running wire 150 feet to a welder

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  #1  
Old 09-07-06, 09:36 AM
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running wire 150 feet to a welder

Hi All......... What would you do???
I am planning on running wire(s) to my shed, 150 feet from my sub panel covered by a 60 amp breaker, I have two legs of 115 to the sub-panel and need to be able to weld from the shed with a small hobby welder 230VAC with a Max amp output of 120 amps with the amperage draw of 42 amps.................
My question is, how heavy must the wires be to avoid the evil voltage drop, and do I need to run two complete legs to the shed or a single run and then split at the shed, ( I allso need to supply 115 volts to the shed)
Oppinions will be appreciated, facts will be honored..... so what do you think????? Brian...
 
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  #2  
Old 09-07-06, 09:45 AM
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Brian,

First and foremost, voltage drop cannot be "avoided". All that you can do is to limit it. Shoot for less than 3 percent, although you may be willing to accept as much as five percent.

The only way to provide for both 120 and 240 volt circuits at the shed is to put in a sub panel at the shed. If you really want 42 amps for the welder, then you should plan on at least a 60 amp sub panel. Instead of feeding from a 60 amp cubpanel, I recommend that you feed from the main panel.

To figure the cable size needed, use one of the many voltage calculators abvailable on the Internet, and input the appropriate distance of the cable. Google "voltage drop calculator" to find them.
 
  #3  
Old 09-07-06, 09:57 AM
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subpanel.....

Bob thanks for the fast responce........
my subpanel outside the house was recently put in, it has two heavy cables comming off of the main panel connected to the 60 amp breaker, right now the cables are just hooked up to the buss bars with no breakers attached, could I just tie into them and continue to a subpanel at the shed with one run of wire ( heavy) or should I run two sets of wires out to the shed?? does the question make any sence? I guess I am confussed as to how many wires need to be run to the shed......... thanks for any input Brian...
 
  #4  
Old 09-07-06, 10:55 AM
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If your sub panel at the house has no breakers installed then you have two ways to utilize it.

Use it as a juction box. Connect the new cable (for the shed) to the cable coming in. No breaker required or needed.

Use it as a sub panel. It will be a 60 amp sub panel, with a 60 amp feed to the shed.

Either way, to compute your voltage drop, use the entire length of both cables, from the main panel to the sub panel at the house, and then to the shed.

As for what you run to the shed:

Code allows one, and only one, circuit to an outbuilding such as a shed. To serve both 240 volt and 120 volt loads at the shed requires a sub-panel.
 
  #5  
Old 09-07-06, 11:15 AM
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OK that sounds good to run only one run to the shed and then split it as needed..... 150 feet using 6awg nets approx 2.5% with a voltage drop of 6 volts........ Thanks for all the info......... Brian...
 
  #6  
Old 09-07-06, 11:24 AM
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It appears that you are using the 42 amp dar in the calculation, and only the 150 feet.

If the draw is closer to the 60 amps, your voltage drop increases.

Also, does that 150 feet represent the distance from the main panel, or only from the sub panel at the side of the house?

And, your terminology is not quyite correct. You will be running one CABLE to the shed. The cable needs to contain four wires. You might be able to get away with three wires, but I do not recommend it. I recommend the full four wire feed to the shed.

The sub panel at the shed needs a main breaker, it needs have a ground rod, and the neutral and ground need to be isolated (assuming a four wire feed).
 
  #7  
Old 09-07-06, 11:30 AM
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well the distance from the panel to the subpanel outside the house is only 4 feet, my actual measurement from the panel is 146 feet to the spot where I need the welder access so 150 is spot on... the 6awg is 94 cents a foot and I am thinking of using ground/nutral of 8awg at 65 cents a foot........ or would I be penny stoopid to reduce the size of the ground/neutral line to the shed, once in place I will have to live with it, should I run three strands of 6 awg??? Brian... the 6/3 is 2.99 a foot BTW
what would you do???
 
  #8  
Old 09-07-06, 11:36 AM
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If you are talking about individual wires then don't forget to add the cost of the conduit. What is the cost of 6/3 (with ground) UF cable?

I would probably go with a smaller neutral, and certainly with a smaller ground. Without reference materials in front of me I can't say what is necessary.

At that distance from the main panel to the existing sub panel, I would bypass the sub panel and go straight from the main panel to the shed.
 
