I'm doing a "grounding and bonding" continuing education online class and this is one of the questions. It is claiming that a ground screw is not needed in a metal box if you remove one or more of the fiber retention washers and the metal yoke of the receptacle is in direct contact of the metal box. Is this true or am I interpreting this wrong?
Does a handy box need a ground screw? (250.146 (a))
- Thread starter crtemp
- Start date
- Status
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
I would say yes only if the receptacle or other device is listed as self grounding.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
If you're referring to a receptacle with a bonding jumper and a ground screw you are correct, with a surface mounted handy box neither is required if at least one washer is removed. A self-grounding receptacle is not required either.
fmtjfw
Senior Member
- Location
- Fairmont, WV, USA
NO, someone is reading the Code backwards.
NO, someone is reading the Code backwards.
and skipping explicit text.
250.146 Connecting Receptacle Grounding Terminal to Box.
....
(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.
>>>bonding receptacle TO the box, not the box to the receptacle.
(B) Contact Devices or Yokes. Contact devices or yokes designed and listed as self-grounding shall be permitted in conjunction with the supporting screws to establish equipment bonding between the device yoke and flush-type boxes.
>>>This may be leading people astray.
250.148 Continuity and Attachment of Equipment Grounding Conductors to Boxes.
....
(B) Grounding Continuity. The arrangement of grounding connections shall be such that the disconnection or the
removal of a receptacle, luminaire, or other device fed from the box does not interfere with or interrupt the grounding continuity.
>>> you remove the grounded receptacle and you remove the grounding of the box!
(C) Metal Boxes. A connection shall be made between the one or more equipment grounding conductors and a metal box by means of a grounding screw that shall be used for no other purpose, equipment listed for grounding, or a listed grounding device.
>>> the EGC must be connected to the box
NO, someone is reading the Code backwards.
and skipping explicit text.
250.146 Connecting Receptacle Grounding Terminal to Box.
....
(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.
>>>bonding receptacle TO the box, not the box to the receptacle.
(B) Contact Devices or Yokes. Contact devices or yokes designed and listed as self-grounding shall be permitted in conjunction with the supporting screws to establish equipment bonding between the device yoke and flush-type boxes.
>>>This may be leading people astray.
250.148 Continuity and Attachment of Equipment Grounding Conductors to Boxes.
....
(B) Grounding Continuity. The arrangement of grounding connections shall be such that the disconnection or the
removal of a receptacle, luminaire, or other device fed from the box does not interfere with or interrupt the grounding continuity.
>>> you remove the grounded receptacle and you remove the grounding of the box!
(C) Metal Boxes. A connection shall be made between the one or more equipment grounding conductors and a metal box by means of a grounding screw that shall be used for no other purpose, equipment listed for grounding, or a listed grounding device.
>>> the EGC must be connected to the box
mjf
Senior Member
I'm under the impression that you correctly answered what the OP asked and the other posters correctly answered what the OP MEANT TO ASK.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
The OP never mentioned a wire type EGC in this surface mounted box only that it's metallic. So if the metal box is already properly grounded then the receptacle only needs one washer removed to complete the grounding path.
mjf
Senior Member
Agree, but the OP really wasn't clear with his "scenario".
I believe the OP is referring to the ground screw on the device, yet, he said "ground screw in a metal BOX"
QUOTE: "It is claiming that a ground screw is not needed in a metal box if you remove one or more of the fiber retention washers and the metal yoke of the receptacle is in direct contact of the metal box."
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- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Yes, it mean the device ground screw if mounted in a metal box or it could mean the ground screw for the box itself if the device ground terminal is attached.
mopowr steve
Senior Member
- Location
- NW Ohio
- Occupation
- Electrical contractor
Yes, no matter what a metal box must be properly grounded first a foremost either by metallic connection to metal raceway or via ground wire attached to ground screw in-side box then you can apply the various methods to ground your device.
Makes sense to me now. Thanks for all the clarification
- Location
- Massachusetts
No one should use a handy box for a device anyway. Problem solved. :thumbsup:
electricman2
Senior Member
- Location
- North Carolina
- Occupation
- Retired Electrical Contractor
mopowr steve
Senior Member
- Location
- NW Ohio
- Occupation
- Electrical contractor
Bingo!
Agree, if you're using 12awg conductors it's likely that box fill calculation will not allow for a device to be installed in that handybox.
What is the big deal with using a handy box? I always use them behind built in microwaves with trim kits? As long as there is only one wire in it I don't see any issues
- Location
- Massachusetts
I would use a 4" square with a raised cover for that. Code compliant or not I see no reason to make life harder on myself trying to jam a device into handy box.
For what it's worth a standard handy box is 13.0 cu in. allowing six 14s or five 12s.
mopowr steve
Senior Member
- Location
- NW Ohio
- Occupation
- Electrical contractor
For #12's
1- hot conductor
1- neutral conductor
1- grounds
1- connector/cable clamp
2- device
6allowances x 2.25cu/in per @ #12s = 13.5cu/in of box fill volume required
POOP!
I know, got shot down once by inspector in the 90's on a cinder block wall with foam insulation and furring strips on top that just happened to work out in depth for a handy box for receptacles. Ended up changing to 4squares with right depth P-Rings
1- hot conductor
1- neutral conductor
1- grounds
1- connector/cable clamp
2- device
6allowances x 2.25cu/in per @ #12s = 13.5cu/in of box fill volume required
POOP!
I know, got shot down once by inspector in the 90's on a cinder block wall with foam insulation and furring strips on top that just happened to work out in depth for a handy box for receptacles. Ended up changing to 4squares with right depth P-Rings
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thats pretty petty! What do you do if you have a light run in 12-2 that must be in a 3/0 pancake box?
- Location
- Massachusetts
I don't think knowing and following the code is petty, I think professional is a better description.
Don't do it, find another way, another box type, a surface extension, a canopy marked with the cu in. Etc.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Where did you find a handy box with the clamping mechanism on the inside?
fmtjfw
Senior Member
- Location
- Fairmont, WV, USA
- Status