Remote switch to select between two 10HP well pumps

Joe T. · Nov 8, 2018

I have a simple task. I have 2) 10hp 240V well pumps. One is a backup pump if the primary pump fails. My desire is to have one control box send current to the pumps 150 feet away. Before the pumps I would like a “selector” switch to send power to the pump of my choosing. I would like to have this switch remotely controlled from my office.

The goal is to have one float system communicate with the pump to control the water level in the holding tank. Should there be a pump failure, I flick a switch in the office, and the secondary pump resumes the job. I run one control box and set of wires to two pumps instead of two sets of everything. I cut the wiring cost in half and my boss builds a shrine in my honor while doubling my salary! One can dream can’t he?

A switch, relay, contactor, MUST exist for a job like this. How do I find it?

Fredson · Nov 8, 2018

You’d need need two appropriately related contractors for the pumps, or a single double throw unit. But this scenario to me kind of begs the question of why? The control box is just as likely if not more so to fail then the motor. I assume it has a starting relay and capacitor(s)? If so that is where your failure is more likely. Both pumps on one starter box gets rid of a lot of your redundancy. Better option would be one feed to two starters at pumps.

wheels17 · Nov 8, 2018

Put the second pump on a second float switch set lower than the first. As long as the first pump is operating properly, the second switch never operates. When it fails, you don't even have to flip a switch system just runs in a slightly lower level.

Rob F. · Nov 8, 2018

You can (should) use an alternating relay. It would be control for motor starters. This will change pumps every time one is needed. This will keep both pumps running so one does not get forgotten about.

DDoug · Nov 8, 2018

Put a PLC on it, and make it doo whatever you want, easily changeable
after install...tappity, tap, tap. Reprogram it on the fly.

Eliminate the operator (you) and the boss will really be impressed....

Joe T. · Nov 8, 2018

Fredson said:
You’d need need two appropriately related contractors for the pumps, or a single double throw unit. But this scenario to me kind of begs the question of why? The control box is just as likely if not more so to fail then the motor. I assume it has a starting relay and capacitor(s)? If so that is where your failure is more likely. Both pumps on one starter box gets rid of a lot of your redundancy. Better option would be one feed to two starters at pumps.

The pumps are in a humid environment and I am looking to place the control box (as you expect, relay and capacitors) 150' away in a dry building. I would like to run 1 set of wires to the pumps. It seems like you and I are basically suggesting the same thing.

Joe T. · Nov 8, 2018

wheels17 said:
Put the second pump on a second float switch set lower than the first. As long as the first pump is operating properly, the second switch never operates. When it fails, you don't even have to flip a switch system just runs in a slightly lower level.

That would require two independent systems. I'm looking to share the control box and feed wires.

JST · Nov 8, 2018

Joe T. said:
That would require two independent systems. I'm looking to share the control box and feed wires.

If you have two pumps at a distance, and want all the controls in one box far from the pumps, AND you want to share feed wires...... Just how do you propose to control which pump is working?

It seems you either need two sets of wires, or you need to put the controls at the well location. You need a set of wires from each pump to some sort of control box that "decides" which pump should run, and applies power to the wires to that pump.

There are NEMA boxes for all sorts of environments, so you can put a weatherproof box at the pump location with the controls in it. One power line to it, and, at worst, a control line (low power) from there to wherever you want to put the actual controls that a person needs to touch.
I

Ziggy2 · Nov 8, 2018

Joe T. said:
That would require two independent systems. I'm looking to share the control box and feed wires.

I think you are trying to be too cheap on this one. You have a backup pump for the main pump and want to be able to switch over rapidly and easily if the main pump fails.

It is highly likely with this approach that the standby pump will fail when you need it and attempt to use it. In the real world this approach is often less reliable than just a single pump in that with the presence of a backup pump there is a false sense of security in the presence of the backup pump yet nothing is done on either pump to ensure that the system will work when needed.

