Electrical – Wiring Pool Subpanel for Pump and Receptacles

electricalpoolsubpanelwiring

The project is to wire a sub-panel and three pool circuits. My 400A main panels (2) are about 35' away, and I don't have room inside the basement to mount the sub panel inside. I plan to use an Intermatic PE20000 60A outdoor load center (or a fancier PE25065RC that includes remote controls), and I will mount this on the outside of the house about 40' from the main panels. The load center will have three circuits to feed a 1.65HP 230V variable speed pump and two (2) 15A receptacle circuits (lighting & convenience).

Misc:

  • Location is Virginia
  • 14'x33' fiberglass in-ground pool located ~40' from house and sub-panel
  • Hayward SP2303VSP pump (230v variable speed)
  • No heater or other powered equipment
  • Lighting circuit will supply (2) 12v transformers for (2) LED pool lights
  • Convenience receptacle is required within 20' of the pool edge

I would appreciate any guidance on the following:

Main panel:

  • 30A 2-pole GFCI

Sub panel (Intermatic PE20000):

  • 15A 2-pole breaker (non GFCI) (pump)
  • 15A 1-pole (non GFCI) (lighting recept)
  • 15A 1-pole (non GFCI) (convenience recept)
  • Non-bonded neutral and ground
  • No additional ground rod

Wire from main to sub:

  • (4) #10 THWN-2 copper stranded (~40' runs)

Wire from sub to circuits:

  • (3) 12' #10 THWN-2 copper stranded from sub panel to 230v pump (L1, L2, ground) in watertight conduit (#10 to future proof the wire)
  • (3) 60' #14 THWN-2 copper stranded from sub panel to 120v lighting receptacle (L, N, ground) via 3/4 schedule 80 PVC
  • (3) 100' #14 THWN-2 copper stranded from sub panel to 120v convenience receptacle (L, N, ground) via 3/4 schedule 80 PVC
  • All 3/4" schedule 80 conduit buried at 18"

Equipotential bonding: ~300' of #8 THWN-2 copper solid (bare) with equipotential connections to:

  • 3' horizontal under pool coping/pavers around pool perimeter
  • deep end stainless steel ladder anchor plate
  • 230v pump ground (it's not double-insulated)
  • bonding electrode within PVC at pool filter
  • not bonded back to the sub panel

Specific questions:

  • Is the #14 THWN-2 feed from sub panel to 230v pump sufficient (10FLA)? Consensus is yes per the pump manual

  • Are the #14 THWN-2 20A circuit feeds sufficient for those lengths (90 deg THWN-2 #14 copper should be 25A)? Consensus is yes

  • Does my #8 solid equipotential ground need to connect back to the sub-panel, or is the connection at the pump sufficient to tie back to the main ground? Not back to the subpanel – just to the pump.

Any recommendations for making things cleaner?

Best Answer

Wire from main panel to subpanel is protected by the breaker in the main panel. So its size is decided by the breaker.

  • 30A means 10AWG Cu
  • 40A means 8 AWG Cu
  • 60A means 6 AWG Cu / 4 AWG Al
  • 70A means 4 AWG Cu
  • 80A means 3 AWG Al

All these numbers for <100A feeders come out of table 30.15(b)(16) working out of the 60C column because of NEC 110.14(C)(1)(a). Nobody is going to recommend working out of the 90C column, and the inspector is unlikely to approve it.

Additionally, #10 Cu wire will be limited to 30A because of 240.4(D)(7).

You are welcome to use #14 copper wire to lighting or convenience receptacle branch circuits. It must be breakered at 15A due to 240.4(D)(3).

If you want to breaker it at 20A, then use either #12 copper or #10 aluminum.

Although 240.4(D)(6) allows 25A on #10 aluminum on receptacle branch circuits, use of a breaker other than 15 or 20A is outlawed by Table 210.21(B)(3).

Your expectation of being able to work out of the 90C column is weird. That's generally not allowed. Generally in <100A circuits you must work with the abovementioned table, plus

  • 15A means 14 AWG Cu.
  • 20A means 12 AWG Cu.

There is an exception in Code for certain large motor loads on dedicated circuits, which allows an enlarged breaker. This is to avoid nuisance trips and has nothing to do with wire thermal rating, to which 240.4 still applies. One of us is an expert on this clause and hopefully will discuss it. However, using this exception draws a lot of heat from inspectors and you will often need to defend the choice.

However, 110.3(B) still bears force: If the labeling or instructions for the motor, breaker or panel requires the larger wire, you must use it; end of subject!

I personally would use EMT conduit for distribution past the subpanel. I also think use of #14 is a mistake.

As things are, you will need to buy 6 wire sizes and colors: Black, white and green #12; and black, white and green #14. That's six spools, what a waste of money! I use EMT conduit and would buy only black and white #12. EMT provides the ground. Actually, I own 10 colors of #12 and no #14. The price difference 12-14 isn't worth it.

Lastly, it is far past time to talk about GFCI. GFCI protecting the pump would not be a bad idea. The other circuits require it. You may be reluctant to protect the pump since the cost of all these GFCIs is really stacking up. However you can protect them all with one GFCI device: Either

  • a GFCI breaker in the main panel that feeds the subpanel (about $90) or
  • a "hot tub" subpanel which includes GFCI protection onboard. Obviously it will need enough spaces to support the pump and lighting/recep circuits. One option is a 2-space "hot tub" subpanel that supports a quadplex breaker. (not all brands do).
Related Topic