How to connect #8 AWG wire to a "standard" 20A GFCI receptacle?

Question

I'm planning to run a pair of NMWU cables to the backyard for an above ground pool. The pool pump + salt cell requires a 20 amp @ 120 volts circuit, and I calculated that an #8 AWG cable is required to keep the voltage drop below 3%; the run is about 190 feet. The second run of NMWU cable will only be #10 AWG since it only supplies a few 15A convenience outlets on the deck.

GFCI receptacles typically accept wires in the range of #14 - #10 AWG, so I'm wondering how to connect an #8 AWG to such a receptacle and still meet code (Ontario Electrical Safety Code to be precise)?

Answer 1

Voltage drop is very over rated for just about any residential application.

Of greater concern is the wiring method you are using; in the US, all pool equipment must be run in an approved and listed raceway, and have a properly sized grounding conductor run with it.

I am also not extremely familiar with the CSA Standards, but most 15 Amp receptacles that I've installed would not accept, nor would they be listed for use with, #10 conductors. This is big time overkill.

Again, depending upon the horse power rating of your pump motor; you may not be allowed to protect it with a GFCI device, it may require a GFCI circuit breaker.

Talk to the Electrical Inspector; ask him (or her) what the requirements are, and for any information they may be able to provide you with. Down "south" here, almost every Building Department has informational hand outs for pools, and most other projects. The Inspectors generally have a few more in their files, if you ask.

Again, I don't know about the Canadian Code, but I always point do-it-yourselfers to Article 90.1(C) of the NEC and tell them that what the Code means to say, if it were not edited by lawyers, is that this ain't no instruction book, and electricity kills people every day. Water and electricity are a deadly combination. Consider hiring a qualified pro.

Good luck.

Answer 2

I'm not sure about the Ontario Code, but the US NEC allows you to splice a piece of #10awg onto the end of the #8 since its being used to control voltage drop rather than amperage. Just use a "wire nut" connection in the outlet box.

Answer 3

if you are using the 8g only for the distance, and not required for the pump, you could add a weather-tight disconnect box in the line outside which will accept the 8g. run 10g from there to panel.