[baspinall]

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

 

[kbsparky]

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.

 

[electures]

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.

 

[baspinall]

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?

 

[electures]

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.

 

[kbsparky]

#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.

 

[baspinall]

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]

Underground isn't an option. Has to be aerial.

 

[kbsparky]

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

 

[baspinall]

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.

 

[electures]

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 60°C (140°F).
(2) Conductors with higher temperature ratings, provided the ampacity of such conductors is determined based on the 60°C (140°F) 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 75°C (167°F) or higher shall be permitted to be used, provided the ampacity of such conductors does not exceed the 75°C (167°F) 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 75°C (167°F)
(2) Conductors with higher temperature ratings, provided the ampacity of such conductors does not exceed the 75°C (167°F) 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.

 

[electures]

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.

 

[kbsparky]

You missed this one:

(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.

 

[kbsparky]

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 75ºC (167ºF)

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.

 

[electures]

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.

 

[electures]

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 75ºC (167ºF)

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.

Oh darn ya got me again. Also, #2 is smaller then #1 so the 75 degree can't be applied. It is based on the wire size not what the terminal can handle. But this point is mute as long as all terminals and equipment are 75 degree rated. The only other area of concern will be where the wiring methods transition from triplex to ?. The tempature rating of the termination devices will affect the overall installation.

 

[kbsparky]

Yeah, I personally don't like doing overhead feeders using things like triplex. Too many bugs, service heads, etc. When faced with having to install a 4-wire feeder, quadplex would have to be utilized.

I wonder if there is any way the OP could use conduit, without burying it? I've seen instances where a feeder was installed using conduit that was attached or run adjacent to a fence, wall, or similar on top of the ground....

 

[baspinall]

Getting ready to leave for work but I will get pics tonight. Conduit won't work either. There is nothing but a paver patio & driveway asphalt in between my home and the garage. I can deal with running Quad or what ever I have to and transitioning to another feed to the main & sub panel if I have to do that. Be back tonight.

 

[electures]

Yeah, I personally don't like doing overhead feeders using things like triplex. Too many bugs, service heads, etc. When faced with having to install a 4-wire feeder, quadplex would have to be utilized.

I wonder if there is any way the OP could use conduit, without burying it? I've seen instances where a feeder was installed using conduit that was attached or run adjacent to a fence, wall, or similar on top of the ground....

#2 triplex is actually rated for 135 amps based on 75 degrees in 310.17. Of course he will have to switch to #3 CU or #1 AL (75 degree)to enter each building. Thought I'd correct that.

 

[kbsparky]

The problem with triplex is there are not enough conductors. Two insulated and one bare = where's the neutral?

Quadplex would be required at a minimum for a 4-conductor overhead feeder ...