Does each leg of a 220 line have to have the exact same voltage?

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LouBrandt

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Hello,

I have been having some discussions with someone regarding 220 voltage. My question is, do both legs of a 220 circuit have to have the exact same voltage for it to operate? I've always heard that 110 is not always exactly 110, so if that's the case, will a 220 line run ok, if one leg is say 112 and the other 117 or so?

Thanks,
Louis
 

Reach4

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There can be a difference. That would usually be caused by one leg having a lot more load.
 

Reach4

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Yes, but....

I presume these numbers are an example to illustrate the point. In most parts of the US, the nominal voltage is 240/120. That is plus or minus 10%. Being down to 110 would be a bit unusual, but even 108 would still be within spec.
 

Jadnashua

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In a typical US residence, you have 240vac coming in from the transformer. To get 120vac, they put a 'neutral' half-way across the transformer secondary. That's not always placed exactly perfectly, then, the load and wiring can affect the measured voltage you see. Normally, it's close, but rarely exactly the same on both legs to neutral.
 

LBrandt

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In a typical US residence, you have 240vac coming in from the transformer. To get 120vac, they put a 'neutral' half-way across the transformer secondary. That's not always placed exactly perfectly, then, the load and wiring can affect the measured voltage you see. Normally, it's close, but rarely exactly the same on both legs to neutral.

Thanks again.
 
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Hey, wait a minute.

This is awkward, but...

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