Sump Pump Switches

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UPDATED: July 5, 2017

Sump pump switches are the main link for controlling the sump pump. The main cause for sump pumps to not operate properly is the switch. Without the switch, the pump will not turn on. There are basically three types of switches; vertical, diaphragm, and tethered. There is an electronic switch that we will get into later.

All switches have good and bad attributes that make them better or worse suited for certain installations. The switch is important, but the proper installation of the switch is more important. Sump pump switches are used to make sure that the water from a drainage system won’t overflow. Thus a sump pump is usually on to avoid flooding but if it there isfailure for that to occur, you can manually turn on the sump pump switch. If your sump pump switch is not working, it might be time for a repair.

Sump pumps can be found at Home Depot and Lowes! Replacement and maintenance can be costly but with these tips and an adjustment or two, you’ll be able to fix your switch in no time. It’s hydromatic, meaning it has functions like an automatic transmission that was originally developed for cars. They come in different shapes and sizes ranging from mini to giant. There are different kinds of pumps out there too, like a modern Flotec pump, or a Watchdog alarm pump.

The Zoeller Pump Company is another great place to purchase your sump pump. There’s also submersible Utilitech and Myers sump pumps, as well as durable Wayne pumps, you can invest in. Top suction design in Ridgid sump pumps prevents air locking for ultimate reliability. You get to be the controller to determine which sump pump is right for you. To find out what’s best for you and to learn more about sump pump switches, keep reading! This section we will discuss the do’s and don’ts about sump pump switches.

To piggyback or not?

The easiest way to tell if you have a piggyback plug is to look at your plug, is there one cord or two? If there are two cords then you have a piggyback plug. If you have only one cord you may have a vertical switch that is internally wired and permanently connected to your pump.

Sump Pump Switches

Piggyback plugs make it very easy to test your pump. Identifying the two cords is easy. The cord that only has the male plug is for the pump and the cord that has both the male and female end is the switch. To test the internal pump, unplug the pump cord from the switch cord.  Now plug the pump cord directly into the outlet. If the pump turns on the pump is operating.

Importance of the Switch

Properly installing a switch is vital to proper operation of the pump and protection of your basement. You don’t want bells and alarms going off in your head thinking “how do I do this?” The last thing we want is for you to be stuck and unsure what to do. Some switches are adjustable and some are not. It is very important that the pump is cycled properly. If a pump short cycles (runs for a short period of time often) this can put unwanted stress on the pump.

Sometimes a switch can be installed too low and the pump can dry run. All submersible pumps are designed to be under water when running. The water acts, as a cooler to make sure the pump does not get excessively hot. Though most pumps have thermal overload switches, overheating a pump is one the quickest ways to shorten its life.

Vertical Switches

Vertical switches are well suited for most installations because they are easy to install and adjust. Most, if not all vertical switches utilize a piggyback plug.  The vertical switches operation is very simple. The vertical switch consists of a float, some sort of rod, and a switch enclosed in a small housing attached to the pump body or the discharge pipe.

Vertical Switches

As the water rises in the sump basin, the float rises with the water. At a predetermined height, the float activates a switch and the pump is turned on. As the water level falls the float falls with the water and again the pump is shut off at a predetermined height. Vertical switches are great for small diameter basins. The vertical switches motion is somewhat controlled since it travels on a rod that is affixed to the pump or discharge pipe and does not vary much. The issue with most vertical switches is that they are not well suited for deep basins. This switches cycle is limited to the length of the rod.

Diaphragm Switches

Diaphragm switches work well for some installations.  Most, if not all diaphragm switches again utilize the piggyback plug. Diaphragm switches operate differently than most other types of sump switches. A diaphragm switch is triggered by pressure.  This type of switch is usually mounted very low on the pump body or on the side of the pump.

Diaphragm Switches

As the water level rises in the sump basin, the pressure exerted on the switch is increased. Once the pressure is high enough to compress the bladder contained within the switch, the switch is energized and the pump is turned on. As water is pumped out of the basin the water level falls and thus the pressure falls. Once the pressure on the bladder contained within the switch is low enough, the bladder expands again and the switch is de-energized. These types of switches are great for basins with very little room or basins that are congested. One of the problems with diaphragm switches is adjusting the trigger levels. Diaphragm switches ARE NOT adjustable making it very important to select the correct switch.

The Tethered Switch

The tethered switch is one of the most common types of switches. The switch can either be piggybacked or internally wired. The switches operation is very simple. A tethered switch usually consists of a cord attached to a float that may be round or oval in shape. Inside of the float is either a steel ball or mercury. The mercury switch is cheaper to manufacture but is becoming less desirable because of the environmental impact. The cord itself can be either attached to the pump itself or hung from the basin lid. When the switch is hung from the lid it will have a weight to connected to it so the cord can pivot. In both types of installations, the operation of the switch is the same.

Tethered Switch

As the water level rises the switch floats with the water. Once the float extends the cord out it begins to pivot. The switch continues to float and pivots straight up and the steel ball or mercury sinks to the bottom and energizes the switch. As the pump is energized the water is pumped out of the basin and the water level falls. Again as the cord is extended down and the steel or mercury sinks to the other end of the switch, de-energizing the pump.

This type of switch requires a lot more space than any of the other switches. This switch should not be installed in a narrow basin because of the likelihood that the float could get hung up on either the side of the basin or the pump. Tethered switches are adjustable but you must take care of them. The more cord that is left out the more likely the float can get hung up or tangled on something within the basin. The most common tethered installation a homeowner is going to find is the switch attached to the pump. In commercial applications, it is more common to find the switch hung from the lid.

