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220Vac question

FordDude

FordDude

Well-Known Dude
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Mom sold her house and is moving. So I had to go through the garage and take possession of Dad's tools. Mom is moving to a 55+ community. She will have a 2 car garage. I now have a 220 volt compressor.
I have a work shed in my backyard. This past summer I ran underground conduit from my house to the shed so that I could have electricity. I pulled 4 12ga wires in my 3/4 inch underground conduit. But my question is if I want both 120 and 220 how many wires will I need? 3 wires are needed for 120, I pulled an extra wire for a light switch. Thanks

fd
 
220 is simply 2 phases of 110. You should probably put an electrical sub panel in the shed or in the house that feeds the shed.

The bottom line is you just wire up one of the phases, with neutral and safety ground to get 110
 
Most residential homes are 4 wire 120/240v single phase 60Hz, not 220. Often they are color coded black, red, white and green...but could be any color. Black is single phase 120v, Red is the opposing single phase 120v and white is neutral. Green is ground. It goes like this:
Black to white = 120v
Red to white = 120v (but the opposite phase)
Black to red =240v (the two 120v phases oppose each other so you get double the voltage)
In most states white (neutral) is grounded at the box.
Green Ground is attached to a ground rod that is driven into the ground at the box.

The code books usually say that 12ga copper is good for 20 amps. In reality its good for 23 amps in a confined space (like a conduit) or 41 amps in free air, but you shouldn't be doing anything like that. "In free air" would be like inside an appliance or other large enclosure. So you should have a 20 amp breaker on each of the black and red lines (or a double 20A breaker). If the total load in the shed is more than 20 amps you will pop the breaker(s). Wires inside a conduit heat up and loose conductivity so don't try to pull more than 20A through a 12ga wire. You can run any combination of 120v (like lights) and 240v (like the compressor) loads as long as you aren't pulling more than 20A out of any single wire at one time. In a straight 240v load you don't even use the white neutral wire.
 
No one can say for sure that 12 gauge is sufficient if you don't specify how long the run is and what sort of current the compressor draws... A shed in the backyard for some guys is 10 feet from their house... others its 200 feet away. Longer distances require heavier gauge wire. My 220V compressor was about 50 ft from my main panel and runs through something like 6 or 8 gauge wire. I think 10 gauge is common for electric stoves / driers. If starting from scratch, run the fattest 4 wires you can to a subpanel in the garage, then tap your 220 and 120 from those wires.
 
stangg said:
No one can say for sure that 12 gauge is sufficient if you don't specify how long the run is and what sort of current the compressor draws... A shed in the backyard for some guys is 10 feet from their house... others its 200 feet away. Longer distances require heavier gauge wire. My 220V compressor was about 50 ft from my main panel and runs through something like 6 or 8 gauge wire. I think 10 gauge is common for electric stoves / driers. If starting from scratch, run the fattest 4 wires you can to a subpanel in the garage, then tap your 220 and 120 from those wires.
Click to expand...

Yup, absolutely! If you need some help in figuring wire size, try this:
http://www.csgnetwork.com/wiresizecalc.html
 
I'll agree with most of the above. IIRC NEC code specifies 10ga. for 30A up to 100ft., than step up a gauge in wire. 12ga. is specified for 20A. 14ga. for 15A.

From Infinity and beyond

Never Argue With A Moron– They Will Drag You Down To Their Level, Then Beat You With Experience

If the women don't find you handsome, they should at least find you handy.
 
120 volt 240 volt is for pussies

I have single fase 240 volt and tripple fase 380 volt :confused::confused::confused:;)
 
i have single phase 240V and 3 phase 415V.
But low voltage is called poofter volts where i work, as the lowest we go is 66kV right up to 330kV.
 
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