Grounding outlet and switch box

mbrooke

Senior Member
If a device is self grounding, do you still need to bond to the metallic box assuming the ground is terminated on the device?
 

PaulMmn

Senior Member
Just testing my knowledge---> I'd say yes, because removing the device will break the ground continuity, leaving the box ungrounded. <-- this answer may be wrong!!
 

Little Bill

Moderator
Staff member
If a device is self grounding, do you still need to bond to the metallic box assuming the ground is terminated on the device?
The box has to be bonded first, then a jumper to the device. In your case, the jumper isn't required since the device is self-grounded. You can also, in many cases, remove one of the washers on the mounting screws and not use the jumper.
 

mbrooke

Senior Member
I learned something new today. My thinking has always been along the line of Paul's, but code got me asking. Hope it doesn't change.
 

hbiss

EC, Westchester, New York NEC: 2014
I learned something new today. My thinking has always been along the line of Paul's, but code got me asking. Hope it doesn't change.
Remember that hopefully you will remove any plugs from the receptacle before removing it from the box. So at that point the ground is not doing anything.

-Hal
 

mbrooke

Senior Member
Remember that hopefully you will remove any plugs from the receptacle before removing it from the box. So at that point the ground is not doing anything.

-Hal
Oh, trust me, I haven't yet gotten to that point mentally :lol:
 

PaulMmn

Senior Member
Remember that hopefully you will remove any plugs from the receptacle before removing it from the box. So at that point the ground is not doing anything.

-Hal
Where else would you plug in the drop light to illuminate your work? :lol:
 

LarryFine

Master Electrician Electric Contractor Richmond VA
The rule is that it's the box that must be grounded; the device grounding is what's eliminated by the self-grounding feature. In other words, the feature is for grounding of the device, not the box.
 

ramsy

Senior Member
..You can also, in many cases, remove one of the washers on the mounting screws and not use the jumper.
Just because permits with inspections regularly pass re-modelers, rope pullers, and general contractors that fire any helper using device-grounding terminals, KO seals, or who pull drywall rocks from boxes, does not mean it will pass an insurance claim.

If device is not self bonding, violating the device listing or 110.3(B) gives freebees to the insurance industry, who find listing violations as cause for denying casualty claims.
 

Little Bill

Moderator
Staff member
.
Just because permits with inspections regularly pass re-modelers, rope pullers, and general contractors that fire any helper using device-grounding terminals, KO seals, or who pull drywall rocks from boxes, does not mean it will pass an insurance claim.

If device is not self bonding, violating the device listing or 110.3(B) gives freebees to the insurance industry, who find listing violations as cause for denying casualty claims.
What are you talking about?

(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
 

infinity

Moderator
Staff member
As Bill pointed out there is one instance where you can remove a single insulating washer to bond the receptacle and that when using a surface FS style box like one of these:
 

kwired

Electron manager
FS boxes are not the only limitation when it comes to "surface mounted".

I almost never use a bonding jumper to devices on other types of metallic surface mounted boxes, even cover mounted devices can be bonded through the cover if the cover is of a type allowed to do so. (typical 4x4 raised cover)
 

infinity

Moderator
Staff member
FS boxes are not the only limitation when it comes to "surface mounted".

I almost never use a bonding jumper to devices on other types of metallic surface mounted boxes, even cover mounted devices can be bonded through the cover if the cover is of a type allowed to do so. (typical 4x4 raised cover)
I agree that's true but that is not what Bill was referencing, he specifically mentioned removing the insulating washer from behind the 6-32 mounting screw for the purpose of metal to metal contact between the box and the yoke. That wouldn't really apply to cover mounted boxes.

Besides FS and variants of that type of box what other types of surface mounted boxes are you thinking about?
 

kwired

Electron manager
I agree that's true but that is not what Bill was referencing, he specifically mentioned removing the insulating washer from behind the 6-32 mounting screw for the purpose of metal to metal contact between the box and the yoke. That wouldn't really apply to cover mounted boxes.

Besides FS and variants of that type of box what other types of surface mounted boxes are you thinking about?
I guess I don't know exactly what FS is, but many refer to those like you pictured that are typically water resistant to at least some degree. Simple "handybox" or 4x4 with raised covers are also pretty commonly found surface mounted.

