So I have this sump pump

[bucolic_frolic]

It's old, it works well, maybe losing a little power. Has a separate float switch. Pump sits underwater - forever.

Last week I dump 5 gallons of water in the hole, on the underwater pump, and the pump shorts out. Trips GFCI's, and makes the lights go dim for circuits without GFCI, though it does pump.

Today the pump is working fine again, no longer shorts GFCI's, works with the float switch or without.

No question for you, but this is inexplicable. The pressure of throwing 5 gallons of water on it caused a temp short. Now what.

[Bluethroughu]

1. I would say maybe something created a block inside the pump but pushed through

Maybe that is why you had a short, but you could unplug, pull it up and just check the wire all the way to the pump and see if it might need a cleaning.

[bucolic_frolic]

2. Oh. So like some little piece of metal shaving or such was jostled loose inside

maybe around the brushes, but worked its way off. Interesting explanation. I will examine the wires, maybe a crack somewhere. it's
about 25 years old I think.

Thanks for the insight!!

[Bluethroughu]

3. If you have got 25 years out of it, it's definately lived up to its value!

Use a little dish soap and toothbrush to clean, rinse with warm water, and you might get another 25 years.

[taxi]

4. If circuits beyond the GFI powering the pump were affected, then the GFI may be the problem.

Had it functioned correctly the power to the pump all circuits feed by that same GFI would have been cut. A bad spot on the armature could cause an intermittent problem. A faulty 220v pump may have created a back feed.

[Kali]

7. this

[KY_EnviroGuy]

5. Did you try throwing another bucket of water in the sump to see if the problem repeats?

The trip was likely cause by electrical leakage either in the motor, foot switch or power feed cord. You could have a worn out pump shaft seal or cable seal which would not be surprising for an old unit. You might see something by pulling the unit and giving it a careful inspection.

Is it a submerged motor unit like the Zoellers?

My suggestion would be (if practical) to take it to a motor shop and get them to run an electrical leakage test on all the components when submerged in water. I have the instruments to do that and they have helped me solve some major problems. Many time, the older units can be repaired and just kept as an emergency spare.

You probably don't want an elusive electrical time bomb problem that won't repeat unit you really need it and then get a flooded basement.

KY

[bucolic_frolic]

8. That makes sense to me

The pressure of the dump of water increasing water pressure.

I have a multimeter, I found some Youtube vids on testing sump pumps. So I'll go there.

Yes it's a submersible, hardware store brand as I recall, I think made by Flotec of the era. Independent electric cord, mercury float switch easily replaced.

[Sneederbunk]

6. Preventative: Do not pour 5 gallons of water in hole.

[bucolic_frolic]

9. Cleaned it. Tightened the seal on top 1/4 turn.

Last edited Wed Dec 7, 2022, 02:27 PM - Edit history (1)

I think that might fix the problem, the nut on top is where the power cord enters and is sealed with some type of internal rubber or silicone washer. The pump is 30 years old, tag date of 1992. It's on the third float switch, which is about 10 years old.

If the pump dries out during a dry spell, I'm thinking to put some silicone caulk over the nut as well for good measure.

Thanks to all who responded.