Metal Box Cover Plates

[Little Bill]

I can't seem to find where in the code it says that device metal cover plates with flat corners don't require a jumper to the device. Can someone find that article for me? I'm talking about a 4 square box with an industrial raised cover.

 

[LarryFine]

I believe it's based on the cover-box interface being listed.

 

[wwhitney]

2017 NEC 250.146(A):

"(A) Surface-Mounted Box. Where the box is mounted on the surface, direct metal-to-metal contact between the device yoke and the box or a contact yoke or device that complies with 250.146(B) shall be permitted to ground the receptacle to the box. At least one of the insulating washers shall be removed from receptacles that do not have a contact yoke or device that complies with 250.146(B) to ensure direct metal-to-metal
contact. This provision shall not apply to cover-mounted receptacles unless the box and cover combination are listed as providing satisfactory ground continuity between the box and the receptacle. A listed exposed work cover shall be permitted to be the grounding and bonding means when (1) the device is attached to the cover with at least two fasteners that are permanent (such as a rivet) or have a thread locking or screw or nut
locking means and (2) when the cover mounting holes are located on a flat non-raised portion of the cover."

Cheers, Wayne

 

[LarryFine]

"This provision shall not apply to cover-mounted receptacles unless the box and cover combination are listed as providing satisfactory ground continuity between the box and the receptacle."

This is the part I was thinking of.

 

[Little Bill]

2017 NEC 250.146(A):

"(A) Surface-Mounted Box. Where the box is mounted on the surface, direct metal-to-metal contact between the device yoke and the box or a contact yoke or device that complies with 250.146(B) shall be permitted to ground the receptacle to the box. At least one of the insulating washers shall be removed from receptacles that do not have a contact yoke or device that complies with 250.146(B) to ensure direct metal-to-metal
contact. This provision shall not apply to cover-mounted receptacles unless the box and cover combination are listed as providing satisfactory ground continuity between the box and the receptacle. A listed exposed work cover shall be permitted to be the grounding and bonding means when (1) the device is attached to the cover with at least two fasteners that are permanent (such as a rivet) or have a thread locking or screw or nut
locking means and (2) when the cover mounting holes are located on a flat non-raised portion of the cover."

Cheers, Wayne

The "2" was what I was looking for.
Thanks!

 

[tom baker]

The trade name is crush corner. The old style raised covers are hard to find. Installing a receptacle in a raised cover with those 6/32 screws and nuts is not easy for me!

 

[lordofthisworld]

I can't seem to find where in the code it says that device metal cover plates with flat corners don't require a jumper to the device. Can someone find that article for me? I'm talking about a 4 square box with an industrial raised cover.

Mulberry cover?

 

[infinity]

Mulberry cover?

That's what we call them.

 

[hbiss]

Austin cover.

-Hal

 

[Little Bill]

Mulberry cover?

That's what we call them.

I've heard them called that. My S/H lists them as "raised industrial covers".

 

[infinity]

Mulberry is the brand name of the covers that we typically see when we order them locally. You can see their double M symbol on the face of the cover.

 

[Little Bill]

Mulberry is the brand name of the covers that we typically see when we order them locally. You can see their double M symbol on the face of the cover.
View attachment 2574233

That doesn't appear to have the flat/indented corners.

This is what I'm referring to.

 

[LarryFine]

The 4-11/16" cover was an example of the kind that doesn't qualify, unless the combination does.