dryer receptacle in metal box

[KVA]

Dryer receptacle in 4" square with raised industrial cover. The yoke of the receptacle is bonded to the cover and the cover is bonded to the box with the 6/32s. You still need a bonding jumper from the box right?

 

[infinity]

Not if the 1900 cover has dimples at the corners. Those covers are listed for grounding. Similar to these:

 

[texie]

Dryer receptacle in 4" square with raised industrial cover. The yoke of the receptacle is bonded to the cover and the cover is bonded to the box with the 6/32s. You still need a bonding jumper from the box right?

Well, I think there are some things to consider first. If you supply this box with a qualified EGC conduit that has no separate EGC conductor, then I think Infinity is correct. Now if you supply that same box with NM cable or use a separate EGC in a metallic conduit system, then the EGC would have to be bonded to the box in an approved manner, but it would not have to be bonded to the EGC terminal of the recep. In other words, you can't run an EGC and just connect it to the recep. and not the box.
By the way, I think you mean 8/32 screws?

 

[kwired]

Well, I think there are some things to consider first. If you supply this box with a qualified EGC conduit that has no separate EGC conductor, then I think Infinity is correct. Now if you supply that same box with NM cable or use a separate EGC in a metallic conduit system, then the EGC would have to be bonded to the box in an approved manner, but it would not have to be bonded to the EGC terminal of the recep. In other words, you can't run an EGC and just connect it to the recep. and not the box.
By the way, I think you mean 8/32 screws?

6/32 screws typically would hold the device to the cover though.

 

[norcal]

Are there any "self-grounding" dryer receptacles? Or any 30 or 50 ampere devices for that matter.

 

[infinity]

Are there any "self-grounding" dryer receptacles? Or any 30 or 50 ampere devices for that matter.

I don't think so and it might have something to do with the 6/32's ability to carry the greater fault current on a 240 volt circuit. In the case of the OP a self-grounding device is not required.

 

[kwired]

I don't think so and it might have something to do with the 6/32's ability to carry the greater fault current on a 240 volt circuit. In the case of the OP a self-grounding device is not required.

I have to disagree with the fault current being greater. Many times it very well may be greater, but it doesn't have to be. Voltage is only part of the recipe for fault current level, and available fault current can very well be higher in some cases at the 120 volt level.


I have never seen a 30 or 50 amp device with the "self grounding" device yokes like you may find on certain 15 or 20 amp devices. Those "self grounding" devices really only necessary when used in a not quite flush metallic box where the yoke is not in secure contact to the metal box. If the device yoke sits in direct contact with the metal box that is acceptable bonding between the box and device and I see nothing in the NEC that limits this to a particular voltage, branch circuit amperage, or available fault current level. Just so happens that you never see any 30 or 50 amp devices with "self grounding" yokes, and if not mounted in a way that they make secure contact with a grounded metal box, then you must use a bonding jumper to ensure the device is connected to the EGC.

 

[infinity]

Those "self grounding" devices really only necessary when used in a not quite flush metallic box where the yoke is not in secure contact to the metal box. If the device yoke sits in direct contact with the metal box that is acceptable bonding between the box and device and I see nothing in the NEC that limits this to a particular voltage, branch circuit amperage, or available fault current level. Just so happens that you never see any 30 or 50 amp devices with "self grounding" yokes, and if not mounted in a way that they make secure contact with a grounded metal box, then you must use a bonding jumper to ensure the device is connected to the EGC.

This is incorrect. A recessed metal box is not permitted to provide a ground connection simply though the 6-32 screws even if it is in direct contact with the yoke of the device. Either a bonding jumper or a self grounding device is required.

 

[kwired]

This is incorrect. A recessed metal box is not permitted to provide a ground connection simply though the 6-32 screws even if it is in direct contact with the yoke of the device. Either a bonding jumper or a self grounding device is required.

I can probably agree with that - did not look it up but trust you are right. But still you can install said device in a surface mounted box without any bonding jumper to the device if the device makes metal to metal contact to the grounded box, and would not matter if the device has a "self grounding yoke" or not. I don't think you would find one that is self grounding, but if you did, it is probably been tested for such use or they wouldn't take the effort to even make it that way.