Grounding receptacles

[Alwayslearningelec]

Ok so I am doing some studying/reading tonight and I see that if using conduit with a flush mounted box you must bond the receptacle to the box. If using a surface metal box this is not necessary because of the metal to metal contact of the yoke and box. If a raised cover is used you must use a bonding jumper . Not sure why though. There are receptacles now with special screws and yokes that provided and effective bond.... So my book says. Thanks

 

[480sparky]

There's a difference between mounting a device to a box and mounting a device to a cover. And that difference is when mounting to a box, you can remove the cover and the device is still physically attached (and grounded) to the box. When using a raised cover, the cover in effect becomes the EGC, which it is not listed to be used as such.

 

[infinity]

When using a flush mounted box the ears of the device are resting on the Sheetrock and only the screws are connecting the device to the box so something additional is required for bonding the two together (a jumper or selfgrounding device). When the box is surface mounted you can have direct metal to metal contact between the yoke and the box itself, this would be for an FS type box or "handy" box. A surface cover used for a surface mounted 4" box with the dimples where the mounting screws are does not require a bonding jumper because all of those covers are listed for grounding the device.

 

[Dennis Alwon]

BTW you still need to bond the box when using a surface mount setup. The receptacle does not need to be bonded to the box because, as stated the screws and cover give a solid connection to the bonded box.

 

[Alwayslearningelec]

BTW you still need to bond the box when using a surface mount setup. The receptacle does not need to be bonded to the box because, as stated the screws and cover give a solid connection to the bonded box.[/QUOTE

Ok I was following up to here. How is the box bonded? I though when the recpt is binded to the box the box is bonded which would be the case in surface mounted. THanks.

 

[Dennis Alwon]

BTW you still need to bond the box when using a surface mount setup. The receptacle does not need to be bonded to the box because, as stated the screws and cover give a solid connection to the bonded box.[/QUOTE

Ok I was following up to here. How is the box bonded? I though when the recpt is binded to the box the box is bonded which would be the case in surface mounted. THanks.

The box needs to be bonded without the device installed. If you are using emt or metal raceways then it is not an issue unless you run a egc. In that case the egc needs to get connected to the metal box. The receptacle is then bonded to the box via the surface cover.

 

[Alwayslearningelec]

The box needs to be bonded without the device installed. If you are using emt or metal raceways then it is not an issue unless you run a egc. In that case the egc needs to get connected to the metal box. The receptacle is then bonded to the box via the surface cover.

GOt it thanks. So the MC jacket would bond the box without a recptacle...correct? What about when using romex? THanks.

 

[Dennis Alwon]

GOt it thanks. So the MC jacket would bond the box without a recptacle...correct? What about when using romex? THanks.

The mc alone is not an egc unless it is MC AP. Thus it would be treated as NM cable and the equipment ground wire must be tied to the metal box.