  #9  
Old 09-07-06, 11:39 AM
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OOPS. I answered to quickly..... one cable with four wires does make more sence..... that way I can isolate the ground wire. another dumb question. when you say the shed needs a main panel , that would be first from the house then to a subpanel outside the shed to the welder plug.... is that right or did I missunderstand you???
 
  #10  
Old 09-07-06, 11:42 AM
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The shed needs a panel. Since it is not your main panel, it is a sub panel.

I would put the panel INSIDE the shed. Then from the panel inside the shed run a circuit fed by a circuit breaker for the welder, and for any lights or recepacles you want.
 
  #11  
Old 09-07-06, 11:47 AM
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the home depot sells 6/3 UF ( direct Burial) for 3.66 a foot, you are right, I forgot to figgure in the cost of conduit for the 6/3 with bare copper ground wire at 2.99 a foot. Hm now you are making me go get the calculater hahahaha Brian...
 
  #12  
Old 09-07-06, 11:51 AM
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you are answering so fast it is like a chat room here haha.... OK now I understand the panel question....... Thank you for all your information...... the fog is lifting and clarity is in view.................. thanks Brian...
 
  #13  
Old 09-07-06, 11:51 AM
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For a 150' run, I calculate just under 3% voltage drop when pulling 50A on a 240V circuit when running #4 CU. If you use #6, you'd be a little over 3% drop, but under 5%. If you add in the drop going from the main panel to the subpanel, you'd probably want to stick with #4 CU, if it's a concern. But, copper is really expensive, and with 150' of cable to buy, you may not mind the voltage drop that much and stick with #6. You'll find that most things like lights and motors are OK with a little voltage drop, while electronics aren't.

If the subpanel in the house is unused, I'd just use it as a junction box, instead of getting a new DP breaker and pulling a new run from the main breaker to the garage. The only reason I'd see to make a new run from main panel to garage is if you wanted more than 60A. You're limited by the size of the wiring from the main to the currently existing subpanel, which is probably #6 CU.

Still, for a hobby welder, 60A is going to be a lot of juice. Since you're not likely to be running any other heavy-current appliances at the same time as the welder (probably just lighting, maybe a fan, but no table saws), I'd bet you're fine with 60A available in the garage. Unless you foresee welding becoming an obsession, and moving up to a bigger welder...

Do yourself a favor though, and run it in oversized conduit, so you can change your mind and run a larger feeder in the future if you want to. While you've got the ground torn up, you may also want to run another conduit for cable, phone, internet, etc, unless you're pretty sure you won't ever want that stuff.
 
  #14  
Old 09-07-06, 12:12 PM
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it is a nice shop but a rough one, no computers or other electrical entrapments, just saws and drills of all kinds ect hahahaha so I can probably live with the small voltage drop... I just got done doing a cost analysis and using UF compared to NM would be 101 dollars more... 1 1/2 inch conduitt (pvc) with joints and glue pak will run 88.98 . 2inch pvc conduitt will run 113.93 so really and I do not expect to upgrade ever, (oh no, murphys law inserted here) I think I can live with the UF ( burry it and forgett it untill a shovel hits it) style cable.. that does last forever doesn't it?? .... thanks for all the info Brian...
 
  #15  
Old 09-07-06, 12:23 PM
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"I just got done doing a cost analysis and using UF compared to NM would be 101 dollars more"

You can't use NM cable for this kind of application, it's not rated for wet locations. It's going to be either UF buried, or THWN in conduit. You should probably go and re-run your numbers.


"I think I can live with the UF ( burry it and forgett it untill a shovel hits it) style cable.. that does last forever doesn't it"

Heh... nothing lasts forever, but I wouldn't really worry about burying UF so long as you go deep enough. Personally I'm averse to direct burial cable (maybe because I seem to do a TON of digging in my own yard), and I like to put stuff in conduit.
 
  #16  
Old 09-07-06, 12:37 PM
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arnie...
Yep you are right nm cannot be burried. the thn runs single strand 94 cents a foot....... I was dealing with the same associate all along and she forgott that point . Hmmmm anyway, I think in the long run time and such, I will go with the burial cable, a lot less fuss and muss for now, I will probably regrett that years from now when the ole lady wants a tree planted hahahahahah OH for refrence, how deep would you go with that type of cable??? Brian...
 
