MC cable & grounding. Tail to the box & receptacles?

[Sir String]

12/2 MC cable in a 5" box.
You take the green wire & secure it to the box with a green ground screw. Thus grounding the box.

Do you also need to bring a tail to the ground screw of a duplex receptacle?

If yes, why? If the box is grounded, then so is the receptacle through the 6/32 screws. Or alternately, if the receptacle is grounded, then the box is grounded through the 6/32's.

I'm feeding a 5" box for quad receptacles plus 2 12/2 jumpers to other boxes. I end up with 6 grounds under a wire nut.

 

[infinity]

The 6-32 screws alone are not permitted to ground the receptacle. The device would need a bonding jumper or must be a self grounding receptacle. Also you cannot connect the EGC to the device and ground the metallic box through the device.

 

[jumper]

The 6-32 screws alone are not permitted to ground the receptacle. The device would need a bonding jumper or must be a self grounding receptacle. Also you cannot connect the EGC to the device and ground the metallic box through the device.

If this is a metal box that has the EGC bonded to it, wouldn't a regular receptacle with the plastic washers removed and metal to metal ( yoke to box) be okay?

 

[Sir String]

I meant self-grounding receptacles.

That's always been good enough with Bx. The jacket of the Bx bonding the box & the 6/32's grounding the receptacle.
So why not with MC cable?

I know I'm conflating 'bonding' & 'grounding' but that's a whole other issue with it's own section of the forum.

 

[infinity]

If this is a metal box that has the EGC bonded to it, wouldn't a regular receptacle with the plastic washers removed and metal to metal ( yoke to box) be okay?

Not for the box he's using.

I meant self-grounding receptacles.

That's always been good enough with Bx. The jacket of the Bx bonding the box & the 6/32's grounding the receptacle.
So why not with MC cable?

I know I'm conflating 'bonding' & 'grounding' but that's a whole other issue with it's own section of the forum.

If the receptacle is self grounding you can use it without a bonding jumper for either AC or MC to a grounded metal box. If it's not self grounding you need a bonding jumper for either of those wiring methods.

 

[Cow]

If you switched to MCap and self grounding receps, you wouldn't have to splice any grounds.

 

[cadpoint]

If you switched to MCap and self grounding receps, you wouldn't have to splice any grounds.

Better get more wire...

Third sentence in 250.64, + ...shall apply at each end... between cabinet or equipment... continually

 

[Finite10]

12/2 MC cable in a 5" box.
You take the green wire & secure it to the box with a green ground screw. Thus grounding the box.

Do you also need to bring a tail to the ground screw of a duplex receptacle?

If yes, why? If the box is grounded, then so is the receptacle through the 6/32 screws. Or alternately, if the receptacle is grounded, then the box is grounded through the 6/32's.

I'm feeding a 5" box for quad receptacles plus 2 12/2 jumpers to other boxes. I end up with 6 grounds under a wire nut.

I'd go with406.3(C)
The EGC contacts of a recept... shall be grounded by connection to the EGC of the circuit supplying the recept.

The branch circuit wiring method shall include or provide an EGC to which the EGC contact(s) of the recept. are connected

406.3 D,1 points to that too. But I don't know what you mean by 5" box. Is that a 4 and 11/16" ?

 

[Sierrasparky]

If this is a metal box that has the EGC bonded to it, wouldn't a regular receptacle with the plastic washers removed and metal to metal ( yoke to box) be okay?

Why is that the way you have been doing it. You need to use those receps with the brass clip and are considered self grounding. for this purpose.

 

[Sir String]

...But I don't know what you mean by 5" box. Is that a 4 and 11/16" ?

Yes, of course.

 

[infinity]

I'd go with406.3(C)
But I don't know what you mean by 5" box. Is that a 4 and 11/16" ?

5" box is slang for a 4 11/16" boxes.


Also take a look at 250.146, 250.146(B) and 250.148(B).

 

[jumper]

Why is that the way you have been doing it. You need to use those receps with the brass clip and are considered self grounding. for this purpose.

No, I am a "bondaholic", I use self grounding receptacles and attach a pigtail.

 

[jumper]

5" box is slang for a 4 11/16" boxes.


Also take a look at 250.146, 250.146(B) and 250.148(B).

250.146 is what I was referring to

Say I used MC in the following picture and bonded the box with the EGC, Do I still need self grounding receptacles?

 

[George Stolz]

If the device yoke is in contact with the box, then that's right.

 

[Sierrasparky]

If the device yoke is in contact with the box, then that's right.

I alwas thought you needed those self grounders!

 

[infinity]

250.146 is what I was referring to

Say I used MC in the following picture and bonded the box with the EGC, Do I still need self grounding receptacles?

That graphic is box specific since it's surface mounted. So in answer to your question you would not need a bonding jumper if the box were grounded and at least one of the insulating washer on the 6-32 were removed.

 

[George Stolz]

I alwas thought you needed those self grounders!

For a flush-mounted receptacle, yes. See 250.146(B), and here's what the UL White book says:

Self-grounding Receptacles ? Self-grounding receptacles have special integral means for establishing the grounding circuit between device yokes and (1) the grounded metallic ?ush-type boxes, or (2) the grounded nonme-tallic ?ush device boxes employing a grounding strap and terminal; without the use of bonding jumpers as permitted by Section 250.146(B) (formerly Exception No. 2 to Section 250-74) of the NEC. These devices are identi?ed by the statement: ``This receptacle is Listed by Underwriters Laboratories Inc. and has a special pressure spring clip to establish the grounding circuit between device yokes and (1) the grounded metallic ?ush-type boxes, or (2) the grounded nonmetallic ?ush device boxes employing a grounding strap and terminal; without the use of bonding jumpers as permitted by Section 250.146(B) of the National Electrical Code'' (or equivalent wording) which may appear on the device or shipping carton.

 

[jumper]

Anyone know when self grounding receptacles first became available?