If a 220-volt breaker has 2 hot lines coming in, does it...

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Question by AL
Submitted on 11/27/2003
Related FAQ: Electrical Wiring FAQ (Part 1 of 2)
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If a 220-volt breaker has 2 hot lines coming in, does it mean any hot line coming from the power company to the panel has 110 volts only?

Answer by Dan
Submitted on 2/10/2004
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Usually the power from the utility pole transformer has three output wires. One is usually bare metal, this is the neutral, and the other two are insulated, these are both hot but 180 degrees out of phase. When either one of these hot wires is combined with the neutral it is 110 volts. When the two hot wires are combined it is 220 volts. A 220 volt breaker is a double pole breaker that switches both hots. If your neighborhood has a standard dual voltage transformer 110/220, then yes, any single hot line is 110 volts.

Answer by wdbdan
Submitted on 4/20/2004
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I have a plasma cutter set up for single phase 220. How can I wire it up with 2 phase 220 ?

Answer by mt
Submitted on 5/7/2004
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You will either have single or 3-phase. This is dependent on the transformer feeding your site. Most residential sites are single phase. Read the previous post. The potential across the two power legs is 220/single phase.

Answer by David
Submitted on 9/22/2005
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Will a portable power generator having "1 pole 240V/60Hz power outlets" work with my regular residential 220v clothes dryer plug? I would think my dryer is fed from a "2 pole" supply.

Answer by donald
Submitted on 9/25/2005
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i have 4 wires coming from my panel box. one red, one black, one white, and one bare ground wire.it is a 220 volts.i bought a 230 volt heater and it has a hook up for only three wires.i hooked up the black and white and ground. but I'm not getting the heat I'm supposed to get. it is very low heat.and the fan is slow also.can you help me?

Answer by Bryan Williams
Submitted on 8/8/2006
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I have a 110 220 volt air compressor 1.5 hp it has a problem starting up on 120 volts, would 220 have more torque and be more effiecent on the electric bill?

Answer by Scott
Submitted on 9/1/2006
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Actually, in the US, 220 is composed not of a single phase, but of two phases of 110~ that are 180 degrees apart.

Answer by CAUVIN BAYARD
Submitted on 11/15/2006
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for a single phase 220 volt with 2 hot wire you do not need neutral

Answer by ratcat
Submitted on 1/24/2007
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While it's true that the supply to the transformer is single phase and it is a center tapped transformer that gives the two 120 legs and 220 from hot leg to hot leg. But the waveforms when seen on a scope for each leg to neutral will be 180 deg out of phase. If the two legs were both 120v and of the same phase the reading from leg to leg would be zero. The center tapped transformer basically causes the phase relationship by making neutral the center tap instead of neutral at one end. What you get at your house really is 2 phase but most prefer to call it "split phase" to avoid confusion. See here. http://www.nfphampden.com/xftheory.pdf

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