  #17  
Old 09-07-06, 12:55 PM
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Go 24" deep for direct burial in the ground with no protection whatsoever. If you're worried about damage, you can go 18" deep and pour 2" of concrete over top of the cable. Don't actually encase the cable, put some sand or gravel on top first, then concrete. It's only 6" deep if you use RMC or IMC metallic conduit - a bonus if you hate digging. While not required by code, you can put a warning ribbon in the trench. Get a roll of that yellow 2" plastic CAUTION tape, and bury it in the trench a foot above the cable.

Take lots of pictures of the trench location, it might help in case you need to dig in that area again. And if you ever do dig in that area again, be sure and deenergize that cable, just in case, until you're done digging and you're sure you didn't nick it.
 
  #18  
Old 09-07-06, 02:39 PM
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One point and it may seem rather simple and unnecessary but I really get tired of seeing people dig trenches before they mark or have marked there existing buried cables both utility and comm. It really sucks when you cut a cable.

Roger
 
  #19  
Old 09-08-06, 04:16 AM
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Thanks All

Thank you all for your information, these forums are an excellent source of information and knowledge for those of us who just don't get it at first..... Cudos to you all, Thanks Brian...
 
  #20  
Old 09-10-06, 09:45 PM
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Originally Posted by arniebuteft
For a 150' run, I calculate just under 3% voltage drop when pulling 50A on a 240V circuit when running #4 CU. If you use #6, you'd be a little over 3% drop, but under 5%. If you add in the drop going from the main panel to the subpanel, you'd probably want to stick with #4 CU, if it's a concern. But, copper is really expensive, and with 150' of cable to buy, you may not mind the voltage drop that much and stick with #6. You'll find that most things like lights and motors are OK with a little voltage drop, while electronics aren't.

If the subpanel in the house is unused, I'd just use it as a junction box, instead of getting a new DP breaker and pulling a new run from the main breaker to the garage. The only reason I'd see to make a new run from main panel to garage is if you wanted more than 60A. You're limited by the size of the wiring from the main to the currently existing subpanel, which is probably #6 CU.

Still, for a hobby welder, 60A is going to be a lot of juice. Since you're not likely to be running any other heavy-current appliances at the same time as the welder (probably just lighting, maybe a fan, but no table saws), I'd bet you're fine with 60A available in the garage. Unless you foresee welding becoming an obsession, and moving up to a bigger welder...

Do yourself a favor though, and run it in oversized conduit, so you can change your mind and run a larger feeder in the future if you want to. While you've got the ground torn up, you may also want to run another conduit for cable, phone, internet, etc, unless you're pretty sure you won't ever want that stuff.
Unless you will be using your welder wide open I doubt if the larger wire would help that much. I rarely use my stick welder at over 120 amps,( about 30 amps at the wall) the last time I cranked it up was to cut up some scrap so it would fit in the back of the truck. I didnt check out any charts so I accept that the #4 and #6 numbers are good and would go with the #6. The one thing that might give you a problem latter on is if you decide to put in a big air compressor and it kicks on while you are welding(bite mark #123).

Jimmie
 
  #21  
Old 09-11-06, 04:17 AM
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Smile

Another thought...You can buy a factory assembled aluminum feeder cable that's rated for 100 amps for about $1.85 per foot.
It's primarily used for mobile home feeders, but it will work fine and is code compliant for your installation.
It has 2 conductors of #2 aluminum, 1 conductor of #4 aluminum and 1 conductor of #6 aluminum. It is rated for direct burial (24") or you can put it in conduit. It's 4 seperate conductors that are spirally wound around each other without a overall covering. It's rated USE with a cross rating of RHH which means that it can be direct buried and also be used inside a building.
It's what I would use.
It's available at Lowes or Home Depot.
steve
 
  #22  
Old 09-12-06, 07:06 AM
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Yup, I almost never use copper for those feeders, its number 2 alum, Lowes has it in quad and I am sure it went up but I paid 1.10 last fall. I like this for long runs, I usually use a 60 to feed it but at that pull V drop isnt much of an issue.
 
  #23  
Old 09-14-06, 04:57 PM
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Wow..... that is a huge savings,,,,, I have yet not done anything in regards to getting it streched out yet so I will look into that....... thanks a Bunch Brian...........
 
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