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Old 10-18-2011, 08:15 AM   #1
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Tleeh


I have a 200 amp feed through breaker in my barn and I want to set up another 200 amp feed through breaker 525 ft away. The second panel will never draw more than 50 amps but I already own the second panel and a 200 amp disconnect. My plan is to go underground with a 2-2-2-4 aluminum ser. Will this work?

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Old 10-18-2011, 10:33 AM   #2
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Time for a debate on the FPNs to 215.2(A)(3). For a run that long and assuming 220V single-phase, I think you're going to need to upsize the conductors to 1/0 to meet the 5% voltage drop rule (assuming it's a rule and not a guideline, and using the 5% cutoff instead of 3%). I don't suppose you can get a new 480V service can you?

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Old 10-18-2011, 11:20 AM   #3
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What is the current distance from the barn to the transformer, or house if feeding from the house. If you have a step-up transformer on site, it would be easier to place a panel there, then feed everything from that transformer, than hopping building to building.

http://www.temcoindustrialpower.com/...s#240_standard
http://www.temcotransformer.com/
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Old 10-18-2011, 11:25 AM   #4
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Tleeh


Quote:
Originally Posted by Tleeh View Post
I have a 200 amp feed through breaker in my barn and I want to set up another 200 amp feed through breaker 525 ft away. The second panel will never draw more than 50 amps but I already own the second panel and a 200 amp disconnect. My plan is to go underground with a 2-2-2-4 aluminum ser. Will this work?
Your plan sounds half baked and it doesn't sound like you understand what constitutes a feed.
Your 2-2-2-4 should work with 60 amp service at 525 feet. If your second panel that you own has a 200 amp breaker that is fine but the panel in your barn would get a 60 amp breaker to protect the feed to the second panel.
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Old 10-18-2011, 12:45 PM   #5
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Originally Posted by gatorheel View Post
Time for a debate on the FPNs to 215.2(A)(3). For a run that long and assuming 220V single-phase, I think you're going to need to upsize the conductors to 1/0 to meet the 5% voltage drop rule (assuming it's a rule and not a guideline, and using the 5% cutoff instead of 3%). I don't suppose you can get a new 480V service can you?

Matt
FPNs are not enforceable/code, and 1/0 cannot be protected at 200 amps.

240v is a nominal voltage, not 220v.
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Old 10-18-2011, 01:06 PM   #6
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1/0 cannot be protected at 200 amps.
OP states a 50A load over a 525 foot run. The constraint dictating conductor size is voltage drop, not ampacity. For a 525 foot run, 240V single-phase (switched to nominal from colloquial, hope that makes you feel better) over aluminum is going to drop 7%. Depending on the use, that might be a problem, AHJ enforceable or not.

Matt
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Old 10-18-2011, 01:19 PM   #7
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Quote:
Originally Posted by gatorheel View Post
OP states a 50A load over a 525 foot run. The constraint dictating conductor size is voltage drop, not ampacity. For a 525 foot run, 240V single-phase (switched to nominal from colloquial, hope that makes you feel better) over aluminum is going to drop 7%. Depending on the use, that might be a problem, AHJ enforceable or not.

Matt
Op wanted to use a 200 amp breaker as a feeder breaker, 1/0 will not cut it. 240.4 says no here.

Voltage drop is only addressed as code in 647 and 695, otherwise it is a design issue. Important-yes, code-no.

Ampacity is the key to conductor size.
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Old 10-18-2011, 01:26 PM   #8
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Originally Posted by Code05 View Post
Op wanted to use a 200 amp breaker as a feeder breaker, 1/0 will not cut it. 240.4 says no here.

Voltage drop is only addressed as code in 647 and 695, otherwise it is a design issue. Important-yes, code-no.

Ampacity is the key to conductor size.
Good point. I had a sentence about that (needing a smaller disconnect), but I guess I accidentally cut it out in an edit. I'll agree that ampacity is the key when discussing code, but voltage drop is likely to be the constraint which is key in the overall design of the feeder. For 50A, he could run #6 and save a lot of $s, but I'm pretty sure he wouldn't be happy with 94V (edit: 214V on both legs).

Matt

Last edited by gatorheel; 10-18-2011 at 01:32 PM.
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Old 10-18-2011, 01:26 PM   #9
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Quote:
Originally Posted by gatorheel View Post
OP states a 50A load over a 525 foot run. The constraint dictating conductor size is voltage drop, not ampacity. For a 525 foot run, 240V single-phase (switched to nominal from colloquial, hope that makes you feel better) over aluminum is going to drop 7%. Depending on the use, that might be a problem, AHJ enforceable or not.

Matt
220.5 Calculations.
(A) Voltages. Unless other voltages are specified, for purposes
of calculating branch-circuit and feeder loads, nominal
system voltages of 120, 120/240, 208Y/120, 240, 347,
480Y/277, 480, 600Y/347, and 600 volts shall be used.
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Old 10-18-2011, 01:29 PM   #10
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Good point. I had a sentence about that (needing a smaller disconnect), but I guess I accidentally cut it out in an edit. I'll agree that ampacity is the key when discussing code, but voltage drop is likely to be the constraint which is key in the overall design of the feeder. For 50A, he could run #6 and save a lot of $s, but I'm pretty sure he wouldn't be happy with 94V.

Matt
Ampacity is code. VD is design. Both are needed for a good install. 94v would suck.

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