How to Install the Rule-A-Matic Float Switch

Written by alisa stevens
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The Rule-A-Matic float switch to the bilge pump provides boat owners with a safety precaution. The bilge pump empties the boat of water to prevent it from sinking. Normally, the crew manually turns on the pump. Installing a Rule float switch provides extra coverage. The float switch detects when the water in the boat rises to a certain level, then automatically turns on the bilge pump. In this situation, the pump empties the water from the boat even if the crew is not aboard. Once the pump finishes emptying the water, the switch turns it off.

Skill level:
Moderately Challenging

Things you need

  • Rule-A-Matic float switch
  • Three-way switch
  • Cable clamps or ties

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  1. 1

    Remove the power source from the pump by detaching the negative wire from the threaded post of the boat's negative battery terminal.

  2. 2

    Put the Rule-A-Matic float switch near the bilge pump. It should be level or slightly higher than the pump to prevent it from turning the pump on too early.

  3. 3

    Attach the Rule-A-Matic float switch to the hull. Review the float switch mounting instructions since they can vary by model.

  4. 4

    Route the Rule-A-Matic float switch wiring to the bilge pump manual control switch. Run the wiring along the side of the boat, away from the main walkways. Avoid areas that are consistently wet. Fasten the wire down every 18 inches using the cable clamps or ties.

  5. 5

    Remove the pump manual switch and insert the three-way switch. Attach the power wire to the three-way switch's line terminal. Connect the bilge pump's old manual wire to one of the switched terminals on the three-way switch. Fasten one of the Rule-A-Matic float switch wires to the remaining switched terminals on the three-way.

  6. 6

    Reattach the negative cable on the bilge pump to the battery's negative terminal.

  7. 7

    Test the connections to the three-way switch. Put the three-way switch in the "Off" position. Move the switch into the automatic position. The pump should remain off. Flip the three-way switch to the manual position. Confirm after each change that the pump remains off. With the switch in the automatic position, pour water into the boat. Once the water level passes the Rule-A-Matic float switch, the pump should turn on and drain the boat. The three-way switch should remain in the automatic position.

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