mansourman
New User
- Location
- texas
- Occupation
- construction
Hey guys- enjoy reading all the debate and knowledge sharing over the years. 1st post. I have a project where the home is 1250' from the service connection. I have talked the provider into a 480/1 er (2) 240/1 feeds to overcome voltage drop. We are putting in a 400amp panel at the house but simultaneous loads aren't expected to peak past 90amps- more than likely 78 amps. We have SER cable in 4" pvc conduit underground run 1250'. The cable is (4) 250 MCM with 4/0 ground. I know- huge. I've debated the 240v vs 480v with our ME quite a bit. The house will have a pool, well water, heat pumps, 1 electric 5kw water heater, electric oven, dryer, and about about 9 tons a/c- I think 20 SEER- 4400 sft. High efficiency stuff variable speed compressors ect - but a lot of it.
I'm thinking each feed holds half of the amp draw- (2) 250 MCM conductors per feeder. The utility provider is providing 480/1 which is really (2) 240/1 feeders. To be safe we are aiming at 125 amps at the house. So if I'm understanding the equations thats 75 amps running down each feeder at 240v giving a total of 150amps to the house. Likely the total distance run to the wall outlet would be another 150'- so worse case 1400'. If my assumptions are good as stated above I'm seeing roughly 3.5% voltage drop total per feeder of (2) 250 mcm 240v 75 amps? 1st question are my assumptions above right?
2nd question: Do we really need a the 480/1 to (2) 240v from the utility provider to our 480v/1 to 240v/120 xfmr of our own? If we just ran 240/1 or (2) 120v feeds and I'm calculating correctly I'm seeing 6.9% voltage drop at 150 amps on a 120v dual feed- (2) 250 mcm at 120v each @ 62.5amps. Are these numbers right? Is 6.9% total drop too much?
Thanks guys- Chris
I'm thinking each feed holds half of the amp draw- (2) 250 MCM conductors per feeder. The utility provider is providing 480/1 which is really (2) 240/1 feeders. To be safe we are aiming at 125 amps at the house. So if I'm understanding the equations thats 75 amps running down each feeder at 240v giving a total of 150amps to the house. Likely the total distance run to the wall outlet would be another 150'- so worse case 1400'. If my assumptions are good as stated above I'm seeing roughly 3.5% voltage drop total per feeder of (2) 250 mcm 240v 75 amps? 1st question are my assumptions above right?
2nd question: Do we really need a the 480/1 to (2) 240v from the utility provider to our 480v/1 to 240v/120 xfmr of our own? If we just ran 240/1 or (2) 120v feeds and I'm calculating correctly I'm seeing 6.9% voltage drop at 150 amps on a 120v dual feed- (2) 250 mcm at 120v each @ 62.5amps. Are these numbers right? Is 6.9% total drop too much?
Thanks guys- Chris
