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 06-26-2011, 06:26 PM   #1
Newbie
 
Join Date: Feb 2010
Posts: 18
Share |
Default

Running electric to detached garage?


OK here is what I am doing. I need to have two 220 circuits out in my detached garage. This will be used by my welder and a ceiling heater. I have the specs for each. My run will be approx. 65 feet. Other than the welder and heater I have some fluorescent lighting, 110 single stage air compressor. Nothing really running at the same time except in the winter when the heater may be on.
In the house I have my 200 amp service panel in the basement. In the garage I currently have a sub panel being feed by a very old 110 which is an aerial wire.
Here is my question. What gauge wire should I run? Can I get away with aluminum? What breakers should I use at each panel? I have a 60, 40 & 30 breakers at hand that I can use.

Specs:

Welder is a Miller 210 - 110/220volt mig.
Amp range 30-210
Amps Input rated load Output 230V, 60 HZ, Single phase, 24.3
Max open circuit voltage DC 34

Heater:
Voltage 208/240
Watts 4500/6000
Amps 21.6/25.0
Motor Watts 16


Thanks for any help here. Priority is to get my welder up so I can do some frame work on a hot rod I'm tooling on.

Brian

baspinall is offline   Reply With Quote
Old 06-26-2011, 06:54 PM   #2
Electrical Contractor
 
kbsparky's Avatar
 
Join Date: Sep 2008
Location: Delmarva
Posts: 3,368
Default

Running electric to detached garage?


1) You will need to install a new sub-panel at the garage, fed with a single feeder from the main panel. I would recommend a 100 Amp service for your loads. At minimum, a 60 Amp feeder might work, but with both the heater and welder on at the same time, you will be maxed out. You need to consider other loads, such as lighting and general receptacle outlets.

You could install a #2 Aluminum feeder, protected by a 90 Amp breaker if desired.

2) The heater will need at least a 30 Amp circuit. If your supply is 240 Volts, then the heater rating that you will need to use is 6000 watts. In that case, you need to go to a 35 Amp circuit for the heater, since its rating exceeds 80% of a 30 Amp circuit. (fixed electric space heaters are considered to be continuous loads) You'll have to install that on a #8 copper line, too.

3) The welder would need a circuit capable of handling 25 Amps, based on its rating. You could use up to a 50 amp breaker on this circuit, with a #10 copper wire feeding its circuit.

__________________
-KB

Life is uncertain -- eat dessert first!!
kbsparky is offline   Reply With Quote
Old 06-26-2011, 07:04 PM   #3
Lic Electrical Inspector
 
electures's Avatar
 
Join Date: Dec 2009
Location: The Great Police State of New Jersey
Posts: 1,663
Default

Running electric to detached garage?


Quote:
Originally Posted by kbsparky View Post
1) You will need to install a new sub-panel at the garage, fed with a single feeder from the main panel. I would recommend a 100 Amp service for your loads. At minimum, a 60 Amp feeder might work, but with both the heater and welder on at the same time, you will be maxed out. You need to consider other loads, such as lighting and general receptacle outlets.

You could install a #2 Aluminum feeder, protected by a 90 Amp breaker if desired.

2) The heater will need at least a 30 Amp circuit. If your supply is 240 Volts, then the heater rating that you will need to use is 6000 watts. In that case, you need to go to a 35 Amp circuit for the heater, since its rating exceeds 80% of a 30 Amp circuit. (fixed electric space heaters are considered to be continuous loads) You'll have to install that on a #8 copper line, too.

3) The welder would need a circuit capable of handling 25 Amps, based on its rating. You could use up to a 50 amp breaker on this circuit, with a #10 copper wire feeding its circuit.
#2 AL is rated for 75 amps with an 80 amp breaker.
__________________
All responses based on the 2011 NEC.
If you live in New Jersey click here. All other states click here.
Please check with local, county and state officials as laws may vary.
Sizing motors here. Online motor calculator here. Online calculators here.
electures is offline   Reply With Quote
Old 06-26-2011, 07:18 PM   #4
Newbie
 
Join Date: Feb 2010
Posts: 18
Default

Running electric to detached garage?


Thank you for the information. 100 Amp was what I was hoping to run. I was thinking Aluminum would be a way to save some money.
Assume I run a #2 Aluminum feeder with a 90 amp breaker.This run will be exiting the basement of my house and running up the outside wall to a ceramic screw type insulator then aerial over to the garage onto another insulator. . Would it be best to run a outdoor conduit for this or is this cable insulated so I can strap it like my main feed?
baspinall is offline   Reply With Quote
Old 06-26-2011, 07:30 PM   #5
Lic Electrical Inspector
 
electures's Avatar
 
Join Date: Dec 2009
Location: The Great Police State of New Jersey
Posts: 1,663
Default

Running electric to detached garage?