There is a reason why dual pumps are setup as a duplex pumps. Both are being used and proven with operation.

Your plan of sharing the control box and feed wires further reduces the system redundancy in that a failure in either of these will render the whole system unusable.

If the economic value of having a pump running to maintain water level in a tank justifies having a backup pump, then your plan should be able to have a budget to support doing the job correctly to actually have the required redundancy.

Anything less will be folly.

Joe T. · Nov 9, 2018

If you have two pumps at a distance, and want all the controls in one box far from the pumps, AND you want to share feed wires...... Just how do you propose to control which pump is working?

My first post states I want a switch that I can control remotely. I could simply have a disconnect at the pump and manually switch the wires from one pump to the other. All I want to do is that without getting out of my chair.

In the end no matter what fails I'm going to be walking down to the pump to fix it. A transfer switch like used to switch the power line to a generator does the same thing except that has two power inputs and one output (the house). I want the opposite. One way in and two ways out.

LKeithR · Nov 9, 2018

150 feet? Holy crap! Just walk over and turn the damn backup pump on. Can't be that big a deal...

SteveBausch · Nov 9, 2018

Mechanically interlocked reversing contactor.

Just need to rethink the wiring, a bit.

Don’t “reverse” either motor.

Each contactor supplies its respective motor.

eBay - Page Not Found

If the big contactors are already in place, the reversing contactor will control the coil of each motor’s contactor.

Regarding transfer switches, manual units don’t care which way the current flows, but an automatic switch WOULD require the current flowing from one of two inputs, since the inputs are monitored for voltage.

Your 150 feet of control wiring is exempt from voltage drop calculations. As long as the relays/contactors work, you are golden.

The real issue is: single phase or three phase?

If the motors are single phase, you’ll most likely not find a suitable contactor; a smallish reversing contactor will need to have two very large contactor capable of surviving the inrush.

SteveBausch · Nov 9, 2018

LKeithR said:
150 feet? Holy crap! Just walk over and turn the damn backup pump on. Can't be that big a deal...

This is for the family members, not him.

I suspect.

Joe T. · Nov 9, 2018

SteveBausch said:
If the motors are single phase, you’ll most likely not find a suitable contactor; a smallish reversing contactor will need to have two very large contactor capable of surviving the inrush.

This is beginning to sprawl into a more difficult task then I had hoped. They are single phase motors. I'm not looking for a re-invent the wheel task that will burn up time. If my plan is destine to be plagued with reliability issues, I'll swap wires manually. The only failure we have ever had was in the control box due to moisture.

Thanks for the insight.

Joe T. · Nov 9, 2018

SteveBausch said:
This is for the family members, not him.

I suspect.

Yes. I'm setting up a "clean slate" system for the new generation of clueless family members. The current system is chock full of Rube Goldberg inspired systems stemming from "it was already here" mentality.

JST · Nov 9, 2018

If you CAN accept a new box by the pumps, then two contactors (one per pump) in a box at the pumps, and a remote switch to do the changeover. Simple, should be as reliable as one, gives you the switch, does not bother the existing control box, one power line to the pumps.

.

Rob F. · Nov 9, 2018

Joe T. said:
A transfer switch like used to switch the power line to a generator does the same thing except that has two power inputs and one output (the house). I want the opposite. One way in and two ways out.

Manual transfer switch wired "backwards" will do it but you still walk to throw the switch

Larry Dickman · Nov 9, 2018

I found a relay for my pump at an irrigation supply house.

Joe T. · Nov 9, 2018

Rob F. said:
Manual transfer switch wired "backwards" will do it but you still walk to throw the switch

May be the least annoying resolve. One way or the other I'll be there for repairs. This has not been a chronic issue in the past. Just looking to build the better mouse trap.

Thanks.

Rob F. · Nov 9, 2018

sewage tanks with grinder pumps usually have 2 pumps with an alternating control on them. That could also work but where do you mount the control box.
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Remote switch to select between two 10HP well pumps

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