Float switch for DC pumping?

[BryanB]

Can someone recommend a float switch for a DC system? I have a Shurflo 9325 submersible pump with 902-200 controller, and a 100w 24v solar panel. The distance is about 300' from the controller to the storage tank, also what wiring would I use? I want the pump to turn on when the water level goes down to a certain point.

Thanks!!!

[PNPmacnab]

Use a relay to control the pump. Running high currents the length of that is not practical. This also allows you to use a low current float switch.

[BryanB]

Use a relay to control the pump. Running high currents the length of that is not practical. This also allows you to use a low current float switch.

Ok, could you please explain more? How does it work, can you recommend a low current float switch? What exactly is the relay?

[Mike90250]

Well, you got to have some electrical knowledge on relays, powering them, and contactors. I use a relay to control a contactor (all a contactor is , is a heavy duty relay for motors). My tank and float switch is 160' elevation up a hill, but a 1,000 foot cable run, so I use a AC relay to control the contactor. I use 120VAC, but because a relay has very little current consumption, there is little to no voltage drop over that distance.

You would have to examine float switches to see if they are rated for DC circuits.

[BryanB]

That is part of my problem, Mike, I have very little electrical knowledge, but am trying to learn. I did find a float switch which works on DC, but the company informs me that it isn't for potable water:

https://www.floproproducts.com/upload/sje_milliampmaster.pdf

[PNPmacnab]

It says,
Passed NSF Standard 61 protocol by an approved Water Quality Association laboratory.

This is the interesting one.
Low current, non-arching applications down to 0.160 mA at 125VAC

A friend had these on his low voltage control septic system and has to replace them about every five years. They need higher voltage and sufficient current to prevent an oxidation layer from forming on the contacts. They can always be fixed by connecting to a lamp and making contact a few times.

If I was doing this I'd just buy a 500' roll of single conductor #14 and use ground as a return. If ground resistance can be under 1K ohms, it would be workable.

Google is your friend. Just keep reading and you will learn. Forums are the worst way to learn anything.

[BryanB]

Forums are the worst way to learn anything.

Ok, thanks for the advice!!!