1

I need to run a 220 line about 100ft from my breaker box to where the sauna be located.

The manual says for an 8 kw heater, 8-2 w/ground copper; 40 amp non GFCI breaker But it also says for distances “up” to 30 ft.....

So what if it’s 100?

enter image description here

2
  • 1
    Longer distances require larger wire to reduce voltage drop due to resistance. Have you looked at standard wiring charts for the correct size?
    – isherwood
    Jan 31, 2018 at 18:43
  • What size are the pumps?
    – Ed Beal
    Jan 31, 2018 at 21:25

1 Answer 1

1

Having run a few of these calculations, the break point is usually a little past 100' if you want to hold voltage drop below 3%. However, for a resisitive heater, there is no reason to hold voltage drop below 3%. It is a waste of money.

Regardless, 8000 watts happens at 33.33 amps on US 240V* voltage. The UL-approved product instructions call for 8 AWG wire. Southwire's voltage drop calculator tells me those conditions at 100' run yield 1.92% voltage drop on 8 AWG.

If the hot tub failed on 2% power drop, there is no way UL, CSA or TUV would list it.

You're all set.


* power was 110/220 when AC power was first mass marketed in 1915-ish, and the term stuck. Today, US voltage is 120/240. Except in Puerto Rico, where it's 0!

2
  • Agree but use a GFCI breaker .
    – Ed Beal
    Jan 31, 2018 at 21:49
  • @EdBeal definitely. But the instructions prohibit that, so use a GFCI deadface lol! Unrelated, I've always wondered why hot tubs use resistive heaters and not heat-pump. They'd be so much more efficient, and better yet, electricity would be nowhere near the water (it'd be a freon-water interchange). Though they'd become a motor load. Jan 31, 2018 at 22:38

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.