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Re: 120 volt power sometimes

RG, all pumps should have a low liquid level shut-off switch, so the pump section will not run dry and destroy itself.

A float switch is the oldest type but newer ones have conductivity switches. The specs usually say "on at 2", off at 4" or so.

Have you actually tried placing the pump in a bucket with water in it?

Or, there could actually be a float switch and it's stuck in the off position or it's defective.

Good Luck from Wilsonville, Alabama
Maurice Turgeon, http://thesemi-retiredelectrician.com

Fencepost
Re: 120 volt power sometimes
JLMCDANIEL wrote:

Most motors have a small amount of ground leakage, my guess is that your submersible pump exceeds that allowed by the GFCI.

Jack

The original poster didn't describe a GFI in the circuit, so I'm guessing that's not the issue. (I haven't heard of a self-resetting GFI.)

Another possibility: the receptacle outlet at the pool is just bad. Maybe the pump plug's prongs are a little thinner than the circular saw's so it doesn't make good contact.

Or, possibly, when the pump is turned on the voltage drops below what is necessary to turn the pump (but the circular saw works OK). Connect a voltmeter to the circuit where you plug in the pump -- what is the voltage when nothing's connected, and what is the voltage when the pump is connected?

JLMCDANIEL
Re: 120 volt power sometimes
Fencepost wrote:

The original poster didn't describe a GFI in the circuit, so I'm guessing that's not the issue. (I haven't heard of a self-resetting GFI.)

You're right Fencepost, that's what happens when yo're working on 2 forums at onece.

Jack

canuk
Re: 120 volt power sometimes
The Semi-Retired Electric wrote:

RG, all pumps should have a low liquid level shut-off switch, so the pump section will not run dry and destroy itself.

A float switch is the oldest type but newer ones have conductivity switches. The specs usually say "on at 2", off at 4" or so.

Have you actually tried placing the pump in a bucket with water in it?

Or, there could actually be a float switch and it's stuck in the off position or it's defective.

Good Luck from Wilsonville, Alabama
Maurice Turgeon, http://thesemi-retiredelectrician.com

Maurice --- not all pumps have a float switch.
I have a submersable pump that will run with or without liquid -- the manufacturer doesn't want it running dry mind you. They use a thermal cutoff to shut the motor down --- liquid that is being pumped is actually used to keep the motor cool.

canuk
Re: 120 volt power sometimes
rgfisher wrote:

I installed a 120v receptacle in my pool area off a dedicated GFI breaker.

When I plug in a 2 prong drop light it turns on.

When I plug in a 3 prong submersible pump to pump off my pool cover - nothing. It is not tripping the breaker. I plug in the pump in my garage - OK.

Any ideas?

rgfisher wrote:

OK

This gets more wierd.

Following Maurice's suggestion I tried the pump at both the pool and garage receptacles, by holding the pump vertical and horizontal. No change. It obviously does not have a "float switch".

Then I thought I probably have a "load" issue. I checked the pump and it draws 12 amps. I found a circular saw that draws 12.8 amps and plugged it into the pool receptacle. Worked fine!

I'm still at a loss.

Any advice would help.

To recap ---

GFCI circuit = check ( GFCI breaker )
Circuit breaker ( GFCI ) doesn't trip = check
no float switch on pump = check ( runs in the garage )
circuit powers resistive load ( lights ) =check
circuit powers inductive load = check ( power saw )

I doubt voltage drop would be an issue since the power saw seemed to work fine -- after all the pump and saw are both inductive loads. At this point it doesn't seem to be a high leakage current at the pump since the GFCI isn't tripping.

Questions --
the saw -- is it a 2 or 3 prong cord ?
Who installed the GFCI breaker -- was it installed correctly in the panel ?
Who ran the wiring and connected the receptacle outside -- is it correctly wired ?

JLMCDANIEL
Re: 120 volt power sometimes

Canuk, the saw is probably a universal motor and the submersible not. That could make a difference. Universal motors handle low voltage much better.

Jack

canuk
Re: 120 volt power sometimes

True enough though if there were enough voltage drop to not start the PSC type pump motor ( for example ) then a noticeable speed decrease on the saw would be evident. I know from experience when running power tools off a faulty genny --- low voltage results in a very noticable performance issue -- in cases like a large saw it really doesn't want to run.

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