Is a certain small amount of stray voltage normal?
- Thread starter tgunn
- Start date
dougwilliams
New member
Unless something is electrically tied to ground (ie the water in your tank) its not unusual for it to "float" up and down in relation to earth ground. 1V is not unusual at all. Were you measuring AC or DC? And how accurate is the meter you used (and if its electronic, does it have fresh batteries)?
Most likely the difference is from submerged pumps. 1V isnt enough voltage to overcome the human dielectric potential, so either way it shouldnt be a safety factor unless the voltage differential climbs up higher. You can mitigate that by using a titanium grounding probe in the water and tying that to earth ground. That should help - but in theory if you measure again at the farthest point in the water to earth ground you could still see some amount of potential- mostly caused by the fact that you could develop a voltage across the salt water itself. At that poiint I wouldnt be concerned.
Most likely the difference is from submerged pumps. 1V isnt enough voltage to overcome the human dielectric potential, so either way it shouldnt be a safety factor unless the voltage differential climbs up higher. You can mitigate that by using a titanium grounding probe in the water and tying that to earth ground. That should help - but in theory if you measure again at the farthest point in the water to earth ground you could still see some amount of potential- mostly caused by the fact that you could develop a voltage across the salt water itself. At that poiint I wouldnt be concerned.
tgunn
Active member
I'm using a small analog voltmeter... My lowest AC reading is 10v and it read nothing.... I switched to 2v DC (lowest DC reading) and got the 1V reading. I'm not sure how accurate the meter is.
I have 2 inline gen-x style pumps and a large sequence pump on my closed loop. Otherwise the only electrical things in the water are my Won Bros heaters and temp probes; I should see if unplugging those eliminates the stray voltage.
The main reason I asked is that I was curious if the stray voltage was normal or if it was something that could be interacting with my ORP probe (which doesn't seem to work properly).
Thanks,
Tyler
dougwilliams
New member
If the ORP probe is battery powered it shouldnt make a difference - your tank is floating and the probe is also.
dougwilliams
New member
If the 12V DC adapter has two prongs, the its floating, if it has 3 then its grounded.
boxfishpooalot
Active member
Saltwater gives off voltage from the molecules that move in the water. Not sure whats a normal number though.
Sombody on rc said that, possibly Greenbeen or RHf.(Biologist or chemist)
So yes some is normal, but i imagine the numbers are very small. And not enough to meausre on a volt meter. Or maybee so.
Sombody on rc said that, possibly Greenbeen or RHf.(Biologist or chemist)
So yes some is normal, but i imagine the numbers are very small. And not enough to meausre on a volt meter. Or maybee so.
boxfishpooalot
Active member
<a href=showthread.php?s=&postid=7205669#post7205669 target=_blank>Originally posted</a> by tgunn
I'm using a small analog voltmeter... My lowest AC reading is 10v and it read nothing.... I switched to 2v DC (lowest DC reading) and got the 1V reading. I'm not sure how accurate the meter is.
I have 2 inline gen-x style pumps and a large sequence pump on my closed loop. Otherwise the only electrical things in the water are my Won Bros heaters and temp probes; I should see if unplugging those eliminates the stray voltage.
The main reason I asked is that I was curious if the stray voltage was normal or if it was something that could be interacting with my ORP probe (which doesn't seem to work properly).
Thanks,
Tyler
Also my Won bros heater was leaking from the sensor. You may want to check that.
tgunn
Active member
boxfish,
I figured some small amount of voltage would be expected; just wasn't sure..
I think my Won Bros heaters do leak to some small extent; when I unplugged them both the stray current went from +1v to -1v. Or it could be 1/4v - 1/2v; I am not sure if I'm reading the scale on my voltmeter properly. Time to go digital I guess. :lol: It's not a large amount though and I never get any tingling sensations...
I will have to keep an eye on them; I certainly don't want to have large stray voltages.
Thanks,
Tyler
I figured some small amount of voltage would be expected; just wasn't sure..
I think my Won Bros heaters do leak to some small extent; when I unplugged them both the stray current went from +1v to -1v. Or it could be 1/4v - 1/2v; I am not sure if I'm reading the scale on my voltmeter properly. Time to go digital I guess. :lol: It's not a large amount though and I never get any tingling sensations...
I will have to keep an eye on them; I certainly don't want to have large stray voltages.
Thanks,
Tyler
dougwilliams
New member
I'm a bit rusty on my chem - but I'm not sure if thats possible, and if anything I could only see that occuring on the molecular level. If I think of common salt - I dont think it has any net electrical charge - so it would have to be broken down into NA+ and Cl- ; at that point you'd have a net charge on the order of one electron volt per ion. If my memory is correct that's only 1x10^-19 Volts. Not at all meaurable by any common meter someone would have around. And even then, because you had a single positive and a single negative ion, the net charge is now 0. So even if that tank was saturated the net charge would still be 0.
Electrical issues in salt water are very complicated. I personally would pay no attention to a 1V measured DC potential between a reef tank and a ground.
I do ground my reef system, particularly to enhance the ability for GFCI outlets to trip if there is a voltage leak from a device into the tank.
If the tank is not grounded, one cannot expect that it will necessarily show a zero potential between itself and a ground. Sort of like rubbing a nonconductive piece of plastic in your hair and getting a static charge: there is nowhere for the voltage/electrons to go, so it sits there.
