Wiring a 120 volt device to a 240 Pool Timer

[benavidescj]

I have a 120 volt acid pump that I need to hook up and want it to run with the pool pump. The problem is the timer is a 240 volt timer (see diagram). Can I hook up the black wire to lug 2 or 4 on the timer and the white wire to the neutral bar to get the 120 volts I need and still run with the timer?

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[Bama Rambler]

You can do it exactly as you describe. Just bring one leg off either 2 or 4 and one from neutral to the pump and you're good to go.

 

[PoolGuyNJ]

While what 'bama said should work, I will discourage this. This puts an uneven load on the hot leads from the circuit breaker. That can create a situation that prevents a circuit breaker from tripping properly, a serious fire risk.

Putting the feeder on it's own connection and timer at 120V or getting a 240V feeder is the safe way to get this done.

Scott

 

[benavidescj]

Awesome, thanks for the quick reply. Unfortunately I asked the question after I burned up the motor by attaching wires to lugs 2 and 4 . I was going to try and replace the parts I burned up, but I think I am going to try and get a 240V feeder to be safe and try again.

 

[Bama Rambler]

Circuit breakers are designed to trip even if one leg has zero current flowing through it and the other leg is seeing current above the trip rating. Unbalance on the circuit won't affect the safety of the device. You are creating a small unbalance but those injection pumps draw such a small amount of current it won't be enough to cause a problem. Even at 120 volts you're talking less than 2 amps for one of those little pumps.

 

[benavidescj]

The manual says that the max current draw is 2.5 amp. I will check to see which motor costs more. My guess is that the 240V version is more expensive. By the way, all this equipment is outside in NEMA 3R rated enclosures on a brick wall. If something happens at least I have some protection. If the price is not much different I am going to go with the 240V version.

 

[Ohm_Boy]

By the way, all this equipment is outside in NEMA 3R rated enclosures on a brick wall. If something happens at least I have some protection.

The breakers aren't there to protect the device. They actually only protect the upstream wiring system FROM the device.

As for the imbalance, yes - double pole breakers are designed to trip if even one side sees an overcurrent or short, but it is always best to maintain a balanced load on them. The pole interlock is a mechanical function, and some have been known to fail. I've actually seen 240v breakers with one side tripped. More common on clothes dryer circuits than you'd think. Also, clothes dryers use one side for 120v for the controls...