Stray Voltage

[skewch]

Yet another stray voltage problem

I have 2 6100's, and the 7095 controller. Tonight while working on the sump, I realized I was getting shocked.

I pulled *everything* electrical out of the sump (sump is located in another room), still got shocked. Both Tunze streams were still running in the tank in the other room.

Unplugged the 6100's, no longer got shocked. I figured it might be the power bar they were plugged into, so I plugged them into another outlet on a different circuit. Got shocked.

Now I was stumped. I had everything electrical out of the sump (probes, pumps, heater, etc.), and the only thing in the tank was the 6100's. I plugged one 6100 in, no shock. I plugged the other one in, shock. I unplugged the first one, still got shocked. Unplugged the second one, plugged the first back in, no shock.

I pulled the pump that seemed to be doing the shocking out, and put it in a bucket with salt water as per previous threads about this. No shock.

I put the pump in question directly in the sump, plugged it in a totally different circuit again, got shocked.

I am stumped. I understand the rationale behind the grounding on the pump which may complete the circuit and cause the shock from some other device which is leaking current, but why do I only see it when the one pump is on, and not the other? Is it possible the pump I think is good is actually the one with the problem, and the one that seems problematic is good?

Both are fairly new, less than a month old. I need help figuring this out

 

[rvitko]

The electronic pumps have no ground and 19V would be really below the threshhold of what you could feel at the amperage used (.3). I don't think this is possible. If the pump was shorted it could not run, an electronic pump has electronics inside the pump that if breached would cause a failure.

 

[skewch]

Thanks for the quick reply Roger.

I didn't realize the electronic pumps weren't grounded (well in retrospect, now I realize that the plugs don't have the ground plug itself, doh).

Now I am totally lost. Would it be worth it to try the driver from the pump I think is good, on the pump that I think is bad?

 

[rvitko]

I would be fairly certain it has to be something else. As I said, inside the pump is a small circuit board and once shorted- bzzt, dead pump. It cannot run without that. 19V at .3A is barely detectible to human touch. I just can't imagine a possible cause. I would run all tests in a plastic bucket. Watt meters have become very cheap and you could also check the watt draw, if it is much higher than about 45W it would point to a problem.

 

[skewch]

Okay, I went back to the salt water bucket (it's a 18g garbage can). I realized I had added fresh water to this bucket the other day, so I tested the salinity, and it was only 1.015. I added salt and brought it up to 1.025 to match what's running in the tank.

I pulled out the mixing pump and heater, and threw the 6100 in. Then subsequently got shocked I tried it on a different circuit, same shock. I must have missed it the first time around because the salinity was lower and it wasn't as noticeable. It feels just like it did in the tank/sump now.

Going to go see if I can figure out how to work the voltmeter now

 

[rvitko]

A wattmeter is really what you want, the appliance plugs into it and it tells you the watt draw which increases if a problem is present.

 

[skewch]

Okay, I'll grab one at Home Depot tomorrow.

This is driving me insane, now it appears to be working fine, can't get it to shock me for the life of me Even works in the sump now.

Thanks for your help, I'll post back when I've tried the wattmeter.

 

[rvitko]

Radio shack will have them most likely, their is one called Kill O Watt that costs about $40.

 

[Timbo]

If it's a 45 watt pump you're correct that its pulling .3A from the wall (120VAC) but since the motor runs at 19v, the electronic driver is sending ~2A to the motor in the aquarium.

 

[FinsReef]

Save yourself and use your voltmeter to measure how much current you have going thru your tank. Ground the black, and stick the red in the water. That way you can see if you have stray voltage without all the pain and tingling.

 

[rvitko]

You are correct Timbo, sorry, I was getting tired.

 

[bruffin]

You might want to just see about getting an aquarium grounding probe, which sucks up the stray voltage. They cost between $10 -$18 and you get them from just about any aquarium store online . . .

 

[skewch]

Thanks guys. I do have a grounding probe on order, should be here tomorrow (for unrelated reasons, mainly the pH probe with my Aquatronica). I will try the voltmeter again, thanks for the tip Finsreef

I am really stumped as to why 1 pump does it, and the other doesn't.