House, barn, and outbuilding fed with 3 wire

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maven

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I was looking at a job today at an old farmhouse that has several barns and buildings on the property. The power to the property (120/240v single phase) comes to a pole (in the driveway) with a disconnect mounted at the top of the pole. Hanging on the pole is a rod to open the disconnect. And about 4' off the ground is the meter base.

From this pole disconnect, a 3wire feeder system is ran to a barn breaker panel, the house fuse box panel, and another out building fuse box panel. So there are three separate feeders being spliced together at this disconnect location at the pole to the main feed (from the POCO transformer).

My question: Shouldn't these feeder wires to the house, barn, and outbuilding be a 4 wire system and therefore keep the grounds and neutrals separate at each location? Or does this fall under 250.32B Exception 1,2,3?

If so, does this mean that any detached building can be fed with a 3wire system if it meets 250.32B and exceptions 1,2,3?

I have always been told that I should always separate the grounds and neutrals AFTER the first means of disconnect...so what do you say?
 
maven said:
I was looking at a job today at an old farmhouse that has several barns and buildings on the property. The power to the property (120/240v single phase) comes to a pole (in the driveway) with a disconnect mounted at the top of the pole. Hanging on the pole is a rod to open the disconnect. And about 4' off the ground is the meter base.

From this pole disconnect, a 3wire feeder system is ran to a barn breaker panel, the house fuse box panel, and another out building fuse box panel. So there are three separate feeders being spliced together at this disconnect location at the pole to the main feed (from the POCO transformer).

My question: Shouldn't these feeder wires to the house, barn, and outbuilding be a 4 wire system and therefore keep the grounds and neutrals separate at each location? Or does this fall under 250.32B Exception 1,2,3?

If so, does this mean that any detached building can be fed with a 3wire system if it meets 250.32B and exceptions 1,2,3?

I have always been told that I should always separate the grounds and neutrals AFTER the first means of disconnect...so what do you say?
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Entirely legal and common instal at the time. We still wire buildings this way if there is no common metallic piping between the buildings.
 
I've often wondered this also.

But somehow I've convinced myself that the disconnect you described is a "distribution switch" not "disconnect" in proper terms.

So how are inspectors handling these? Are they requiring 4wire or not to all the buildings.
 
mopowr steve said:
I've often wondered this also.

But somehow I've convinced myself that the disconnect you described is a "distribution switch" not "disconnect" in proper terms.

So how are inspectors handling these? Are they requiring 4wire or not to all the buildings.
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It is a "site isolating device" and allowed by 547.9(A). 4 wire would be required from the pole top switch to the buildings by 547.9(B)(3)
 
mopowr steve said:
I've often wondered this also.

But somehow I've convinced myself that the disconnect you described is a "distribution switch" not "disconnect" in proper terms.

So how are inspectors handling these? Are they requiring 4wire or not to all the buildings.
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If there is no OCPD associated with the pole top disconnect, then it cannot be a "service disconnect" under the NEC. You have three sets of three wire service conductors, which is perfectly fine. Each building needs a disconnect (breaker panel or fused disconnect) that is listed for use as service equipment and each building needs its own Ground Electrode System. These GESs will not interconnect.
 
mopowr steve said:
I've often wondered this also.

But somehow I've convinced myself that the disconnect you described is a "distribution switch" not "disconnect" in proper terms.

So how are inspectors handling these? Are they requiring 4wire or not to all the buildings.
Click to expand...

This county does not have electrical inspections so no one is complaining. :) I just want to make sure it is right.
 
GoldDigger said:
If there is no OCPD associated with the pole top disconnect, then it cannot be a "service disconnect" under the NEC. You have three sets of three wire service conductors, which is perfectly fine. Each building needs a disconnect (breaker panel or fused disconnect) that is listed for use as service equipment and each building needs its own Ground Electrode System. These GESs will not interconnect.
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I don't know if there is an OCPD in that disconnect box or distribution box. I am going to call the POCO tomorrow and ask. I've just never ran into this before in my career.
 
packersparky said:
It is a "site isolating device" and allowed by 547.9(A). 4 wire would be required from the pole top switch to the buildings by 547.9(B)(3)
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This is cool. I did not know this was in the code book! Thank you! You say 4 wires would be required but I do not see it there in the code??
 
maven said:
This is cool. I did not know this was in the code book! Thank you! You say 4 wires would be required but I do not see it there in the code??
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547.9(B)(3) says the grounding and bonding has to comply with 250.32 and 250.32(B)(1) requires an equipment grounding conductor to be installed to separate buildings.
 
maven said:
I don't know if there is an OCPD in that disconnect box or distribution box. I am going to call the POCO tomorrow and ask. I've just never ran into this before in my career.
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If the customer does not have access to the fuses or breaker, there is a strong argument that the disconnect belongs to POCO and is on their side of the service point. It would then still not be a service disconnect.
(Only POCO can make the determination of where the service point is.)

Sent from my XT1585 using Tapatalk
 
readydave8 said:
What year NEC? Thought that stopped being allowed several code cycles ago
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Not quite sure what the reasoning here is, but I’ve yet to be required 4 wire at any rural distribution where an unfused disconnect or terminal box is located at the meter pole, or anywhere else. New houses are required to be inspected but are connected to the existing distribution. Three wire.

For the most part, farm buildings in this area no longer would be considered Agricultural Buildings but are still exempt from inspection. I have never seen a pole top disconnect.
 
I spoke with an engineer at the POCO. He said that the meter and wire from the TX at the road to the pole top distribution was theirs. But everything else is the homeowners.
He told me that the pole top Dbox is NOT fused and these are (in his opinion)" dangerous". I agree too.
There is no fused disconnect anywhere to the fuse box in the house except for the POCO over current protection (7200v/3amp) And he said that if they were to come out and change this it would cost the homeowner.
So if I update this service, I will put a meter/disconnect combo with over current protection at this pole and run a 4wire over head feeder to the house (80'away).
Thanks for all the help!
 
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