Currently I have a 50 amp breaker (220v) running to my pool panel. My pool panel has two 110v outlets and a 20 amp (220v) to run my pool pump. I want to add an electric pool heater which will be a 40-60 amp (220v) dedicated circuit that will be added to my pool panel. With that being said, I guess I need to increase the breaker size in my house that goes to my pool panel from 50 amp to 70 amp. So my question is wiring size. I need to make sure the wiring that's existing is the correct gauge for me to increase the breaker size. I dont know exactly what gauge it is but this is what it says on the wire: CSA T90 NYLON OR TWN75 F11 NOM - ANCE 90°C RoHS 600VOLTS VW

I dont know if this is needed but my main breaker in my house is 200 amp. The wiring going to my pool panel is in gray conduit from my breaker panel in my house to my pool panel which is located outside obviously (which I believe is done that way to be up to code). Electrician ran that for me about 7 years ago.

  • 1
    What are the nameplate ratings on your pool pump and pool heater? Commented Aug 1, 2017 at 11:48
  • Yes, notor nameplate ratings. Also there must be more text on the wire, we're looking for a numeral and then "AWG". Check other wires as they are likely all the same size. Commented Aug 1, 2017 at 14:14
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    If the wire is #6 you can do that. I suspect the electrician ran #8 since that would be all you need for a 50 amp circuit. If that's the case, you can't do that. 😞
    – ArchonOSX
    Commented Aug 1, 2017 at 15:56
  • Pump: 1.50HP, 230V; 3450RPM S.F.1.10l; Max AMPS: 16.0; Heater: kW Input: 6.8; Voltage/Hz/Phase: 208-230/60/1; Min Circuit Ampacity: 43.3; Max Fuse Size: 60 Wire Size: 8 AWG (8.37mm). I guess there is my answer. 8g is just too thin...
    – reekasr
    Commented Aug 1, 2017 at 21:24
  • @reekasr -- yeah -- thank gosh the wire's in conduit, so it's easy to replace! Commented Aug 1, 2017 at 22:24

1 Answer 1


All I am trying to do is answer your basic question. Simplistically put, the NEC requires electrical conductors to be protected by overcurrent protection that matches the current carrying capacity of said conductor. So in your case you must run a #4 for your 70A breaker.

If you are trying to determine a wire size you should be looking for a marking similar to this.

enter image description here

The reason everyone is asking questions is because we think we could help if we had more information. See comments above.

PS - Instead of a 12 your looking for a #8 or 6 or 4.

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