I want to add a washer & dryer to my garage, but breaker box is on the wrong side of house. No matter which way I run the wire, its 110 feet of wire required.
Will 8-3 with ground work?
Or is the run too long and I need to have 6-3 with ground?
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10/3 is FINE for the dryer. 12/2 for the washer.
Typically a 220v/30 amp Dryer circuit would utilize 10/3 with ground.
According to this voltage drop table, it looks like for 100' run you would want to up-size the wire to #8 copper, to maintain voltage drop less than 3%.
So you have arrived at the correct conclusion within your question to use 8/3 with ground.
Depending on whether you have an electrical dryer or a gas dryer, the answer will be different. I am going to assume you are in the US, and using an electrical dryer. Then the calculation goes like this:
Assuming you have an electrical dryer, typical power use might be anywhere from 1800 W to 5000 W source. But let's assume the dryer you have is right at the limit of your electrical circuit - that is a 30 A, 240 V dedicated circuit. I will compute the voltage and power drop resulting from using different gages of wire, assuming that current (which is high... more likely the current is somewhere between 8 or 22 A).
Resistance of 220 (round trip!) feet of wire source and associated voltage drop and power loss (assuming 30 A current):
AWG Ohms Drop(V) Power loss 6 0.087 2.61 2.2% 8 0.138 4.14 3.5% 10 0.220 6.60 5.5% 12 0.349 10.47 8.7%
The voltage drop you will get is current times resistance (V = I x R), for example 30 x 0.087 ~ 2.61 V. The power drop goes as the square of the voltage drop, so if you lose 1% of voltage to the dryer, you lose 2% of power.
According to the National Electrical Code, you need to use 10 AWG or better to carry 30 A safely::
But just because it's code doesn't mean your dryer will be working well. All that power going into heating the wire and not drying the clothes - that's probably not what you want.
Do be careful about making sure that your wire "can breathe". If you bury it under carpets etc, it will get MUCH hotter because the heat won't be able to get away. To be safe, I would probably go with the 8 AWG wire and make sure all the power ends up drying clothes, not heating the wires.