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How can I start/stop a waterpump (230V 500Watt) using a magnetic floating switch which can switch 230V max 1A 15W? Answered

I have a cleanwater pump in my cellar 230V / 500W to keep the floor almost completely dry.
I have a liquid level sensor that can switch max 250 volt, max switching current 1A, and maximum switching power 15 Watts.

I don't know enough about electronics to know how to fix this problem. But I do know that the switch won't work when I connect it directly to the pump...

So how can I get this working (low cost)?



Best Answer 8 years ago

Like steve' says, but with an example diagram:



All three anwsers are very helpfull!

The tutorial is also very usefull fo rme.

So, correct me if Im wrong, but although the switch can handle 230volts, I have to use a low voltage supply for the relay.

Thanks a lot!

The switch can handle up to15W providing the supply is less than 250V and less than 1A. You could get a 230V-powered relay but I think it would be a bit harder to find and more expensive. See what you can find and what they cost?


Okay, I found this one: cheap, in stock, up to 250V 12A max 3000VA. (so i can also use my water-vacuumcleaner (1600Watts))

It's a dutch site, but you can find the link to the english data on the right.

If I need to use a low current switch, I also need to buy a power supply. So the 230/250V solution will be cheaper.
I'll also need a socket for the relay, which 'll cost about € 2,60. Cheap enough.


Seems OK (just looking at it), go with that then. Be careful with the electrics. That one appears to not need the low voltage supply.


When I made it, I'll post the results.
Probably by the end of this week.

The circuit works!
See the picture. I tried to make it look nice.
I tested it using a bulb, and it lit when it had to.
Now I only have to make a cover and hang it in the cellar.
Thanks for the help.


Use a relay. You can get a low voltage supply -like a Wall wart to run it via the switch, the contacts then switch your pump - get a  nice fat relay and it'll switch forever - don't mess around with something "near" 500W (2A) get a 10A or 25A rated one - still less than 15 euro I'd guess.

This tutorial helps explain how a relay can be used like this