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State is Florida. I am wiring a continuous run non-submersible irrigation well pump. I am using a 30A breaker with #10 THHN in Sch 40 PVC conduit buried 18". I could have gone direct bury but I feel safer in conduit in case either me or the next homeowner dig.

I have a pump start relay that is controlled by a rain bird sprinkler controller. The controller is all the way in the garage. Since the sprinkler controller is far away I want to wire in a simple switch in parallel so I can flip the pump on if needed (I have a hose on it, need to test it, or something). Since I'm going through all this trouble I might as well give myself an outlet.

My questions are:

  • Are parallel circuits allowed per code @ 220V?
  • Am I correct in bonding the neutural and ground since this is an outside panel. I assume I still need to run a neutural for my GFCI.
  • Is there a better, cleaner way to do this? Perhaps a small 24V transformer on a switch?
  • How many splices am I allowed? I would assume splices have to limit something. Can I splice 4 wires into a splice w\ wire caps?
  • Is it ok to use stranded THHN? That's all home depot had.

Here is my wiring diagram.

https://i.sstatic.net/OhRII.png

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  • I think you should put another sub panel where the GFCI goes and another 30 amp breaker + a 15 amp breaker. Then the GFCI is done right. Most of what the Depot sells is THWN/THHN so your good on the wire probably
    – Kris
    Commented Jan 17, 2017 at 21:55

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The bad news

You can't run the GFCI outlet off of one half of the branch circuit as you propose, as it's illegal to put a 15 or 20A receptacle on a 30A circuit. (The receptacle itself isn't protected properly against overload in that case.) You'll need to scrap the receptacle, or put it on a different circuit/run.

The other problem you have is providing a disconnecting means for the pump -- right now, the only disconnecting means for it is the branch circuit's breaker in the panel, and in order for this to be Code, the pump location needs to be in sight of the panel as per 430.102(A) and (B). Otherwise, you'll need to toss a disconnecting means for the motor and controller into your box instead of that GFCI you wanted to stick in the 3rd gang, and clearly label both switches as to their function.

The good news

In turn:

  • Article 404 won't stop you from connecting switches in parallel like that at any voltage, provided everything's running off the same branch circuit and the switches are being used within their ratings.
  • Leave the panel bonding in its current state (i.e. bonded for a main panel, unbonded for a subpanel).
  • You can put a SPDT (3-way) switch on the 24V side as Harper describes provided you have a spare low-voltage wire to bring 24V down to the pump location.
  • There is no limit on splicing as long as the individual splices are made in accordance with 110.14 and the box fill is not exceeded
  • Stranded THHN is not a problem as long as the terminations are rated for stranded wire
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Switch the relay on the 24V side

Got extra wires in your thermostat cable? Right now you have switched call-for-water and common. Bring over 24V also from the transformer, and add a 3-way switch: common is the relay, one traveler is the call-for-water from the sprinkler board, and the other traveler is 24V.

Wires and nuts

Stranded THWN is delightful stuff to handle, and the only thing I use. Occasionally you run into terminations that are not listed for solid wire; pigtail or get better devices.

Barely relevant since most THHN is THWN these days, but you must use THWN in wet locations. That's the W.

Wire nuts are listed for certain combinations of wire. Those combinations were nominated by the manufacturer based on testing, and sent to UL or CSA who tested them again. Somewhere on the web is a sheet listing all the allowable combinations for that make/model. The allowed range is impressive to the point of unnerving.

A 120V receptacle on a 240V-only circuit

You can't put a 120V receptacle on a 120/240 circuit that also serves a 240V load. (i.e. it either serves a load, or it's a MWBC.) You also can't put a 20A receptacle on a 30A circuit.

If you want a receptacle there, you need to pull a separate hot and neutral (you're pulling neutral in any case). Must be a 120V breaker, 15A (14-10 AWG) or 20A (12-10 AWG). Don't buy 14 AWG, buy 12 instead - otherwise you're stuck with a partial reel of 14 AWG then have to spend $45 on another reel for the next 12AWG project, have to store 2 reels, and check constantly to make sure you got the right reel.

Neutral vs Ground

"Outdoor" has nothing to do with it. Neutral is bonded to ground in precisely one place: the main panel. It is always best to connect neutral and ground to their separate bars, to cultivate right thinking, and so that panel can be easily converted to a sub-panel, or the ground bond can be easily removed for testing. However it is legal to slather them all onto the same bar in the main panel only.

I generally find outdoor panels fail quicker than expected, and outdoor receptacle covers only collect water. I like to build little birdhouse style cabinets over them to keep the weather off them. This may not be strictly code. Make sure it remains practical to get the covers off etc.

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  • Actually, you can have a MWBC that also serves 240V loads IF the overcurrent device opens all the hots simultaneously (this is Exception 2 to 210.4(C)).
    – ThreePhaseEel
    Commented Jan 18, 2017 at 0:21

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