Quote:
Originally Posted by baspinall View Post
Thank you for the information. 100 Amp was what I was hoping to run. I was thinking Aluminum would be a way to save some money.
Assume I run a #2 Aluminum feeder with a 90 amp breaker.This run will be exiting the basement of my house and running up the outside wall to a ceramic screw type insulator then aerial over to the garage onto another insulator. . Would it be best to run a outdoor conduit for this or is this cable insulated so I can strap it like my main feed?
#2 AL is rated for 75 amps not 90 amps. 80 amp breaker.
__________________
All responses based on the 2011 NEC.
If you live in New Jersey click here. All other states click here.
Please check with local, county and state officials as laws may vary.
Sizing motors here. Online motor calculator here. Online calculators here.
electures is offline   Reply With Quote
Old 06-26-2011, 07:48 PM   #6
Electrical Contractor
 
kbsparky's Avatar
 
Join Date: Sep 2008
Location: Delmarva
Posts: 3,368
Default

Running electric to detached garage?


Quote:
Originally Posted by electures View Post
#2 AL is rated for 75 amps not 90 amps. 80 amp breaker.
Where are you looking in the Code for this information?

#2 Al type XHHW, or THHN is rated for 90 Amps. This would be the type of conductor that would be installed in an underground conduit, such as PVC for a detached structure.
__________________
-KB

Life is uncertain -- eat dessert first!!
kbsparky is offline   Reply With Quote
Old 06-26-2011, 07:56 PM   #7
Newbie
 
Join Date: Feb 2010
Posts: 18
Default

Running electric to detached garage?


Sorry, didn't catch the first post. So what gauge would you run for a 100 Amp service or should I go with a 75 amp breaker.
baspinall is offline   Reply With Quote
Old 06-26-2011, 08:03 PM   #8
Newbie
 
Join Date: Feb 2010
Posts: 18
Default

Running electric to detached garage?


Underground isn't an option. Has to be aerial.
baspinall is offline   Reply With Quote
Old 06-26-2011, 08:13 PM   #9
Electrical Contractor
 
kbsparky's Avatar
 
Join Date: Sep 2008
Location: Delmarva
Posts: 3,368
Default

Running electric to detached garage?


Aerial, eh? That's a whole different ballgame. You might want to provide some more details about your site plan.
__________________
-KB

Life is uncertain -- eat dessert first!!
kbsparky is offline   Reply With Quote
Old 06-26-2011, 08:17 PM   #10
Newbie
 
Join Date: Feb 2010
Posts: 18
Default

Running electric to detached garage?


I'll post some pictures tomorrow. It will explain it a little better than I can. There's already an old line run. I want to replace it and update my detached garage panel.
baspinall is offline   Reply With Quote
Old 06-26-2011, 09:15 PM   #11
Lic Electrical Inspector
 
electures's Avatar
 
Join Date: Dec 2009
Location: The Great Police State of New Jersey
Posts: 1,663
Default

Running electric to detached garage?


Quote:
Originally Posted by kbsparky View Post
Where are you looking in the Code for this information?

#2 Al type XHHW, or THHN is rated for 90 Amps. This would be the type of conductor that would be installed in an underground conduit, such as PVC for a detached structure.
110.14(C)(1)(a)(1) & (2)

(C) Temperature Limitations.
The temperature rating associated with the ampacity of a conductor shall be selected and coordinated so as not to exceed the lowest temperature rating of any connected termination, conductor, or device. Conductors with temperature ratings higher than specified or terminations shall be permitted to be used for ampacity adjustment, correction, or both.
(1) Equipment Provisions.
The determination of termination provisions of equipment shall be based on 110.14(C)(1)(a) or (C)(1)(b). Unless the equipment is listed and marked otherwise, conductor ampacities used in determining equipment termination provisions shall be based on Table 310.16 as appropriately modified by 310.15(B)(6).
(a) Termination provisions of equipment for circuits rated 100 amperes or less, or marked for 14 AWG through 1 AWG conductors, shall be used only for one of the following:
(1) Conductors rated 60C (140F).
(2) Conductors with higher temperature ratings, provided the ampacity of such conductors is determined based on the 60C (140F) ampacity of the conductor size used.
(3) Conductors with higher temperature ratings if the equipment is listed and identified for use with such conductors.
(4) For motors marked with design letters B, C, or D, conductors having an insulation rating of 75C (167F) or higher shall be permitted to be used, provided the ampacity of such conductors does not exceed the 75C (167F) ampacity.
(b) Termination provisions of equipment for circuits rated over 100 amperes, or marked for conductors larger than 1 AWG, shall be used only for one of the following:
(1) Conductors rated 75C (167F)
(2) Conductors with higher temperature ratings, provided the ampacity of such conductors does not exceed the 75C (167F) ampacity of the conductor size used, or up to their ampacity if the equipment is listed and identified for use with such conductors

Conductors #14 through #1 shall be based on the 60 degree column of Table 310.16.

