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sump pump switch false alarms


More options. 
I'll look into these other switches.  The float switch is  Inside a septic tank pump station which is corosive. Even the wire connections need to be sealed or outside of the tank. This is the main reason I went with this type of switch.  Furthermor they have plenty of space to move/operate correcly if the water level reaches a critical point.  The float switch  is probalby mecanical with a magnet switch mecanism, so it is ok for a 12 volt DC relay.
As I am diging into this I will look into replacing the float switches as I am reading that they seem to fail after several year.  I don't want to end up with a defective float switch the day it need to do its job!   I noticed that there are some that are Normally closed contact float switch such as the ones sugested in this post and this one:

By having a NC  I could monitor (EOL resitance) or get a warning (alarm condition) if the cabling gets defective. 



Senior Member
Below are two links that show how two styles of mechanical float switches work.  Both use a metal ball that rocks back and forth to activate the switch.  As a result, they can be less than precise.  
Still, if you are getting false alarms, it probably means the switch is being activated in some way.  Usually, the switches fail because the seals leak.  Water inside the canister may weigh the float down, which would cause it to activate later than it should, or not at all.  Or, if the liquid is at all conductive, it might create a short between the contacts which might be the cause of your false alarm.
As I mentioned previously, think about whether it could be the pump switch that is bad.  If that float is slightly flooded, it could cause a late activation of the pump, allowing the water level to get high enough to trigger the alarm float.


Senior Member
Are one or more of these switches easy to access? I would put an ohm meter on one of those switches and manipulate it so that it goes on and off while watching the meter. A false alarm on the elk indicates that the switch is leaking or to put it another way it is not going completely open when it should be open.
I don't know what kind of switch is inside that floating ball switch but a magnetic switch doesn't suffer from the same problems that a mechanical switch does. Magnetism isn't much affected by moisture or even mechanical wear and tear.
Check out these poly switches, I think that they are all safe in septic but I would ask the manufacturer. I am not recommending this brand of switch - it is just something that I found searching the net this morning.


Active Member
What about a GRI 2600/2800 water sensor? I have used several around the house and they work great. No moving parts... They run around $20 too.
Interesting thread. I had not come across those other switches.
Usually nowhere to really mount them to, the cable and units are not designed to be submerged, which is more likely in this application. Also, terminals not designed for the corrosive environment.


Active Member
DELInstallations said:
Usually nowhere to really mount them to, the cable and units are not designed to be submerged, which is more likely in this application. Also, terminals not designed for the corrosive environment.
Del, do you mean the 26/2800? When I spoke to the rep, he mentioned that it was not a bad idea to add a glop of caulk where the wires go into the housing as sometimes they do take on a little water. I thought that was weird and not sure why they would not do that at the factory. As for the contacts, i would assume they were stainless, but honestly, i don't know and never thought to ask.
Have you used a similar product that is better built? Would love to know.
I am not submerging mine. I have located them as problem detectors (bathroom, in basement, in hot water heater pan, in floor of sump room).