Storage-Tank Kit Float Switch Wiring: Identify the Wires with a Multimeter and Test Continuity

"The float switch wires on my storage-tank kit don't match the diagram. How do I know which wire is which?"

Answer

Identify the switched pair by behavior, not by color. Wire colors can vary between batches, so the reliable way to find the right leads is a multimeter continuity test: with all power disconnected, watch the meter while you move the float by hand through its full travel. The pair of leads that changes between continuity (closed) and no continuity (open) as the float rises and falls is your switched pair.

Whether continuity is present when the float is up or when it is down tells you whether the switch is normally open or normally closed. Once you know the switched pair and its behavior, you can wire it into your control circuit correctly.

A quick refresher on what a float switch does: it tells the pump or system when the storage tank is full (stop filling) or empty. It is essentially a simple switch that opens or closes a circuit as the float rises and falls. A normally open switch closes the circuit when the float rises; a normally closed switch opens the circuit when the float rises. You need to know which behavior you have and which two leads are the switched pair.

Safety / before you start

ELECTRICAL SAFETY WARNING - READ FIRST

• Disconnect and lock out all power to the pump and system before touching any wiring. This is non-negotiable.
• Water and electricity together are dangerous. Keep the work area dry and keep your hands dry.
• If you are not comfortable working with low-voltage wiring, or if the system is hardwired to mains power, stop and hire a licensed electrician or plumber.
• Always follow your local electrical code.

Do not proceed past this point until power is fully disconnected and confirmed off.

Steps

1. Disconnect ALL power to the pump and system first. Confirm it is off. This is non-negotiable.
2. Set a multimeter to continuity (the audible beep, or the ohms setting).
3. With the two switch leads disconnected from anything else, touch one probe to each lead.
4. Move the float by hand through its full travel (lift it, lower it). Watch or listen to the meter: continuity present in one float position and absent in the other identifies the switched pair, and tells you whether it is normally open or normally closed.
5. If there are more than two wires, test pairs to find the pair that changes state with float movement. That is the switched pair to wire into the control circuit.
6. Wire the identified leads per your system's control input, restore power, and test a full fill/stop cycle.

A note on color: because wire colors can vary by supplier batch, identify the switched pair by behavior (the continuity test), not by color.

When to contact support

Reach out to our support team if:

• You have more than two leads and are unsure which pair is the switched pair after testing.
• You see no continuity change in any float position (this can indicate a defective switch).
• Your system is hardwired to mains power rather than low-voltage control.
• You feel any discomfort working with the wiring at all. We would rather help than have you guess.