When you have an old school 10-30 or 10-50 receptacle (3 wire, 120/240V, no separate grounding conductor), is there a requirement to bond the metal box? Is the neutral terminal on these receptacle in contact with the mounting strap, so the box gets grounded that way? Does something in article 250 cover this?
Bonding old 10-x receptacle boxes
- Thread starter suemarkp
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LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Yes, usually (but the box is supposed to be directly connected to the EGC* itself), and yes.
*The old provisions for bonding to the neutral on 3-wire appliance circuits include boxes, etc.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
By the way, when I saw the 10-x in the title, my mind immediately went to X-10 technology. 
These have no EGC. Think 3 insulated conductor NM cable with no ground wire. These are the old type dryer and range circuits before the 4 wire circuit was mandated in new construction. Im thinking you treat these as an ungrounded branch circuit like 1960s and prior.
Im thinking Larry answered the question stating the neutral is used to bond the box.
Im thinking Larry answered the question stating the neutral is used to bond the box.
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