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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    How many amps will your dryer require? – BMitch May 1 '16 at 13:25
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    Is it a Dr. Seuss holiday or something? Everyone is speaking in rhyme... – Darrel Hoffman May 1 '16 at 17:58

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.

  • "220V" is a generic term, although it is incorrect. 240V would be correct, but a typical electric dryer in North America would be 120/240V. ....Also, 5% would be perfectly acceptable for this type of circuit. – Speedy Petey May 1 '16 at 20:00
  • I based the text of the answer (220v) on the table heading to avoid confusion. @SpeedyPetey – Tyson May 1 '16 at 20:02
  • The NEC recommends the voltage drop be limited to 3% for branch circuits or feeders and 5% for both. This this is always contained in an informational note so it is not an enforceable part of the code but it is advisable. So, 5% for a branch circuit is too high according to the Code but 5% for the entire circuit from the service to receptacle is acceptable. – ArchonOSX May 7 '16 at 11:29
  • I'd have to agree with Tyson. A 100 foot run in commercial / industrial work is usually required by the job specifications to be upsized one wire size. This is a good general rule of thumb to follow. – ArchonOSX May 7 '16 at 11:35

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::

enter image description here

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.

  • Typical power for an electric dryer IS NOT 1800 watts. Even your link says 1800-5000 W with typical being 3000 watts. ...... I have yet to see a typical full-sized electric dryer that required less than a 30A circuit. – Speedy Petey May 1 '16 at 19:59
  • @SpeedyPetey - you're right, I updated for the whole range of power from 1800 to 5000. But since the original question didn't specify the wattage, it's hard to give a definitive answer. Better to show the method. – Floris May 1 '16 at 20:03
  • Oh no, thats wrong. Most dryers demand a dedicated 30A circuit. If they don't actually draw 30A, they require a de-rate that requires you to compute load as if they do. That's because they are engineered to the alllowed limits of a 30A circuit - makers would prefer to go higher still, because even at 30A they are slow to dry compared to gas. Your thoroughness is admirable, but please! Recompute for an honest 7200W (240V x 30A). – Harper - Reinstate Monica May 2 '16 at 2:34
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    @Floris 22A or 23A is typical for dryers and hot water heaters. Code requires a derate so you multiply by 125%, so, 27.5A to 28.75A. See how that nicely dovetails to a 30A dedicated circuit. By design. You don't to get to throw in a bunch of fudge factors, because a committee of pretty smart people who look at fire reports all day, have already done so and written NEC. – Harper - Reinstate Monica May 2 '16 at 3:47
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    Yes, coming from an EE perspective, code electrical is a perplexing beast, full of strange idioms, awful compromises and clever hacks. Eventually you go "OH. That's why they do that." The committee does have EEs but also boots-on-ground code electricians, fire inspectors, insurers, manufacturers and homebuilders. Oh, and lawyers, as civil liability is a factor too. An astonishing amount of, well not engineering exactly, but "grand design" has gone into keeping things K.I.S.S., partly to minimize arguments between electricians and code inspectors. – Harper - Reinstate Monica May 2 '16 at 4:09

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