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Underground service outbuilding and house. 3wire or 4wire?

Underground service outbuilding and house. 3wire or 4wire?

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  #1  
Old 03-08-13, 07:28 AM
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Underground service outbuilding and house. 3wire or 4wire?

Residential Property new 200 amp Electrical Service.
Service to feed from here (2) Underground 100 amp
a Garage 200' away with 100amp panel with Main Breaker / 20 circuit
a House 450' away with 100amp panel with Main Breaker / 20 circuit.

1] Overhead service from street to pole on property...
2]service enters a 200amp combo meter enclosure with 200amp Main
Disconnect (circuit breaker)
3] In same enclosure after 200amp main disconnect via bus are
(2) 100amp 2pole circuit breakers
4] #2 Aluminum to Garage at 200' away
5] 4/0 Aluminum to House at 450' away
My Question is... Can I use 3-wire or do I need 4-wire to each building ?
I will have driven ground rods in each location .. at 200amp meter / disconnect at pole ...
driven ground rods at each / separate Garage and House.
Ive gotten a couple of different answers from electricians so im really confused.. any Help would be Greatly appreciated.. tried reading electrical code book and that left me with my head swimming .. and nightmares ..
 
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  #2  
Old 03-08-13, 07:51 AM
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All panels after the first over current protection device (OCPD) require separate ground and neutral with a bonded ground bar and isolated neutral bar so yes you must have four wires because the panel on the pole is your first OCPD. The subpanels will also require two ground rods.

Ive gotten a couple of different answers from electricians so im really confused
Once up on a time three wire was acceptable if there were no other metallic pathways but that changed at least a couple of national code cycles ago but of course the only way to know for sure is check with the AHJ (Authority Having Jurisdiction). Safety wise four wire is safer for subpanels even if not required. Note the ground and neutral are combined at the first OCPD.
 

Last edited by ray2047; 03-09-13 at 07:38 AM. Reason: Clarification.
  #3  
Old 03-09-13, 04:33 AM
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Thank You , I really appreciate You taking Your time to answer this question for me..
Much appreciated... Rick M.
 
  #4  
Old 03-09-13, 07:27 AM
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Please come back with any more questions as your work proceeds.

I may have been a bit unclear in my answer. To clarify: Neutral and ground are connected at the first panel with the first OCPD but that is the only place
 
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