I have never installed an overhead 320amp service. All the 320amp services I have installed have been underground. I have the service mast needing to be 2 1/2" rigid pipe. With the wires for the service mast at 400kcmil copper conductors. Could I reduce the size of the neutral? Did I get it all wrong? They are planning to increase the load on house with a future swim pool and jacuzzi, and possibly more, so I figured to do the wiring at the whole 320amps.
320amp residential overhead service
- Thread starter difowler1
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mopowr steve
Senior Member
- Location
- NW Ohio
- Occupation
- Electrical contractor
Seems a little off,
3” conduit with 3-500mcm copper I believe what is needed and yes you could reduce neutral which may take you back to 2 1/2”
Unless you have load calculations which would prove otherwise.
3” conduit with 3-500mcm copper I believe what is needed and yes you could reduce neutral which may take you back to 2 1/2”
Unless you have load calculations which would prove otherwise.
jumper
Senior Member
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- 3 Hr 2 Min from Winged Horses
500kcmil is correct but jeez 400kcmil is only off by 3 amps.
dbailey0521
Member
- Location
- Crystal River, FL, USA
I just installed one today for a commercial building. 2 - 500 MCM CU and 1 - 350 MCM CU in a 2 1/2" rigid riser. Split out to 2 200 amp disconnects. One was back to back and one extended.
320amp overhead service
320amp overhead service
Are you using the 60 degree Celsius column of 310.15(b)(16) to get the 500mcm? On 310-15(b)(7) (single phase dwelling services and feeders) for residential you can reduce the size of the wire to 83% of the service rating. So using that 60 degree column at 83%, I could use 300mcm?
320amp overhead service
Are you using the 60 degree Celsius column of 310.15(b)(16) to get the 500mcm? On 310-15(b)(7) (single phase dwelling services and feeders) for residential you can reduce the size of the wire to 83% of the service rating. So using that 60 degree column at 83%, I could use 300mcm?
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
If you are using 2 200 amp panels, the wire in the riser can be "what ever you want" (sized to load) and doesn't need to be a full 400 amps.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
No, I spaced out.
400kcmil is good for 335A. The load is 400A, so 400A x .83 = 332A.
You are over by 3A, not short. My bad.
jeff48356
Senior Member
- Location
- Livonia, Michigan
I've never installed anything larger than a 200A service. What would a 320A service with two 200A panels cost the customer, on average, compared to a single 200A service. Let's say, for example, a 200A runs $1500 complete.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
The 320 sockets are a big price jump. Here they are around $320, and they dont come with lugs.
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