Stray Voltage - Ow my fingers hurt

[mcphock]

A bit of information first:

When I geared up to put my tank in a few years back, I had an electrician come in and install a GCFI outlet in the wall. All my (minimal) gear is powered through that outlet. I haven't not 'tested' that outlet (or any GCFI for that matter) since I've had it in place.

I have only 6 electrical devices that contact the water:
2x MP40
1x Mag 7
1x Mag 18 (i know, i know... way too much)
1x MJ 400 (ATO pump)
1x Ph/Temp probe for Reef Keeper Lite


A week or so back, I felt a sting when I put my finger in the water. Sometimes I bite my cuticles, and salt obviously stings in tiny cuts, so I convinced myself that was the problem. I wasn't 100% sold on that though. When I tried again a few hours later, I felt nothing.

Feeding time for the last week was fine.

Today, I spent 2 hours changing the water, fragging corals and redoing the aquascape. About 90 minutes in, I was definitely getting jabbed with needles when I put my fingers in the tank. Not good. Livestock seems to be acting fine, but this is clearly a dangerous situation. I tried unplugging everything, then plugging pumps back in one at a time. I wasn't able to identify the culprit. I suspect something is leaking voltage into the water, but it may not be persistent.

I'm in over my head here. Any advice on how to troubleshoot and resolve this without continuing to stick my hands in the water? If I had to put money on the problem, I'd guess the 5 year old Mag 18.

 

[ringo®]

Have a multimeter? Most the time, pumps are the culprit.

 

[ghbrewer]

No heater?

 

[ghbrewer]

I have had the same problem in the past, both times it was a heater.

 

[rdnelson]

Although you don't list it my guess would have been a heater as Grant said.

 

[picoreefguy]

the MP40's dont have any electrical contact with the water so you can rule them out, the mj400 is kept in your ato reservoir so voltage cant get in the tank so you can rule it out. and the ph and temp probes are very low powered so you wouldnt be able to feel it if they were leaking voltage. so my bet would be a heater or one of the mags

 

[dball711]

When I noticed this in one of my tanks I unplugged everything and plugged each electrical item one at a time till i found it...yup he heater.

 

[joseayes]

dball711;982261 wrote: When I noticed this in one of my tanks I unplugged everything and plugged each electrical item one at a time till i found it...yup he heater.

Wondering what brand heater? It helps for reference

 

[mcphock]

Nope - no heater plugged in. Not in the summer.

I don't recall wearing shoes either.... its a pretty safe bet. I don't typically in the house.

 

[mcphock]

A few more things to note:

1) I was even getting the needles touching wet frags resting on my euro-bracing.
2) Isn't this one of the scenarios a GCFI is designed to prevent?

 

[picoreefguy]

McPhock;982267 wrote: A few more things to note:

1) I was even getting the needles touching wet frags resting on my euro-bracing.
2) Isn't this one of the scenarios a GCFI is designed to prevent?

1 thats strange unless theres a path of water leading from the frag to the water in the tank.
2 im not an electrical expert but i think it takes a short circuit to trip a gfic and im thinking what you have is just a tiny bit of wire exposed to the water which would allow stray voltage into the tank and into the ground through you but wouldnt cause a short as both wires probably arent exposed.

Edit: please dont quote me on #2. i know a LITTLE about the workings of electricity but im not a professional or expert.

 

[rdnelson]

McPhock;982267 wrote: A few more things to note:

1) I was even getting the needles touching wet frags resting on my euro-bracing.
2) Isn't this one of the scenarios a GCFI is designed to prevent?

A GFI senses an unusual flow of current. On 120v the flow on the hot shod equal the flow on the neutral. If there is a difference of 5 milliamperes or more it should trip. Having said that, cheap GFI receptacles fail often. The test button give a good indication but not always accurate.

But to be truthful I suspect it is not stray voltage. I think that gets blamed way more than is actually the case. Moving salt water under induction light acts as an electrolyte in my opinion. In other words, your tank is a big battery. What type of lights do you run? Has it ever happened when the lights were off?

 

[rdnelson]

Picoreefguy;982273 wrote:
2 im not an electrical expert but i think it takes a short circuit to trip a gfic and im thinking what you have is just a tiny bit of wire exposed to the water which would allow stray voltage into the tank and into the ground through you but wouldnt cause a short as both wires probably arent exposed.

Edit: please dont quote me on #2. i know a LITTLE about the workings of electricity but im not a professional or expert.

Not at all. A circuit breaker or fuse provides protection from over current as well as short circuits (a massive over current in a very short time frame). A GFI is designed to provide quick personal protection by sensing an imbalanced current flow.

 

[jennm]

I've seen stray voltage from just about any electrical aquarium device, even lights that did not come in contact with the water.

A multimeter will confirm it.

Jenn

 

[mcphock]

rdnelson99;982278 wrote: A GFI senses an unusual flow of current. On 120v the flow on the hot shod equal the flow on the neutral. If there is a difference of 5 milliamperes or more it should trip. Having said that, cheap GFI receptacles fail often. The test button give a good indication but not always accurate.

But to be truthful I suspect it is not stray voltage. I think that gets blamed way more than is actually the case. Moving salt water under induction light acts as an electrolyte in my opinion. In other words, your tank is a big battery. What type of lights do you run? Has it ever happened when the lights were off?

I've got 4 AI Sol Blue that I've had for coming up on 3.5 years. It's never happened while the lights were off that I recall.

 

[mcphock]

Is there a preferable kind of multimeter to get? As I mentioned before, electrical stuff is complete foreign to me.

 

[jennm]

I just used a cheap (or free with coupon) one from Harbor Freight.

 

[rdnelson]

McPhock;982288 wrote: Is there a preferable kind of multimeter to get? As I mentioned before, electrical stuff is complete foreign to me.

I can pretty much guaranty that no matter the quality of the meter or what tank you test you will get a reading.

 

[dball711]

joseayes;982264 wrote: Wondering what brand heater? It helps for reference

It was a Stealth heater.

 

[mcphock]

barry_keith;982316 wrote: I can bring mine over if you want steven.

every tank I've ever had has had some SV. I just assumed its normal with electronics and saltwater. Shoes help ��

Thanks for the offer, Barry. Since it appears to be an intermittent problem, I went to Home Depot and got my own.

I came home, fired it up, set it to 200 VAC, and got .1. Hmmm. Stuck my hand in the water and no shock. I'll guess i'll just have to periodically check...!