I think your post could be interpreted by some that only those weatherproof boxes like you posted a picture of are allowed to not utilize a bonding jumper to the device, may or may not be what you intended though.

Add: my comment wasn't addressing removing screw retaining non metallic washers as much as it was addressing the need to require a wire bonding jumper, or not.
 

infinity

Moderator
Staff member
I guess I don't know exactly what FS is, but many refer to those like you pictured that are typically water resistant to at least some degree. Simple "handybox" or 4x4 with raised covers are also pretty commonly found surface mounted.

I think your post could be interpreted by some that only those weatherproof boxes like you posted a picture of are allowed to not utilize a bonding jumper to the device, may or may not be what you intended though.

Add: my comment wasn't addressing removing screw retaining non metallic washers as much as it was addressing the need to require a wire bonding jumper, or not.
Got it. In my original post I said "FS like boxes" not thinking that FS wasn't common terminology.

You're correct a handy box would be another type of box (not similar to an FS) where removing the washer to provide the bonding would be permitted. :cool:
 

romex jockey

Senior Member
.

What are you talking about?

(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
yup...250.146B Bill

~RJ~
 

ramsy

Senior Member
(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)..
Thanks Bill.

Strange that flush-mount metallic boxes are excluded.
 
Thanks Bill.

Strange that flush-mount metallic boxes are excluded.
I've justified that it applies to surface and not flush because with flush mount, there's a chance that the yoke isn't tight up against the box because of drywall/plaster and therefor not making solid metal to metal contact between yoke and box. With self-grounding receptacles that wouldn't be a problem so only they are ok for flush without the jumper. No?
 

PaulMmn

Senior Member
Let's see... the mounting screw for the duplex outlet goes through the mounting strap and into the hole in the box. The head of the screw, with or without the "don't lose the screw" washer, makes contract with the strap. The threads of the screw make good, solid contact with the box. Now, please explain how removing one of the "don't lose the screw" washers improves conductivity??
 

infinity

Moderator
Staff member
Let's see... the mounting screw for the duplex outlet goes through the mounting strap and into the hole in the box. The head of the screw, with or without the "don't lose the screw" washer, makes contract with the strap. The threads of the screw make good, solid contact with the box. Now, please explain how removing one of the "don't lose the screw" washers improves conductivity??
Because it allows the yoke to make direct contact with the box when using a surface mounted box.
 

ramsy

Senior Member
..with flush mount, there's a chance that the yoke isn't tight up against the box because of drywall/plaster and therefor not making solid metal to metal contact between yoke and box..
Yes, that makes sense.
 

nickelec

Senior Member
Here in NYC inspectors want to see the Bonding jumper from box to device even with self ground devices
even though the whole Installation is metallic I can't seem to locate in the NYC amendments where it's required

Sent from my SM-G965U using Tapatalk
 

infinity

Moderator
Staff member
Here in NYC inspectors want to see the Bonding jumper from box to device even with self ground devices
even though the whole Installation is metallic I can't seem to locate in the NYC amendments where it's required

Sent from my SM-G965U using Tapatalk
Not sure why you're seeing that because it is not required. We have been using MC-ap for years with self-grounding receptacles and never install a bonding jumper to the box. Here are all of the NYC electrical code amendments for Article 250:

NYC 2011 Electrical Code Technical Provisions

ARTICLE 250
Grounding and Bonding
SECTION 250.52
Subsection 250.52(A)(1) – Delete the Exception in its entirety.
 

kwired

Electron manager
Let's see... the mounting screw for the duplex outlet goes through the mounting strap and into the hole in the box. The head of the screw, with or without the "don't lose the screw" washer, makes contract with the strap. The threads of the screw make good, solid contact with the box. Now, please explain how removing one of the "don't lose the screw" washers improves conductivity??
Though I never did this with receptacles, which also need to pass the EGC onto whatever is plugged into them, I have taken this approach before with switches and had inspector shoot it down even though it sort of doesn't make any sense. But I somewhat reluctantly changed it because wording in code says what it says.
 

mbrooke

Senior Member
Not sure why you're seeing that because it is not required. We have been using MC-ap for years with self-grounding receptacles and never install a bonding jumper to the box. Here are all of the NYC electrical code amendments for Article 250:
Is NYC still on the 2011 modified code?
 
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