Electronic Switches

There are many different types of electronic switches. Many of these switches are new to the market within the last five years or so. The advantage of most electronic switches is they have very few if any, moving parts. One type of electronic switch uses a probe. This probe is installed at the level you would like the pump to be energized. With this type of switch, the runtime is either preset or adjustable on the control box.

Electronic Switches

Another type of electronic switch utilizes a float or dual floats which travel within a caged housing. With this type of switch, a sensor senses the location of the float(s) and energizes or de-energizes the pump. Again the control box is installed outside of the basin. There are two main advantages to this style of switch. The first advantage is location. The control box is located outside of the basin usually on the wall. Removing the control box from the harsh environment of the basin aids in the control boxes life. The second main advantage is the lack of moving parts. The less moving parts, the less chance that something can go wrong.

Checking a Sump Pump Float Switch

As we have discussed there are many types of switches so it is important to identify which type of switch is installed on your pump. Confirm you have power at the outlet. It is important to use care when checking that there is voltage at the outlet. You can use a digital voltage multimeter to confirm power is present. If you do not own a multimeter you can use any device such as a lamp or light.

Once you have confirmed there is power present you will have to open the basin. Most sump basins are unsealed but have a cover. Some covers will be bolted down and some may be sealed. If your home has a radon mitigation system installed it is very important that the cover is installed and sealed in the same manner it was found.

Once the cover is off and located and you’ve identified the switch, a tether switch is easy to test. In order to test a tether switch simply grab hold of the float and position it so the wire side is facing down. Make sure the tether is not getting tangled with any other cords or the side of the basin. If the pump turns on the float is working but it is important to confirm the pump turns off when it is cord side up.

To test a vertical switch locate the float on the switch. Take the float and lift it straight up till the float has no more travel. If the pump turns on the switch is working but again, confirm the pump turns off when you let go of the float. Electronic switches such, as a dual float switch is similar. Locate the floats inside the switch and move one up with either a screwdriver or coat hanger.

The next test will work with any switch but is needed to test either a pressure switch or electronic sensor switch. First, identify the inlets to the sump pit. These inlets will have to be plugged with a large towel or test plug. Now that the inlets are plugged in, fill the pit with a hose or bucket. Pay attention to when the pump cycles. A pump that turns on is great but it is important to make sure the pump turns off so it does not burn up. If none of these tests cycled your pump and you have a piggyback switch you have one more option to test your pump. You can separate the male pump plug and the piggyback switch plug. Plug the pump plug directly into the outlet and hopefully, your pump turns on. This can also be used in an emergency when a basement is flooding and the switch appears to be broken. Whenever dealing with electricity be certain to take the proper precautions to make sure you are safe.

Replacing a Sump Pump Switch; The Key to a Dry Basement

The easiest way to replace a sump switch is to identify the type of switch installed and replace it with a similar type. Please note that internally wired switches are not replaceable unless returned to the manufacturer. A pedestal sump pump can be found in a basement, partially above and partially below the ground.

It is possible to replace one switch with another type of switch. Before replacing a switch make sure that all plugs for the pump are unplugged unless you want to take a shower. Sometimes it is easier to disconnect the pump from the discharge piping and remove it from the basin.

To remove the pump, locate the check valve. The check valve is normally connected with hose clamp or union halves which are attached to the check valve. The bottom clamps or union halves are the only ones you want to loosen. If you loosen the top connections all the water the check valve is holding back will be in your face.

Once the check valve is separated from the piping the pump is ready to be removed.  Take care in removing the pump that no wires are caught on anything.  After removing the pump locate the switch. Remove the switch and prepare to install the new switch. Not all switches look the same so it is important to pay attention to how the original switch was installed. Follow the directions supplied with the new switch. Install the new switch and secure the wiring so it will not interfere with the switches operation.


  1. Great information. Those tethered float types have caused me nothing but problems. My new pump came with a vertical type which works well.

  2. I have a vertical float switch. The sump fills with water to over top of the float with the float actually floating. The switch will not click to on. If I shake the outflow pipe, which shakes the pump/water, the switch will click to on, drain, and click off. Or I reach in and pull it past that “click” point to on. But the float will not get it past that “click”. I even fashioned a street hockey ball to it for extra buoyancy. It was free and clear to pull it up and did so but still didn’t pull it past that “click”. I have removed it because the way I had it fashioned was preventing it from shutting off. What can I do to get the float to get past that “click” to turn on?

  3. piggyback are not there on the setic pump we have two float I the tank. can we wire up wir. it. side pump here with out using g the plug for float with out. piggy backin . it

    1. I’m not aware of anyway to bypass a bad float/switch without using a piggyback float. I’m sure if you’re a master electrician you maybe able to rewire the switch but it seems like an awful lot of effort when you can just replace the pump.

      Sean K

  4. can we run pump floats with the plug not there some how .still have plug fo . pump.but not . to floats. like bac . in out let somehow

  5. Howdy! Quick question that’s entirely off topic. Do
    you know how to make your site mobile friendly? My website looks weird when viewing from my apple iphone.
    I’m trying to find a theme or plugin that might
    be able to correct this issue. If you have any suggestions, please share.

    Appreciate it!

    1. Quite a few of our sites use a custom Genesis theme. Although we do quite a bit of coding ourselves Genesis is inherently mobile friendly.

      Sean K

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