electrical problem with electric control box on well pump

Thread Starter


Joined Aug 20, 2011
Came out to summer home and found the control box that controls the well pump constantly clicking on and off. I called to order a Grundfos control box model SA-SPM4 and they told me to use an SA-SPM5 and I also ordered a pressure switch with a safety for pressure going under 20 psi and it would shut off and that would save the motor. Now my problem is that the pump will run for 20 seconds and then shut off and when it shuts off it blows the fuses (this is not a circuit breaker it is a regular fuse). I would like to know if it could now be that the pump itself is bad. The pump is 25 years old; however, the well is only used for lawn watering as house is hooked up to city water. The pump is a 3 wire pump with capacitor start and I was wondering if I can bypass that and jump the pump wires or there a way to test the wires coming from the pump for a short?


Joined Apr 30, 2011
There could be a non-electrical explanation, a leaking pneumatic bladder in the tank or an obstruction in the discharge line for example.


Joined Nov 30, 2010
I've seen this too. The customer installed a new well and a pump and it worked until he shut off the valve to the garden hose. Then it went into the clicking on and off thing. Having never heard of a pressure tank, he was baffled. The garden hose was providing enough elasticity to hold the pressure switch off!

I added a Tee fitting and a pressure tank and it was cured.