#2 AL is rated at 75 amps from the 60 degree column.

90 degree column is used for derating purposes only.

__________________
All responses based on the 2011 NEC.
If you live in New Jersey click here. All other states click here.
Please check with local, county and state officials as laws may vary.
Sizing motors here. Online motor calculator here. Online calculators here.

Last edited by electures; 06-26-2011 at 09:30 PM.
electures is offline   Reply With Quote
Old 06-26-2011, 09:24 PM   #12
Lic Electrical Inspector
 
electures's Avatar
 
Join Date: Dec 2009
Location: The Great Police State of New Jersey
Posts: 1,663
Default

Running electric to detached garage?


Quote:
Originally Posted by baspinall View Post
Underground isn't an option. Has to be aerial.
If you use #2 AL triplex it is rated for 110 amps based on Table 310.17. However, whatever wire is used to leave and enter each building has to sized from Table 310.16.
__________________
All responses based on the 2011 NEC.
If you live in New Jersey click here. All other states click here.
Please check with local, county and state officials as laws may vary.
Sizing motors here. Online motor calculator here. Online calculators here.
electures is offline   Reply With Quote
Old 06-26-2011, 11:45 PM   #13
Electrical Contractor
 
kbsparky's Avatar
 
Join Date: Sep 2008
Location: Delmarva
Posts: 3,368
Default

Running electric to detached garage?


You missed this one:

Quote:
(3) Conductors with higher temperature ratings if the equipment is listed and identified for use with such conductors.
I used the 75 degree column in determining that #2 XHHW AL is suitable for a 90 Amp feeder, when connected to breakers with terminals rated for 75 degree terminations.

This is the problem I have with some inspectors. They have a selective memory when it comes to Code issues. While I accept that provisions (1) and (2) are valid when equipment is not marked, this is not the case when using UL listed circuit breakers which clearly have 75 degree temperature ratings for its wire terminals.
__________________
-KB

Life is uncertain -- eat dessert first!!

Last edited by kbsparky; 06-26-2011 at 11:50 PM.
kbsparky is offline   Reply With Quote
The Following 2 Users Say Thank You to kbsparky For This Useful Post:
mpoulton (06-27-2011), SD515 (06-27-2011)
Old 06-27-2011, 12:13 AM   #14
Electrical Contractor
 
kbsparky's Avatar
 
Join Date: Sep 2008
Location: Delmarva
Posts: 3,368
Default

Running electric to detached garage?


Let's take this one step further, showing the next section of the Code that you conveniently ignored:

(b) Termination provisions of circuits or equipment for circuits rated over 100 amperes, or marked for conductors larger than 1 AWG, shall be used only for one of the following:

(1) Conductors rated 75C (167F)


I stipulate that most equipment used in this case as in 90 and 100 Amp breakers have lugs marked for conductors greater than #1, and therefore the provisions of (a) do not apply. I know for a fact that Square D breakers of these ratings are marked for a 2/0 conductor.

I also checked Cutler-Hammer's web site, and theirs are marked for a 1/0 conductor, also larger than a #1.
__________________
-KB

Life is uncertain -- eat dessert first!!

Last edited by kbsparky; 06-27-2011 at 12:18 AM. Reason: Added CH info
kbsparky is offline   Reply With Quote
The Following 3 Users Say Thank You to kbsparky For This Useful Post:
electures (06-27-2011), mpoulton (06-27-2011), SD515 (06-27-2011)
Old 06-27-2011, 04:26 AM   #15
Lic Electrical Inspector
 
electures's Avatar
 
Join Date: Dec 2009
Location: The Great Police State of New Jersey
Posts: 1,663
Default

Running electric to detached garage?


Quote:
Originally Posted by kbsparky View Post
You missed this one:



I used the 75 degree column in determining that #2 XHHW AL is suitable for a 90 Amp feeder, when connected to breakers with terminals rated for 75 degree terminations.

This is the problem I have with some inspectors. They have a selective memory when it comes to Code issues. While I accept that provisions (1) and (2) are valid when equipment is not marked, this is not the case when using UL listed circuit breakers which clearly have 75 degree temperature ratings for its wire terminals.
Actually I was testing you to see if you knew. Very good. The only other area of concern is the tempature rating of any termination devices.

__________________
All responses based on the 2011 NEC.
If you live in New Jersey click here. All other states click here.
Please check with local, county and state officials as laws may vary.
Sizing motors here. Online motor calculator here. Online calculators here.
electures is offline   Reply With Quote
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
need opinons on electric to a garage jerryinmich57 Electrical 2 01-29-2011 09:28 AM
Standby generator connected via detached garage? vsheetz Electrical 22 04-04-2009 02:44 AM
Subpanel - detached garage without a floor SAS Electrical 12 03-05-2009 11:42 AM
Detached garage setup - Switch loop setup jamiedolan Electrical 3 02-07-2009 12:08 PM




Top of Page | View New Posts

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