Wire size etc.

[gmtech]

I need help sizing my feeder wire for my garage. Garage is nearing completion, and I'm a very indecisive person. I'll be feeding garage from my house 200 amp panel. House to garage is 165ft, so total run will be about 185ft.

The shop is a 30x30x12 and will be used strictly for automotive repair. Only 240 loads will be the 2 post lift that requires a 30 amp circuit but listed as 13.8 amps and a 60 gal. Compressor that also requires a 30 amp circuit but also listed as 13.7 amps. I have a 120 volt wire welder, may upgrade to a 240 190ish amp in the future but don't weld much. Will have all LED lighting on its own 20 amp circuit. Other loads will just be the normal garage items, radio, maybe a tv, battery chargers, and a fan etc. One man shop. Gas heat, no plans for A/C but maybe a window unit one day if I see the need.

Realistically, how many amps will I need??? I've used several different voltage drop calculators and they all seem to vary quite a bit.

Do I use 2-2-2-4 MHF breakered at 70 amps? Can buy locally for $1.17/foot. Or do I use 2/0 MHF and breaker it at 90-100 amps? It's closer to $2.50 a foot. It's no so much the cost, but ease of installation. Getting it into my panel, pulled thru conduit If I decide to use conduit and not direct bury it. If I do conduit, I'll have to have the 90* at each end and 2 45*'s in the run.

I know this was a long post, but I greatly appreciate any input.

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[sberry]

The number 2 and a 60 or 70 breaker. 60 is a lot cheaper and I have wired a couple dozen of these, NEVER had one call about a trip and several of them been working shops.
Had a couple of them with 2x that compressor, not a problem.

 

[gmtech]

The number 2 and a 60 or 70 breaker. 60 is a lot cheaper and I have wired a couple dozen of these, NEVER had one call about a trip and several of them been working shops.
Had a couple of them with 2x that compressor, not a problem.

Thanks! Yes, during all my late nights searching, I've ran across you saying this on more then one occasion. Just looking for reassurance lol.

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[OccupantRJ]

I also run a well equipped shop off 60 amps with success, but I had to cut loose 5,000 watts on the heat strips in my heat pump to keep the total load down. I have already run conduit for a later upgrade to 90 amps, as I am adding a second 5 hp air compressor.

 

[flan]

I couldn’t get mhf into my 60a breaker fwiw

 

[gmtech]

I couldn’t get mhf into my 60a breaker fwiw

From my research, it looks like the Square D Homeline 60amp will accept #2. Also, it appears that once you jump to the 70 amp, it will accept up to 4/0 If I recall correctly.

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[Norcal]

From my research, it looks like the Square D Homeline 60amp will accept #2. Also, it appears that once you jump to the 70 amp, it will accept up to 4/0 If I recall correctly.

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4/0 is way larger then what a 70-125A breaker can handle.

 

[Terry D]

I would try to avoid the 45's in the conduit, try to swoop the pipe in the ditch if possible. That is a long run, unless your going to put a pull box in. I only have 60 amps in my garage, but if your going to do all of this and didn't mind paying a little more, I would go with a 100 amps. Its not that much more and its there if you need it.

 

[gmtech]

4/0 is way larger then what a 70-125A breaker can handle.

Yeah im sure you are correct. Maybe it was 2/0? maybe it wasn't even that big, But either way, I knew the 70 and up breakers would accept larger wire then the 60 and below. Thanks!

I would try to avoid the 45's in the conduit, try to swoop the pipe in the ditch if possible. That is a long run, unless your going to put a pull box in. I only have 60 amps in my garage, but if your going to do all of this and didn't mind paying a little more, I would go with a 100 amps. Its not that much more and its there if you need it.

Thanks for the reply. Ill take the swoop into consideration. Wasn't sure how much "flex" I would have in 2'' pvc conduit as Ive never worked with it much, especially in the larger sizes.

 

[OccupantRJ]

The pvc most likely will have a bit of curve in it in the storage rack. I rotate the tubing and use that to my advantage. You can bend it quite a bit by using the walls of the trench to curve it around. Even being in the sun before using it helps. Also be aware that 2” sweeps with a 36” radius are available to help with pulling the wire at the bends. You may have to order them online.
My son was digging a post hole in his back yard the other day and lightly hit an electrical conduit underground. He was sure glad it was in conduit not only for safety reasons, but also no damaged wire repair needed.

 

[sberry]

I don't recall what a 70 takes, I think I got one but a 100 takes a 1/0 I believe. For this user a number 2 is going to work just fine. A hoist is so intermittent it almost doesn't count, he is correct in using the fla to do a load calc, this will work even with a bigger comp. Most ofvthe time the biggest load is going to be the comp. You don't absolutely need to weld while the comp is running but all 3 could be done with a modern wire welder without issue.
There is no reason not to be practical here, it's enough power, it's enough work. It's the whole reason they invent this wire and stock it at the stores, ideal for this.

