400amp residential service

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uwireme

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I have a customer that wants a 400-amp service for a house he is building. The 400amp service with meter has 2-200 amp breakers then 2-3? pvc conduits run 300 feet to his new home and then going to 2-200 amp disconnect switches outside the home and finely ending up in 2-200amp main lug panels inside the home.
My question is wire, I am planning to run 2-350 and 1-4/0 aluminum URD in each 3? from the main service to the disconnects on the home for voltage drop do I need to run a ground wire? Or can I use the concrete encased electrode at the disconnects? Any input would be appreciated.
 
400 amp service

400 amp service

Under the 2002 code 250.32 (A)(B)(C) deal with the GEC. In my understanding it is a better installation to establish grounding in the new structure (ufer ground) than to bring the 4th wire over in case nuetral was ever lost. Good luck!
 
You both should read 250.32 esp.section (B)(2). There has been much debate on this issue but it is very clear if there is any continuous metallic pathway from the meter to the house then a 4 wire must be run. Metallic pathway may be a phone wire, cable, rmc, etc.
 
Pull a equipment ground

Pull a equipment ground

You should connect your main bonding jumper at the 400 amp service equipment and then run a neutral and equipment ground to each structure. The panels in each structure are sub panels of the 400 amp service and have a separate neutral and ground buss. The grounding electrode system for each structure will be bonded to the ground buss in the sub panel for that building.
 
Sounds like a egc is a good idea. Do you think 2-350s and 1-4/ 0 Al URD wire would be a good size for the 300 foot run? I don?t normally use aluminum wire and was wondering if I can run the #6 gec as per 250.122 with THHN?
 
If you were running the wire size allowed by 310.16---- 3/0 copper than a #6 would be fine . Since you chose to upsize your conductors then you have to upsize your EGC proportionally. Art. 250.122(B)

Check out this FAQ about EGC that explains how to go about this
http://forums.mikeholt.com/showpost.php?p=649545&postcount=27

I think 250mcm would probably be fine. Certainly won't hurt to have 350mcm. Check out this online voltage drop calculator--
http://www.elec-toolbox.com/calculators/voltdrop.htm
 
I just realized -- doesn't this violate the "only one feeder to a structure" rule? Seems like two 200A feeders to me and not one parallel one.
 
suemarkp said:
I just realized -- doesn't this violate the "only one feeder to a structure" rule? Seems like two 200A feeders to me and not one parallel one.
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No, read 320.2 Number of Services. As long as your 1/0 or larger, should be good to go.
 
225.30 Number of Supplies.

This would be the section to apply to this installation.



Someone mentioned parallel conductors.
They are not parallel conductors - 310.4 (end of first paragraph) - parallel (electrically joined at both ends)
 
The only one I may be able to use is 225.30(B)(2) but I haven?t done any calculations on that due to my customer wants 400 amps so I dint think it was necessary its only a 4000 square foot home. Not sure if I can get over 200amps. May be able to use 225.30(A)(4) if he installs an emergency generator?
 
stickboy1375 said:
No, read 320.2 Number of Services. As long as your 1/0 or larger, should be good to go.
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Opps. wrong section... 225.30 would be correct. I have to admit, I have done my share of 320 amp pedestal services and brought in two conduits into the building each feeding a 200 amp panel. But I just don't see how it is legal...:confused:
 
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