120/240 1ph feeder sizing

[Bill Davis]

I am installing a 320 amp single phase residential service mast. It serves a 200amp and 150 amp disconnect. Can I size to the rating of the 320amp meter socket or do I have to combine the disconnects for for the total of 350 amps?

 

[raider1]

The conductors in the service mast must be sized for the load calculated in accordance with Article 220. Take a look at 230.23.

Chris

 

[iwire]

I am installing a 320 amp single phase residential service mast. It serves a 200amp and 150 amp disconnect. Can I size to the rating of the 320amp meter socket or do I have to combine the disconnects for for the total of 350 amps?

You can size it as small as the calculated load.

If you do not know the calculated load you will have to size it at least as large as combined rating of the over current protection.

By the way, a 320 amp meter is rated 400 amps non-continuous.

 

[acrwc10]

Save some money on wire and do the load calcs. I have seen some large conductors used many times when a much smaller conductor would have work just fine. You may be surprised at what the numbers come up to, houses don't really use much amperage, unless you have a large amount of electric heating, or a very large house.

 

[Dennis Alwon]

I would just install a 400 amp service , ie two 200 amp panels. Heck a 150 amp panel around here is unheard of anyway

 

[Bill Davis]

Yeah, Well the original service was 150 amps and its 120' to the first panel. The new panel to serve new sq. ft., a spa and a swim machine. I probably should have installed another 150 amp panel instead. Got gas heat and water tank, total now of 4466 sq. ft.. I didn't consider the mast conductors until my trencher fell into a cave in the front yard. The power co. was to furnish the conductors. Now it could be months before sewer and drain get around to repairing a 50 year old storm drain and the people want the project finished.

 

[acrwc10]

Yeah, Well the original service was 150 amps and its 120' to the first panel. The new panel to serve new sq. ft., a spa and a swim machine. I probably should have installed another 150 amp panel instead. Got gas heat and water tank, total now of 4466 sq. ft.. I didn't consider the mast conductors until my trencher fell into a cave in the front yard. The power co. was to furnish the conductors. Now it could be months before sewer and drain get around to repairing a 50 year old storm drain and the people want the project finished.

4466 sq ft is small if you have gas heating. The pump in the swim machine sounds like your largest motor, I'm guessing if you put up the numbers your well under 225 amp load. give us the numbers for the house and lets see where they end up. We have 4466 x 3 VA =13,398 VA for general lighting.
What have you got for Kitchen, laundry, Air cond., etc. ?

 

[Bill Davis]

Thanks, I should have already run the numbers. I didn't think I would get called on 400kcm AL but I did. Now I'll have to go up and inventory all items. Or toss the 400 and replace with 500.