Frequently Asked Questions

How do float switches work?
What will cause float switches to fail?
Are the float switches you sell reliable?
If a float switch fails, will if fail in the “on” or “closed” position?
Can the float be reversed to change the switch function?
Do float switches require maintenance?

How would I use the switch in an auto top off application in an aquarium?
How much of the switch will be below the liquid level?
Can a float switch be completely submerged?
Why do you sell the Maxijet 600 over the Maxijet 400, 900 or 1200?
What are your shipping procedures and charges?

How do float switches work?

See How Float Switches Work

What will cause float switches to fail?

Overloading float switches is the usual reason for failure.

Wiring a 15 watt pump or other device through a 50 watt float switch can still lead to overloading. See Curing Spiking Voltage with a Relay for crucial information about safeguarding your float switches from failure.

Are the float switches you sell reliable?

Yes. Float switches use tried-and-true reed switch technology which has been in use for decades. The switches we sell should be good for many thousands of on/off cycles if used properly.

If a float switch fails, will if fail in the “on” or “closed” position?

If you overload a float switch, it can fail and this would normally happen in the on position. The internal reed gets very hot, melts and fuses together, disabling the switch’s ability to break a circuit. No device is 100% fool proof. If a failure in the on position would be disastrous in your application, we suggest using two switches in series, so that one acts as a back-up.

Can the float be reversed to change the switch function?

Our switches come normally closed – i.e. the wires complete a circuit when the float is at rest and break it when the float rises. To change them to a normally open state (so that the wires will break a circuit when the float is at rest and complete it when the float rises), simply remove the retaining clip, remove the float, flip it upside down and replace the float and retaining clip. Note that you cannot do this with the Madison M8700 horizontal mount switch that we sell.

Switches should never be inverted (the Madison M8700 horizontal mount switch is an exception and can be inverted). The threading should always be up and out of the water.

For quantities of 25 or more, we can special order the switches so that they are delivered to you normally open. Contact us for more information.

Do float switches require maintenance?

Doesn’t everything? Used properly, float switches can last for years. Just make sure the stem is clean and does not have any residue or build-up. Check your switches often (at least once a month) and clean them with a soft cloth. In necessary, remove the bottom clip and the float. Just remember not to invert the float or it will change the way the switch works.

How would I use the switch in an auto top off application in an aquarium?

See our top-off project suggested set-up page for some great advice on this application.

How much of the switch will be below the liquid level?

Liquid will rise to be level with the top of the float and then raise it about 3/16″ before opening the circuit (i.e. shutting off a pump if that is your application). At that point, about 1″ of the complete switch assembly is under water.

Can a float switch be completely submerged?

You should not submerge float switches without sealing the top. The epoxy that holds the wires in the stem is watertight, but it is not designed for long-term submersion. Our i-float tubing adapterand our M8000 tubing adapter offer basic protection.

Why do you sell the Maxijet 600 over the Maxijet 400, 900 or 1200?

No particular reason other than that it is versatile and has a head of 53″, which will work for many applications. If you follow our recommendations and use a relay (see Curing Spiking Voltage with a Relay), the relay we sell has contacts rated for 15 Amps, which will handle a fairly substantial pump.

What are your shipping procedures and charges?

See Shipping & Returns