 

[sberry]

I just did one, had it all engineered, the guy outhinks all this, actually s lends more getting wire from a bud at a poco, some genius he listens to, comes with 1/0 with a glaze in his eye, pick guy says,,, they don't make number 2,, this is an engineer, there is a difference that they don't use it and don't make it and it's pretty obvious the guy hasn't wired on this side of a meter. I change the breaker to fit, had to change lugs for n/g, use a pipe hicky to bend it all in, what a job, other details fukked up but it would have been so simple and cheaper to use the right wire.

 

[sberry]

2 will go easy in 2 inch. It will go 1 1/2 which in some cases is easier to route pipe and put holes in 100 boxes. It will go try but I sometimes put a rag and a little sauce down the pipe and ahead of it, don't need to drown it, just a little glide if You are using all the bends. I have done more in 1 1/2 than 2 for this wire. 2 is super easy for 2.

 

[toyoguy81]

I have pretty much same size shop with all the same equipment and I used aluminum #1 in conduit to 100 amp service. I have had no issues. I would wouldn't use direct bury. I would run it in conduit.

 

[Ricketts]

Subscribed, for future reference.

 

[TractorJeff]

I need help sizing my feeder wire for my garage. Garage is nearing completion, and I'm a very indecisive person. I'll be feeding garage from my house 200 amp panel. House to garage is 165ft, so total run will be about 185ft.

The shop is a 30x30x12 and will be used strictly for automotive repair. Only 240 loads will be the 2 post lift that requires a 30 amp circuit but listed as 13.8 amps and a 60 gal. Compressor that also requires a 30 amp circuit but also listed as 13.7 amps. I have a 120 volt wire welder, may upgrade to a 240 190ish amp in the future but don't weld much. Will have all LED lighting on its own 20 amp circuit. Other loads will just be the normal garage items, radio, maybe a tv, battery chargers, and a fan etc. One man shop. Gas heat, no plans for A/C but maybe a window unit one day if I see the need.

Realistically, how many amps will I need??? I've used several different voltage drop calculators and they all seem to vary quite a bit.

Do I use 2-2-2-4 MHF breakered at 70 amps? Can buy locally for $1.17/foot. Or do I use 2/0 MHF and breaker it at 90-100 amps? It's closer to $2.50 a foot. It's no so much the cost, but ease of installation. Getting it into my panel, pulled thru conduit If I decide to use conduit and not direct bury it. If I do conduit, I'll have to have the 90* at each end and 2 45*'s in the run.

I know this was a long post, but I greatly appreciate any input.

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This is similar to my current project except most of mine is Heavy Equipment and Farm Machinery repairs!
The only difference is I WILL have the A/C with a 5K Heater plus a 50 Amp Welder Outlet.
BUT these will not run at the same time! Weld with the Door open
I'm going 70 amps as realistically I don't ever see a time when the loads would exceed 60 amps Max.

 

[Bretny]

I wouldnt bother doing conduit the whole run. I have seen them full of water and they always seam to be to small for future upgrades...so just side the service a big bigger than you think you may need, direct burry it and never worry about it again.

I wouldnt bother with conduit in reguards to the power....future needs like coax, cat5/6 fiberoptic or water are a whole other story. That cheap black poly water pipe is a good thing to throw in the trench with your power. I ended up useing mine for water.

 

[Fasthotrod]

I wouldnt bother doing conduit the whole run. I have seen them full of water

For what it's worth, anything underground is considered a 'wet' location. It doesn't matter if it's PVC conduit, rigid metal conduit, etc... The raceway is there to facilitate running the conductors and/or providing a layer of protection for them. It's not really about water intrusion in that regard.

...and they always seam to be to small for future upgrades...so just side the service a big bigger than you think you may need, direct burry it and never worry about it again.

If you install a larger conduit up front, it allows you to run a smaller conductor with ease and allows for future expansion later. So if his needs today were based on lighting loads, a welder, maybe some HVAC equipment, he can go with a 60-70A circuit and be good to go. If in the future he wanted to add a plasma cutter, lathe, mill, central vac system... whatever the needs are, all he has to do is pull the existing conductors and pull in new ones. No digging required.

For what it's worth, I can get 1" PVC in 10' sticks at Lowes for $4.10/each. 2" is $8.20/each. So for a 170ft run, that's 17 sticks. 1" would cost $69.70 and the 2" would cost $139.40 For me, the extra money is worth it if I ever had concerns about future expansion/additional loads.

I wouldnt bother with conduit in reguards to the power....future needs like coax, cat5/6 fiberoptic or water are a whole other story. That cheap black poly water pipe is a good thing to throw in the trench with your power. I ended up useing mine for water.

Agreed... throw some extra 3/4" or 1" in the trench for very little cost today and you're set for things you might not have considered you needed today. I ran 2" for my mains as well as two 3/4" for other stuff. I'm already using one of the 3/4" for CAT6 to extend the network out to the shop. I'm kicking myself for not dropping in a couple of more when I had the trench open. Oh well...

Just my two cents.

Mark