Float Switch Wiring

Discussion in 'General Equipment, Hardware, Filtration' started by BigHildy53, Nov 14, 2017.

  1. BigHildy53

    BigHildy53 Active Member R2R Supporter

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    My RO/DI unit has booster pump built in. I want to use a float switch to turn the pump off when the water reaches a certain level. The float switches at BRS come with bare wire. How do I wire that into something that will turn the pump off. Something about a relay switch?
     
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  2. Grey Guy

    Grey Guy Well-Known Member

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    I would suggest getting an electrician to help you or buy something already made to do what you need it to do.
     
  3. BigHildy53

    BigHildy53 Active Member R2R Supporter

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    Probably best I buy one with a piggyback connection. But I thought I had to try DIY, and mess that up, before going the more logical route, for me that is.
     
  4. ithk21620

    ithk21620 Active Member R2R Supporter Build Thread Contributor

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  5. saltyfilmfolks

    saltyfilmfolks Lights! Camera! Reef! R2R Supporter R2R Excellence Award Reef Squad Leader Photo of the Month Award Build Thread Contributor

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    A float switch is a single wire circuit interrupt.

    So you have two wires on the float. place the switch in one of the wires.

    It breaks the circuit.
     
  6. ithk21620

    ithk21620 Active Member R2R Supporter Build Thread Contributor

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    This is true but you don't want to use a float switch for a pump directly. They are not rated for the loading of a pump.

    From the BRS Float switch description:
    "
    A pump rated at just 5 watts can destroy a float switch rated for 50 watts, locking it in the “on” position and pumping a lot of water where you do not want it.

    The magnetic reeds enclosed in liquid level sensors are extremely reliable and long-lasting when utilized properly. Failures are nearly always a result of current overloading. Pumps, solenoids and many other devices that require control by a liquid level sensor carry "steady state" current ratings. These devices can draw ten times (or more) their steady state power ratings on start-up or shut-down. When the reeds inside our switches are exposed to this kind of "spiking voltage" they can overheat and become deformed. In some cases they may even weld together or break off, causing the switch circuit to remain closed (or open) regardless of the level of the float. Deformed reeds can also function intermittently, causing problems with troubleshooting. A 50 watt float switch can be destroyed by a pump rated at 6 watts and, unfortunately, it may take many cycles before the failure occurs.

    Because they can destroy an otherwise very reliable float switch, care must be taken to completely isolate the switch from the current drawn by pumps, solenoids or other devices subject to spiking voltage. Resistors or diodes may be used, but the most common solution is to utilize a circuit board or a relay.

    In the illustration, a relay acts as a switch for a pump, thereby isolating the float switch from any spikes that the pump may draw. The float switch turns the relay coil on and off. In this way, the only current handled by the float switch is that small amount required by the relay coil. Please consult with your relay supplier to assure that the relay current requirements are well within the specs of the float switch."
     
  7. saltyfilmfolks

    saltyfilmfolks Lights! Camera! Reef! R2R Supporter R2R Excellence Award Reef Squad Leader Photo of the Month Award Build Thread Contributor

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    I wonder why mine aren't broken.

    I must have used the right one.
     
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