Electric current/voltage in Sump's water?

MuddyWaters · #1 05-10-2011, 05:30 PM

Is it normal to have a small amount of stray current / voltage in the Sump's water (where all the electrical equipment goes)? I've been researching and can't get a definitive idea if this is normal or not. Testing with a voltmeter shows approx 1 to 1.2 volts of current in the sump water (tank is zero thankfully); sump contains 1 Eheim retrun pump, 2 heaters, 1 SWC Protein skimmer. I've read about grounding probes etc. as well as the fact that they do not solve the problem, just ground out the electricity. In all cases it is suggested to find the 'bad' piece of equipment and replace; but in my case nothing appear 'bad', just each piece seems to add .2 to .4 volts to the final total, so it appears to be trace leakage from each.

I don't want to just add a grounding probe without understanding the cause or if this is normal. Do I really need a ground with this small amout? Any thoughts, conversations, suggestions would be appreciated.

sphelps · #2 05-10-2011, 05:35 PM

Small amount of voltage is perfectly normal, you'll never get zero, if you do you need a better voltmeter. I personally wouldn't use a ground probe. A GFI is a good idea, I use them on everything except the return pump.

mike31154 · #3 05-10-2011, 08:59 PM

If all you're measuring is 1 to 1.2 volts, you're doing pretty good. I reckon most people have a little more than that. And to clarify, volts & current are two different animals, you don't want to confuse them. With voltage that low, even if you add a grounding probe (which will cause electrical current to flow), the amount of electrical current will be harmless to a healthy human. A GFCI is still pretty much a must for safety reasons though.

Even with no equipment physically in the water, it is still possible to have voltage induced into the water, by fluorescent lights hanging over the tank or sump for example. The electromagnetic field produced by fluorescents and their ballasts will do this.

MuddyWaters · #4 05-10-2011, 10:21 PM

Thanks to both SPHELPS and Mike for the quick replies, glad that this is kinda on the 'normal' side of things. Already have GFCI and don't particularily want (and now probably won't) have a grounding probe. Never noticed the stray voltage before, but was just paying closer attention this time as just was replacing sump with a bigger one (10 gal to 33 gal). Thanks again for the help.

Leon71 · #5 05-11-2011, 01:49 PM

How are you measuring this stray voltage? And what is a bad amount to have?

mike31154 · #6 05-11-2011, 03:12 PM

Most people use a digital multimeter with the measurement scale set to AC Volts. One lead in the water, the other into an appropriate ground, commonly the grounding prong in an electrical receptacle.

As for what amount is considered bad, that's a bit of a tricky one to answer, but I'd start investigating the electrical components I have submerged in the water if you start seeing anything above the range of 20 to 30 VAC. As I mentioned in my earlier post, certain fluorescent lighting fixtures may induce a fair amount of voltage into the water, especially if they're close to the surface. That goes for MH lights as well depending on type of ballast and where it is located. Also worth mentioning that it's a good idea to ground individual reflectors on your T5HOs if that's feasible.

Here's some further reading which may clarify or be of use:

http://angel-strike.com/aquarium/GFI...alDetails.html

http://angel-strike.com/aquarium/GroundingProbes.html

DiverDude · #7 05-11-2011, 08:12 PM

I'd unplug each electrical device in the sump one by one until the voltage disappears.

Then replace the last thing you unplugged.

blacknife · #8 05-12-2011, 01:45 AM

I had a cable fault on one of my powerheads and was getting 120v in the tank, good thing the floor was dry when i found that. I want a ground probe but have not put one in yet.. that was not tripping the gfci either, although it probably would have with a probe.

after i fixed that 20-25v was what was left from all powerheads running.

most was coming from my internal powerheads , the rest from a heater i no longer use.

do the DC tunze pumps induce any voltage into the tank? or do only the externals<vortech> get that claim?

DOMINATOR · #9 05-12-2011, 03:40 AM

I took a "poke" three times tonight and I'm an electrician...faulty powerhead, faulty heater and faulty pump....if you stick your hand in the water and you get shocked, or feel a buzzzz, unplug things until it stops....yes, with a volt tic, you will pick up current but nothing to panic about......if it shocks you, it's shocking your investment(loved ones!$)

outacontrol · #10 05-12-2011, 05:20 AM

Quote:

Originally Posted by DOMINATOR

I took a "poke" three times tonight and I'm an electrician...faulty powerhead, faulty heater and faulty pump....if you stick your hand in the water and you get shocked, or feel a buzzzz, unplug things until it stops....yes, with a volt tic, you will pick up current but nothing to panic about......if it shocks you, it's shocking your investment(loved ones!$)

Just few friendly questions; 1. where did you get the "volt tic" that can pick up current? 2. What grounded potential is your "investment(loved ones)" in contact with that would cause them to get a shock? 3. Can I have your faulty powerhead, heater and pump please? I can arrange pickup with a friend.