Wire size calc?

[DangerousDan55]

Hello yall. Looking to install a sub-pannel in my new 40x60 shop.
My question is on the "wire sizing calculators" found on line.
http://www.paigewire.com/pumpWireCalc.aspx

It asks for either 120 or 240 voltage in the calcs.
Am I correct in using the 240V calc option, being that I wish to run two 120V conductors & neutral, to supply 240V.
The 120-240 make a differance in wire size between the two choices.
120V requires either 1/0AWG Co or 3/0AWG Al
240V requires either 1AWG Co or 1/0AWG Al
By the way, i have on the house 200A service. Plan to install a 100 or 125A breaker in the main house panel, run 270' to the shops new sub-panel.

Thanks for any advise.

 

[DekeT]

Am I correct in using the 240V calc option, being that I wish to run two 120V conductors & neutral, to supply 240V.

Thanks for any advise.

Not sure what you mean by running two 120v conductors for your 240 service. Are you hooking up to 120v breakers?

 

[dimarcelli]

It'll be 240. Two hots, neutral and ground. For 270 feet i would go with 3/0 aluminum SER. You'll avoid a significant voltage drop with the bigger wire.

Remember when installing the sub, ground and neutral bus bars are not bonded in the panel.

 

[930dreamer]

http://www.calculator.net/voltage-d...e=270&distanceunit=feet&amperes=100&x=63&y=13

 

[pattenp]

For aluminum power feed at 270' to provide 100A you'll need 3/0 or 4/0 for 125A. You can not use SER cable assuming the install is under ground. You need to use URD or Mobile Home Feeder(MHF) for under ground. Of the two I prefer the MHF because it can be run inside of the structure in conduit. URD can not enter the structure because it's insulation is not fire resistant rated. Another thing is the MHF does not come in 3/0, so you'd need to use 4/0. So you might as well go 125A if using the 4/0 MHF.

Edit: you can also use individual wire that is THWN rated. You do need 4 conductors for the feed. You may find that you can get by with a 100A breaker feeding 2/0 Al. The voltage drop doesn't get above 3% until you get to around a load of 90A.

Just what do you plan on powering that you need 100A -125A in your shop?

 

[DangerousDan55]

Thanks for input.
I would be going under ground.
Note; the GE Breaker specs say:
125A wire size 2 to 2/0 AWG Al
100A wire size 4 to 1/0 AWG Al
There is my issue here now....

Now thinking about, but, not verified yet...
I already have a 2 pole feed-thru lug GE "THLK2200" & 3 feet of 4/0 Al
Install a "Safety Switch disconnect" fused @ 100A next to the house panel.

Feed 240V 200A from the house panel, thru the "feed-thru lug", to the Safety disconnect & thru the 100A fuse, then, run 3/0 Al underground 270' to the shop & into a 100A main breaker panel.

(not sure if 4/0 will fit the 100A safety switch) GE site doesnt conferm wire size.

I know, your thinking, why not just go with 4/0 all the way. Not much room in the house panel for the large wire bends. Unless, I'm alowed to drill a new hole so that the wire in the panel has a straight run out of the panel, into PVC, underground & to the shop.
Could I do that??

 

[DangerousDan55]

Sorry PATTONP, i didnt read you bottom note.
My useage:
Car lift @220V 20A
Air comp @ 220V 7.5A
Wire feed @ 110V 20A
Florecent lights@ aprox 3amps
Stick welder 220V 40A (future item)
NO air cond. just fans
Hand tools....
Not for profit work, just myself.

 

[pattenp]

My opinion is to go with the 125A breaker with 2/0 AWG Al. I don't think the VD will be a problem for you being a one man shop. I still recommend using Mobile Home Feeder, get 2/0-2/0-2/0-1. See below link...

http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet15

Edit: It's okay to drill a larger hole in the panel for the wire.



*

 

[DangerousDan55]

That is So Cool!
Thanks for you help.
You are correct, I dont use most of the high amp stuff often.
Welder, once every 3 months.
Car lift, twice a month.
Mostly I use lights, radio, fan, grinder/buffer & of course air comp.

If I can only figure out how to post pictures that I can share....
Thanks again.

 

[DangerousDan55]

Now I just need to find a local supply here in Houston area.

 

[pattenp]

Do you have a Lowes or Home Depot nearby? Check them for the MHF cable.

Edit: Don't let them sell you cable that is only rated USE-2. It can only be used outside of the structure. The MHF cable is USE-2/RHH/RHW rated which means it can be used inside, but does need to be in conduit.

 

[DangerousDan55]

Yep about 15 miles. I live in Hockley, outside of Houston.
Ill look them up on the net.

 

[TheEquineFencer]

Have you thought about putting in a seperate service?