I would like to get several recommendations from experienced electricians on a grounding question I have. I built a new house several years ago and while being built had a subpanel put on backside of my house to feed future shop build. My shop is now built and I ran two 2 inch underground conduits from house subpanel to shop which is 75 feet away. In one conduit I ran tv coax, Ethernet cable for computer and wire for security. In other conduit I ran 2 electrical circuits to shop, one for overhead LED lights and one for electrical outlets. These circuits run straight to fixtures or plugs with no panel in shop. The only ground wire installed today is the one in my garage at main house panel that sub-panel feeds out of. What do I need to do for additional grounding for shop circuits?? I was also told by someone being my shop is a red-iron frame that I need to drive a ground rod somewhere outside shop and attach a ground wire to someplace on one of the frame pieces??? Would like to get some good advice on what to do. I am not a electrician with the knowledge that many of you have so please remember that in your response. Thanks!!
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Please help with Grounding question!!
- Thread starter mgnic
- Start date
sberry
Banned
The ground wire should also be bonded to the building frame.
wyliesdiesels
Well-known member
U need to abandoned one of the feeds.
The bond to the building steel connects to the EGC in the feeder.
NEC doesnt require electrodes for a single branch circuit feeder.
The bond to the building steel connects to the EGC in the feeder.
NEC doesnt require electrodes for a single branch circuit feeder.
teamextreme
Well-known member
U need to abandoned one of the feeds.
The bond to the building steel connects to the EGC in the feeder.
NEC doesnt require electrodes for a single branch circuit feeder.
Doesn't 2 circuits set up as a MWBC (fed from 2 pole breaker, etc) constitute a "single" circuit for the purposes of this discussion, which would make this setup ok (provided he adds the building steel bond)? I believe he would also need a double pole switch at the entrance of the wires to the shop to act as a disconnect.
NEC 250.104 (3)(C) requires exposed structural metal building frame that is not intentionally grounded supplied by a feeder or branch circuit is required to be bonded to:
• Service enclosure
• Grounded conductor at service
• Disconnecting means supplied by a feeder or ONE branch circuit (2 is a no-no)
• Grounding electrode conductor or
• Grounding electrodes
If the grounding electrode conductor is of sufficient size. The minimum size in table 250.102(C) is #8 Cu. And then we get into upsizing it for protection from physical damage.
Great excuse to put in that subpanel you always wanted.
• Service enclosure
• Grounded conductor at service
• Disconnecting means supplied by a feeder or ONE branch circuit (2 is a no-no)
• Grounding electrode conductor or
• Grounding electrodes
If the grounding electrode conductor is of sufficient size. The minimum size in table 250.102(C) is #8 Cu. And then we get into upsizing it for protection from physical damage.
Great excuse to put in that subpanel you always wanted.
Doesn't 2 circuits set up as a MWBC (fed from 2 pole breaker, etc) constitute a "single" circuit for the purposes of this discussion, which would make this setup ok (provided he adds the building steel bond)? I believe he would also need a double pole switch at the entrance of the wires to the shop to act as a disconnect.
It really depends if one or two neutrals were used, if two then is non compliant.
wyliesdiesels
Well-known member
Doesn't 2 circuits set up as a MWBC (fed from 2 pole breaker, etc) constitute a "single" circuit for the purposes of this discussion, which would make this setup ok (provided he adds the building steel bond)? I believe he would also need a double pole switch at the entrance of the wires to the shop to act as a disconnect.
A MWBC is considered by code as 1 circuit containing 2 hots 1 neutral, 1 EGC.
According to the OP, he ran 2 separate circuits meaning 2 separate hots, 2 separate neutrals, 2 separate EGCs, so this is NOT an MWBC.
One need to be abandoned.
ard
Well-known member
The only ground wire installed today is the one in my garage at main house panel that sub-panel feeds out of.
Quite a sentence.... Anyone else tripping over this?
teamextreme
Well-known member
It really depends if one or two neutrals were used, if two then is non compliant.
True, I guess that was what my "etc" implied.
A MWBC is considered by code as 1 circuit containing 2 hots 1 neutral, 1 EGC.
According to the OP, he ran 2 separate circuits meaning 2 separate hots, 2 separate neutrals, 2 separate EGCs, so this is NOT an MWBC.
One need to be abandoned.
Except he hasn't specifically stated how many neutrals are ran. If there are "2" breakers feeding the shop, most people would refer to that as 2 circuits, even if there is indeed only one neutral shared between them, making it a MWBC and therefore wouldn't require the grounding electrodes.
wyliesdiesels
Well-known member
Quite a sentence.... Anyone else tripping over this?
I think he was referring to the GEC.
Although the 2 individual ckts or multi-wire circuit uncertainty provide some questions and compliance issues all by themselves, the size of the bonding jumper from the exposed steel framing has to be #8 Cu minimum per 250.102 (C)(1).
Short of installing a sub-panel in the shop, the OP will need a disconnecting means for the one feed/(multi-wire/single) branch circuit. The disconnect location will be the point of connection for his required #8 min bonding wire.
Short of installing a sub-panel in the shop, the OP will need a disconnecting means for the one feed/(multi-wire/single) branch circuit. The disconnect location will be the point of connection for his required #8 min bonding wire.