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

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)?

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lemonie7 years ago
Like steve' says, but with an example diagram:

NiekZ (author)  lemonie7 years ago

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!

lemonie NiekZ7 years ago
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?

NiekZ (author)  lemonie7 years ago
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.

lemonie NiekZ7 years ago
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.

NiekZ (author)  lemonie7 years ago

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

NiekZ (author)  NiekZ7 years ago
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