[djyaz]

I'm am getting ready to run electric wire from my house to my garage, which is approx. 140 feet and 80 feet of that is underground. I don't know what size wire or what kind to use for underground. I want to have a 200 amp service, and single phase 220volts. Any help on this would be greatly appreciated.

[tkrussell]

Based on the minimal detail given, assuming full load of 160 amps at 240 volts, (80% of 200 amps) at 220 feet, you will need 250 MCM aluminum.

This will require 3- # 250 MCM AL XHHW and 1- #2 Al XHHW for the equipment ground ,pulled through 2-1/2" Sch 40 PVC conduit.

This will give you a full 200 amp service at the garage.

If you can determine what the real amp load would be, taking the type of load, such as motors, into consideration, you may be able to reduce this wire size.

At this point, all I can suggest is this apparently oversized conductor size.

Why 200 amp at the garage?

Are any motors involved? What size Horsepower?

What is the service entrance size at the home?

What does the home need for service ampacity?

XHHW insulation is rated for wet locations, which is a buried conduit.

Conduit for this needs to be at least 18" deep, if residential and/or not under roadways.

If you have never done this type of work ,you have your hands full with layout, design, material choices, proper installation, proper tools for conduit bending and wire pulling, etc.

Also to be considered is connection at the main, installation and proper grounding at the garage panel.

Are you sure your up for a project such as this?

[donf]

TK,

I have a question for you. On the screen snap shot you show the calulations for the 240 VAC drop cable size. If you look at the percentage allowed, it states 3%.

I thought that 240 VAC had an allowable percentage of 7.2%, not 3.6%.

Was

[tkrussell]

3% is the standard recommended Vd for a feeder.

Not sure where your getting 7.2%.

Oddly enough 3% of 240 volts is 7.2 volts.

Maybe this is where the confusing is?