They used the same photo in the 2005 NECH. My guess is that the cover should have been one of these:

 

[chris kennedy]

You know what Gus, now that I've looked at the handbook, you're correct, that's what it looks like to me too. They're talking about you don't need the pigtail if you remove the fiber washer, then it says that 250-146(A) does not apply to cover mounted receptecales, but that's the picture they show in the Analysis and the power point I have.

From reading the NEC it appears the Handbook has the commentary and Exhibit wrong

I believe Gus is right.

 

[cowboyjwc]

Thanks Rob, that's the thread I was talking about, but if you read the text it says "cover mounted receptacles" it doesn't really mention different types of raised covers. Unless they consider the covers with the mounting screws on the non-raised portion the same as removing the washer and mounting the receptacle to a metal box.

I'm kind of with Chris, I don't know that I would really change the way I do it after all these years, but I want to be fair to the guys who do it different.

 

[infinity]

This wording was added to the 2008 NEC because the dimpled covers were already listed for grounding. The new wording makes it so that you don't need to go the the listing of the cover to find that information. With two screws holding the device to the cover and two screws holding the cover to the box I don't see a problem. IMO the cover in the photo I posted seems less likely to provide adequate contact with the box.