What I mean by one way relay is manually reset it to run again. What I need it for:

I want a pump to run when a relay is on(manually turned on), when there is no power the relay trips and stays like that in off position. Because even if the power comes back on I don't want the pump on. Until I reset the relay.

I keep saying a relay, but it doesn't have to be. Anything that could handle 240V. Is there anything I could use for this?

  • \$\begingroup\$ It is called a latching relay and can be made from any relay with two sets of contacts. try google. \$\endgroup\$ Feb 1, 2021 at 1:46

1 Answer 1


This is a very common requirement for machine controls. You can buy switches with this function built-in - Look on Amazon for "motor safety switch".

A typical DIY circuit is:


simulate this circuit – Schematic created using CircuitLab

  • \$\begingroup\$ Beat me to it... \$\endgroup\$
    – Mattman944
    Feb 1, 2021 at 1:55
  • 1
    \$\begingroup\$ An NVR switch should do it then. \$\endgroup\$
    – Che Jug
    Feb 1, 2021 at 2:44

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