Relay (prefer just DPST) to control 230v (singlephase, 2 hot) 12 amp well pump.

Hi all. Trying to make up a solid state well pump controller using an arduino and keep it as simple as possible.

I can find directly controlled relays up to a 10A contact rating, but will be using a 2hp pump, and it draws 12A...

Looked through tons of sites and can't find any that will handle that amperage with low enough coil draw to directly control with arduino. Was looking mostly for 15A rating so it wouldn't be at max rating.

Want to keep it as simple as possible. Could add basically a relay to control the relays type of thing, but trying to avoid that if possible.

Any suggestion on finding a relay that will work? Or just break down and have to add some hat that could feed more amps to the relay coil?

FYI: 12A -it is a deep well pump, and is 2HP motor on it!

That's a serious pump at 12A. Look for a 'contactor' which is the industrial version of a relay. There are many coil & contact variations. You'll need to check the coil specs of the contactor - to figure out the best way of driving it (many/most have AC driven coils).

It's easy to find [u]industrial solid state relays[/u] that can be controlled with 5V / low current. They usually have screw-terminals so they are super-easy to wire-up and they are also easy to mount. But, since they are usually SPST, you'd need two of them to switch two "hots". They are more expensive but you don't have to buy/build a driver circuit.

If you use a regular electro-mechanical relay, you'll need a transistor or MOSFET [u]driver circuit[/u], circuit, and probably a 12 or 24VDC power supply.

You can get "relay boards" that have a driver & relay built-in, but I don't know what you'll find with a 12A rating.

Most of the combined driver/relay modules on eBay /alibaba etc do NOT meet electrical isolation standards for mains voltage switching. They'll work fine, but safety is marginal at best. Check your fire & liability insurance.

Careful. And ensure any mains earthing is properly bonded to spec!

Hard finding double pole - Would it work using two of the relays below? Just write high to two pins - (one pin for each relay to make sure they don't over draw?)

Plenty of DPDT 30Amp relays with 12volt coils and spade terminals on ebay. Add the transistor/resistor/diode yourself. Power relay and Arduino from 12volt. Leo..

...will be using a 2hp pump, and it draws 12A... Was looking mostly for 15A rating so it wouldn't be at max rating.

That's just the running amps, you're missing what it requires at start which could be more than 60 amps. IMO, this is NOT an application for solid state relays.

It looks like you are in the US so yes, phase wires going to the pump must be switched, they are each 120vac to ground. It is required by code and as a benefit, it lessens the chances of relay contacts welding and the pump staying on. Does your overpressure device dump the water in a drain or all over the floor somewhere? Most are right at the tank and if it vents, it will go everywhere... at pressure!

I've had a pair of these running a 1hp pump, 240 feet down, running for several years without issue. There is a 100psi transducer feeding an UNO for control.

While I built the system for winter related well freezing issues (story for another day), the side benefit is better control of my domestic water system that I could not achieve with a mechanical switch. I have my operating range set to 40psi turn-on/50psi turn-off. This was originally done to provide better shower flow on the second floor but the unforeseen benefit turned out much better hot water generation with a 30 year old oil burner with a summer-winter hot water coil. The increased the pressure increased the hot water efficiency due to the higher pressure in the heat exchanger coil. The net result was that I was able to reduce my boiler firing temperature, saving about 30 gallons of oil a year, roughly a 5% savings. Totally unexpected!

Edit: Just had a scan through eBay looking for Leo's suggestion above. Time to replace what I have with one of the below, it's a far cleaner solution:

Yeah, just was hoping to be running from a single power supply. And it is an irrigation system, so the OP valve vents out the pump house.

Want to use a RasPi as a sprinkler controller, so will need a 24vAC for the valve control. So trying to not get a control box full of power supplies/transformers!

So best answer may be to use teh 24VAC power supply and AC/AC relays and then have the arduino control relays to cycle 24V control circuit. Then have the 24VAC needed for sprinkler valve control, and can use a transformer to make a 5vDC circuit to power the silicon. And the relays for the sprinkler valves would be same as the uno control of the AC circuit.

A bit more complicated than I was hoping for, but it seems like it might be most efficacious.