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I have a "Little Giant" condensate pump VCMX-20 model. This pump comes with a "safety switch". The pump turns on when the water level gets to 1.2 inches. The "safety switch" will "do something" when the water level reaches 2.2 inches.

Right now I don't have the "safety switch" connected... because I don't know how to connect the "safety switch". I want to connect the "safety switch" to turn off a wall outlet (used by a dehumidifier).

The manual is pretty short when describing the "safety switch":

  1. Safety switch: The safety overflow switch should be connected to a ClassII low voltage circuit. To control a thermostatic circuit the COM and NO connections from the safety switch are to be wired in series with the low voltage thermostat circuit to shut down the heating/AC circuit. The COM and NC switch contacts may be used to actuate a low-voltage alarm circuit (connected in series) if the heating/cooling system can not be disrupted. The safety switch comes from the factory with leads connected to the COM and NO switch terminals.

NOTE: When installing or replacing the safety switch, make sure that it is positioned between the two ribs on the motor cover (Figure 5).

For hook-up of NC circuits see Figure 5. figure-5

The "safety switch" has two wires hanging out.

I opened up the "safety switch" because the wires aren't labeled and found out there is:

  • one wire labeled "NO"
  • one wire labeled "COM"
  • one connector labeled "NC" without a wire
  • front
  • back

How do you connect the "safety overflow switch" wires to turn off a wall outlet??

The manual says to connect the "safety switch" to a "class-II low voltage" device. So maybe there is a "class-II voltage" device that controls the "wall outlet plug".

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You just need a relay that includes an integral 24V transformer. There are several of those on the market. By "market" I mean the market of products intended and listed for use in mains electrical; the ones I'm thinking of mount in a 1/2" knockout in a junction box.

You would probably want to move the safety switch wire to the NC position so that it contacts until an overflow. That way if it becomes disconnected it will fail safe.

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To expand on @Harpers answer (which is what I would do). What you have inside of your pump is what we normally call a dry set of contacts (a single pole double throw switch). Of course the "C" stands for common and "NO" normally open and "NC" normally closed. The switch contacts are only rated for voltages less than 50V. So the transformer is used for the control voltage and we install a pilot relay that has, in this case, a 24V coil and 125V rated contacts. This pilot relay is used to break the circuit wire to the wall outlet.

IDEC is a popular relay company that manufacture "ice cube" relays and you will need a base for it also, along with some sort of enclosure.

I don't know if this helps but I do hope it gives you an idea of how to make this work.

  • i am a beginner and so I am very grateful for the explanation of the "NC" and "NO" and your explaining what type of part this is "single pole double throw switch"... now that I know what kind of part this is and the terminology I can start working out the details... before I didn't really have enough info. I have a friend who is an electrician and maybe we can find something on amazon.com or some other vendor. – Trevor Boyd Smith Jun 12 '17 at 13:30

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