Sizing Wire

[infinity]

NEC 210.19(A)(1) Informational Note No. 4 limits the voltage drop at the furthest outlet of a load to 3% of the applied voltage. This allows 2% drop in the feeder. Alternatively, the maximum combined voltage drops on the feeder and branch circuits going to the furthest outlet of a load should be limited to 5%.

As Roger stated VD compensation is not mandatory with only a few exceptions in the NEC. Fire Pumps and Article 647 Sensitive Electronic Equipment being two of them.

 

[JonathanWaldner]

As I said earlier, try to consult with a local EE or EC that is experienced with this type of installation. MV work is not forgiving if something does go wrong.

Sorry, but I don't give out my number.

What is the power factor for 7200 volts 480 is 830.4 but I don"t no what it is for 7200

 

[electrofelon]

For this sort of thing you REALLY HAVE TO do some soul searching and figure out what you ACTUAL load will be. ITs very unlikely to be more than half of what your load calc is. You will be throwing tens of thousands of someone's dollars down the toilet if you overestimate actual current draw. Assuming about 75 KVA which is 208 amps at 208 three phase is probably a decent start just for discussion purposes. at 480V, that is 90 amps, and I am showing 2 sets of 350 AL to be adequate. 350 URD quad is $5.95/foot from nassau national cable's website, and it will of course be cheaper than that with a quote and/or shopping around. So lets just say $5.50/ foot/ run so $11 per foot total. That is actually about the cost of 3 runs of 15KV #2 1/3 CN MV cable which i imagine is what you would use for a 15 KV run. Another option to MAYBE look at is using AL 2KV RHHW (PV wire) which is a very competitively priced cable. You would need about a single run of #4/phase. You would need to have 2000V transformers built but you could get a quote from say hammond ermco, or olsun. But likely it looks like just running the 480 is the way to go.

 

[JonathanWaldner]

For this sort of thing you REALLY HAVE TO do some soul searching and figure out what you ACTUAL load will be. ITs very unlikely to be more than half of what your load calc is. You will be throwing tens of thousands of someone's dollars down the toilet if you overestimate actual current draw. Assuming about 75 KVA which is 208 amps at 208 three phase is probably a decent start just for discussion purposes. at 480V, that is 90 amps, and I am showing 2 sets of 350 AL to be adequate. 350 URD quad is $5.95/foot from nassau national cable's website, and it will of course be cheaper than that with a quote and/or shopping around. So lets just say $5.50/ foot/ run so $11 per foot total. That is actually about the cost of 3 runs of 15KV #2 1/3 CN MV cable which i imagine is what you would use for a 15 KV run. Another option to MAYBE look at is using AL 2KV RHHW (PV wire) which is a very competitively priced cable. You would need about a single run of #4/phase. You would need to have 2000V transformers built but you could get a quote from say hammond ermco, or olsun. But likely it looks like just running the 480 is the way to go.

For this sort of thing you REALLY HAVE TO do some soul searching and figure out what you ACTUAL load will be. ITs very unlikely to be more than half of what your load calc is. You will be throwing tens of thousands of someone's dollars down the toilet if you overestimate actual current draw. Assuming about 75 KVA which is 208 amps at 208 three phase is probably a decent start just for discussion purposes. at 480V, that is 90 amps, and I am showing 2 sets of 350 AL to be adequate. 350 URD quad is $5.95/foot from nassau national cable's website, and it will of course be cheaper than that with a quote and/or shopping around. So lets just say $5.50/ foot/ run so $11 per foot total. That is actually about the cost of 3 runs of 15KV #2 1/3 CN MV cable which i imagine is what you would use for a 15 KV run. Another option to MAYBE look at is using AL 2KV RHHW (PV wire) which is a very competitively priced cable. You would need about a single run of #4/phase. You would need to have 2000V transformers built but you could get a quote from say hammond ermco, or olsun. But likely it looks like just running the 480 is the way to go.

So what I am doing is going out of my supply from 480 stepping it up to 7200 cause it around 4000 foot run and at my other end I will step it down to 208/120 and my service that i will put up will be a 400 amp service but I Don't know what wire I should use for it and this is Three Phase and 2 150KVA transformers

 

[augie47]

You seem to getting into an specialized area where you have had little experience and advice we give here might actually place you in a dangerous situation. For that reason I am closing the thread.