Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 05-21-2012, 01:25 PM   #1
Newbie
 
Join Date: May 2012
Posts: 9
Rewards Points: 10
Default

20 amp service to an outbuilding 250 to 300 ft.


20 amp service to an outbuilding 250 to 300 ft.
What size wire do I need?
Is LED lighting safe to use in a barn environment- ie dust and hay?

JStofik is offline   Reply With Quote
Old 05-21-2012, 01:45 PM   #2
Member
 
Join Date: Aug 2011
Posts: 90
Rewards Points: 75
Default

20 amp service to an outbuilding 250 to 300 ft.


The wire size calculator says minimum of #3 for 120v.

brgmgb is offline   Reply With Quote
Old 05-21-2012, 01:53 PM   #3
Licensed Electrician
 
k_buz's Avatar
 
Join Date: Mar 2012
Location: SE Wisconsin
Posts: 4,342
Rewards Points: 2,004
Default

20 amp service to an outbuilding 250 to 300 ft.


That's what it says, but there is no code requiring voltage drop sizing. I would run #8's to the outbuilding, then switch down to #12 for the wiring inside.
k_buz is offline   Reply With Quote
Old 05-21-2012, 05:02 PM   #4
Semi-Pro Electro-Geek
 
Join Date: Jul 2009
Location: Arizona, USA
Posts: 2,559
Rewards Points: 2,014
Default

20 amp service to an outbuilding 250 to 300 ft.


What is the actual load? For that long of a run, you might be better off running #10 or #12 wire at 240V, with a transformer at the far end for 120V. This save copper, at the expense of using a transformer. The exact nature of the load will be important.

And yes, LEDs are fine in a barn environment.
mpoulton is offline   Reply With Quote
Old 05-21-2012, 05:32 PM   #5
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Rewards Points: 2,000
Default

20 amp service to an outbuilding 250 to 300 ft.


Quote:
Originally Posted by k_buz View Post
I would run #8's to the outbuilding
A 7v drop at 20A. Maybe use a buck-boost transformer in the boost mode at the destination end. That way the xformer only has to handle 140 VA.

Hay ignites at 170C and LEDs run much cooler than this.

Last edited by Yoyizit; 05-21-2012 at 05:36 PM.
Yoyizit is offline   Reply With Quote
Old 05-21-2012, 06:10 PM   #6
Semi-Pro Electro-Geek
 
Join Date: Jul 2009
Location: Arizona, USA
Posts: 2,559
Rewards Points: 2,014
Default

20 amp service to an outbuilding 250 to 300 ft.


Quote:
Originally Posted by Yoyizit View Post
Maybe use a buck-boost transformer in the boost mode at the destination end.
Have to be very careful with this. It's a great solution if the load is lighting only and always constant. But if there is any variation in the load this will result in unacceptably high voltage when the load is minimal.
mpoulton is offline   Reply With Quote
Old 05-21-2012, 06:12 PM   #7
Licensed Electrician
 
k_buz's Avatar
 
Join Date: Mar 2012
Location: SE Wisconsin
Posts: 4,342
Rewards Points: 2,004
Default

20 amp service to an outbuilding 250 to 300 ft.


I wouldn't think twice about a 7V voltage drop.
k_buz is offline   Reply With Quote
Old 05-21-2012, 06:51 PM   #8
Member
 
Join Date: Oct 2010
Location: Cairns Australia
Posts: 2,656
Rewards Points: 2,272
Default

20 amp service to an outbuilding 250 to 300 ft.


To minimise losses on the long feed line,
I would use a bigger gauge of wire.
I would use 6# for the main feeder line.
Then around the building you can use smaller 8#.
dmxtothemax is offline   Reply With Quote
Old 05-22-2012, 12:23 PM   #9
Newbie
 
Join Date: May 2012
Posts: 9
Rewards Points: 10
Default

20 amp service to an outbuilding 250 to 300 ft.


Thanks to all for responses.
The building will have 3 or 4 lights and 3 small horse bucket heaters and 1 utility receptacle

Based on your feedback, I think I will go with #8 copper 120v and #12 after entrance to feeder box.
JStofik is offline   Reply With Quote
Old 05-22-2012, 01:15 PM   #10
Member
 
kevinp22's Avatar
 
Join Date: Sep 2010
Location: Saint Louis, MO
Posts: 323
Rewards Points: 250
Default

20 amp service to an outbuilding 250 to 300 ft.


for that distance I would do a little future proofing and run #6
kevinp22 is offline   Reply With Quote
Old 05-23-2012, 01:42 PM   #11
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Rewards Points: 2,000
Default

20 amp service to an outbuilding 250 to 300 ft.


Quote:
Originally Posted by mpoulton View Post
Have to be very careful with this. It's a great solution if the load is lighting only and always constant. But if there is any variation in the load this will result in unacceptably high voltage when the load is minimal.
Yes, you have to get a xformer with good regulation such that at zero load you're maybe +10% above nominal value and at 20A you're at -10%.

PoCo's xformer is right outside my house so a 20A load drops the 240V by 0.4V measured at the panel so that's probably the best regulation you can reasonably expect.

CFLs or LED lighting may not be nearly as sensitive to overvoltage as incands.
Yoyizit is offline   Reply With Quote
Old 05-23-2012, 01:49 PM   #12
Member
 
Join Date: Jan 2012
Location: IL
Posts: 823
Rewards Points: 698
Default

20 amp service to an outbuilding 250 to 300 ft.


Quote:
Originally Posted by JStofik View Post
Thanks to all for responses.
The building will have 3 or 4 lights and 3 small horse bucket heaters and 1 utility receptacle

Based on your feedback, I think I will go with #8 copper 120v and #12 after entrance to feeder box.

Why not use 240V heaters? They are likely the dominant current draw in your load. By going 240 you'll cut current in half and can probably go with 15A branch circuit. You'd have to run three conductors plus ground so that offsets some of the benefit of the smaller gauge wire but still probably better.

curiousB is online now   Reply With Quote
The Following User Says Thank You to curiousB For This Useful Post:
Yoyizit (05-23-2012)
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
100amp service to 200amp service - double or single panel CapeCod153 Electrical 8 05-09-2012 09:03 PM
Wiring Size Calculations for New Service CorinthWest Electrical 7 12-07-2010 12:36 PM
Service mast options bsperr Electrical 6 12-09-2009 09:48 AM
Remodel - Moving from 200 amp service to 320 amps stevedar Electrical 20 11-29-2009 09:14 PM
Grounding for two service entrances to same house. jogr Electrical 18 09-24-2008 11:31 AM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.