grd rod

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enireh

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Canyon Lake,TX
I'm on a lot of properties that have out buildings with sub panels 100' or more where it is not posssible or economical for the owner to make it a four wire system instead of three wire. I've shown the info on grounding and most say they are fine with what they have. Would driving a ground rod at a sub panel that is a three wire feed be ok and if so, would I separate the grd and neutral bar at that sub panel so the ground bar is tied to the ground rod and neutral tied to the source?
 
ActionDave said:
No, you leave the neutrals and the grounds bonded or there is no safe way to clear a fault. Before 2005 we did this a lot. As long as there is not another metallic path between the structures like a water line it's safe.
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Or water pipe, gas pipe, CATV, telephone, or any other metallic pipe or wire/cable.
 
Existing feeder can be left that way if it meets all the conditions.

If new construction and they can't afford the extra conductor - they probably can't afford to build in the first place, depending on what you are supplying we have other code changes over the years that probably also have increased what it will cost, especially if dealing with dwelling units.

You can get around needing a separate grounded and grounding conductor by installing a separately derived system at each building. But that might cost more then installing an EGC with the feeder.

Whatever you do DO NOT USE THE EARTH AS THE EGC PATH BACK TO THE SOURCE. If you do make sure you have good liability insurance, though that only protects you financially, you still have to live with the fact your actions got someone electrocuted.
 
electrofelon said:
Another way around it is to use 230.40 Exception #3.
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I guess if that can apply. In that case they would be service conductors and not feeders.

The key to that exception is you can run a dwelling and accessory building from the same service drop, lateral, etc.

Nothing otherwise prevents you from running multiple overhead or underground service conductors to separate buildings on same premises, you just can't feed more then one set of service entrance conductors from any one individual drop, lateral, etc. One set can supply six service disconnecting means though, plus allowed exceptions that would exceed six.
 
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