Giving up on GFCI protection for hydroponic pumps

I have finally given up trying to use GFCI protection when I move move my nutrient (salt) solutions around with pumps. I was just tripping the GFCI
too often. I decided to ground the pumps and use outlets that were not GFCI protected. That seems to work well. I would feel more comfortable with GFCI protection.
I measured the leakage between the pump motor winding and ground with a DVM. It was about 80k. Tripping at 5mA would require a leakage equivalent to a 24k resistor. I think that the discrepancy arises because the leakage resistance is nonlinear and affected by the moisture-conductor contact.
Is it too much to expect of low cost submersible pumps to have less leakage than I measured? How much water can leak in?
Bill -- Support the troops. Impeach Bush. Oh, I forgot about Cheney.
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Salmon Egg wrote:

My guess is that the 80K reading means the thing is defective. I run 3 small pumps in a backyard decorative pond. Haven't tripped the GFCI in over 7 years of operation.
Ed
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Yep!
The OP likely isn't being careful about water leaks. He might even be exposing the GFCI modules to some of the salt aerosols.
If he cleans the pump motors and wiring (and uses some WD-40, he might have better luck. Trip indicating GFCIs would minimize "down time."
GFCIs do a very good job of detecting current leakage and that appears to be what he has.
Since he can't control the leakage I hope he grounds everything with multiple paths (in a wet environment, wires and ground connects can have problems.)
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On 7/2/07 4:51 PM, in article ZtmdnWJKR4MVXxTbnZ2dnUVZ snipped-for-privacy@nni.com,

<snip>
I do not know how to clean up water that has oozed into the innards of a submersible pump. I measure the resistance between a line pin and the grounding pin.
Bill
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Iraq: About three Virginia Techs a month


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wrote:

If possible, it would be best to strip the unit and treat the windings, as mentioned (assuming it is economically viable). Which would require flushing the windings with fresh water and then drying and perhaps treating them with one of the commercial products made for the purpose. First thing though would be to analyse and correct the reason for the water ingress, otherwise you would be wasting time. I dont know what size pump you use but perhaps a change to a low voltage unit with approved isolation tranny might be a solution to your problems. All in all it might be more economical to just go that way ?
--
Cheers .......... Rheilly P



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On 7/3/07 2:28 AM, in article 468a16b6$0$12847$ snipped-for-privacy@per-qv1-newsreader-01.iinet.net.au, "Rheilly

These are small pumps. It really is not feasible to disassemble them. I do not know how they are sealed. I certainly don't know how I would go about sealing them during reassembly. I would not be surprised if they use deformable gaskets.
Bill
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Perhaps you might want to buy "in bulk" the variety of pump that so far has caused the least trips.
Once you have some spares or a reliable type of pump, use the "no prisoners" rule. Pumps that "trip" should be taken out of service ASAP and replaced with new/renewed pumps.. Ditto for GFCIs. Units that seem to trip too often might be replaced or at least given a shot of WD-40.
When you have a "zillion" small pumps leaking water here and there you have accidents waiting to happen. At the minimum you should establish "housekeeping" routines included washing down (with the power OFF) hoses, pumps, and even wires with FRESH water.
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On 7/3/07 6:35 PM, in article lOGdndarGd6_MxbbnZ2dnUVZ snipped-for-privacy@nni.com,

These are cheap pumps starting at about $20. My hydroponics is a hobby operation. In a commercial operation it would be economic to use large high quality pumps and isolation transformers. At $20 a pump and up, a stable of spare pumps just is not feasible.
Bill -- Support the troops. Impeach Bush. Oh, I forgot about Cheney.
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80k sounds low to me too. As far as the GFCI tripping, don't forget there is capacitance to ground and that adds to the total leakage current. GFCI doesn't care about phase angle of current, just total current.
daestrom
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Salmon Egg wrote:

Another possibility is to put them on an AFCI circuit. That includes 30mA ground fault detection.
-- bud--
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On 7/3/07 9:58 AM, in article 6d957$468a7fa2$4213eac0$ snipped-for-privacy@DIALUPUSA.NET,

That might be the way to go.
Bill -- Support the troops. Impeach Bush. Oh, I forgot about Cheney.
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