Also, there are many situations where voltages and currents can be induced in conductive media like seawater. Not only from electrically live things like ballasts, lights, wires, etc, but even from dissimilar metals. For example, take your volt meter with two different metals on the ends of the leads and stick them into seawater in a glass. You'll see a voltage between them. In a sense it is a battery driven by the different potentials for ozxidation and reduction by the metals involved.
I do ground my reef system, particularly to enhance the ability for GFCI outlets to trip if there is a voltage leak from a device into the tank.
If the tank is not grounded, one cannot expect that it will necessarily show a zero potential between itself and a ground. Sort of like rubbing a nonconductive piece of plastic in your hair and getting a static charge: there is nowhere for the voltage/electrons to go, so it sits there.
Also, there are many situations where voltages and currents can be induced in conductive media like seawater. Not only from electrically live things like ballasts, lights, wires, etc, but even from dissimilar metals. For example, take your volt meter with two different metals on the ends of the leads and stick them into seawater in a glass. You'll see a voltage between them. In a sense it is a battery driven by the different potentials for ozxidation and reduction by the metals involved.
tgunn
Active member
Hi Randy,
Thanks for the great explanation. What you've said makes perfect sense....
The ground probe to help GFCIs detect stray voltage from leaky equipment is a good idea. Do you find you get any nuisance trips from that?
I discovered yesterday that my GFCIs do indeed work when I accidentally dropped the T5s over my sump into the sump. Ooops! Am I ever glad I went for the GFCIs or that could've been bad!
Thanks again,
Tyler
Thanks for the great explanation. What you've said makes perfect sense....
The ground probe to help GFCIs detect stray voltage from leaky equipment is a good idea. Do you find you get any nuisance trips from that?
I discovered yesterday that my GFCIs do indeed work when I accidentally dropped the T5s over my sump into the sump. Ooops! Am I ever glad I went for the GFCIs or that could've been bad!
Thanks again,
Tyler
dougwilliams
New member
I wouldnt call any trip of a GFCI or circuit breaker/fuse a "nuisance trip". If you are able to trip any safety device sold in this country (USA - with our national electric code and UL type ratings and all of that)- then you have a real problem, not a nuisance. If something trips you should be looking for a real problem, not findsing a work around to something you feel is a nuisance.
Also - a GFCI is by no means the be all and end all to electric safety. It is one safety device that protects against only one type of system fault. A GFCI can only interrupt the circuit if it detects an imbalance between the "hot" and "neutral" lines in your circuit. An easy example where a GFCI is useless is if you grab those wires with each hand. All of the current passes through your body and back down either Hot or Neutral. There is no imbalance ever in the current and the GFCI will not trip, but you could easily be killed. A circuit breaker is there to limit the total amount of current flowing in the branch, but they dont break until 20A or so- and you could die with a only a few milli-amps.
The ground probe to help GFCIs detect stray voltage from leaky equipment is a good idea. Do you find you get any nuisance trips from that?
I put my electrical devices on as many different GFCI's as possible, so that if something trips, not everything does. I use about 10. I had a fair problem with that years ago, but not so much now. Maybe the devices that I presently use are less "leaky".
I put my electrical devices on as many different GFCI's as possible, so that if something trips, not everything does. I use about 10. I had a fair problem with that years ago, but not so much now. Maybe the devices that I presently use are less "leaky".
tgunn
Active member
Granted; however my experience with GFCI is that some can be subject to true nuisance tripping.
There were GFCIs on the outdoor car plugs in the last house I lived in; when the timer turned on to heat up the engine block the GFCIs would trip if it was extremely cold outside; a true nuisance trip... In fact, the electrical code in my area changed so that GFCIs are not required in this application any more...
Yes, I agree that a GFCI alone isn't a guarantee of electrical safety. We're dealing with saltwater and electricity here; two things that don't mix well.
Thanks,
Tyler
tgunn
Active member
Wow, 10 GFCIs; but I guess it's best to limit a trip to a single device if at all possible.
I've only got two separating my "life critical" systems into two groups, either which can keep the main tank alive on it's own.
I haven't got any leaky equipment so far since most everything is external, but it was just a curiosity none the less.
Tyler
stray voltage
stray voltage
Hi everyone, I do not want to hijack this tread but I was reading and I realize that I have a little problem in my 80 gallon tank.
I do not measure the voltage but if I touch the water whith my hands and I do not have shoes I feel a strong sensation of electrical, so strong that it is dificult to hold your fingers in the water.
So this is a problem no?
I will make a measurement of the ac voltage. i do not have a ground proube. there are dificult to find here in argentina.
Do you know a good DIY ground probe?
thanks
diego
stray voltage
Hi everyone, I do not want to hijack this tread but I was reading and I realize that I have a little problem in my 80 gallon tank.
I do not measure the voltage but if I touch the water whith my hands and I do not have shoes I feel a strong sensation of electrical, so strong that it is dificult to hold your fingers in the water.
So this is a problem no?
I will make a measurement of the ac voltage. i do not have a ground proube. there are dificult to find here in argentina.
Do you know a good DIY ground probe?
thanks
diego
tgunn
Active member
Re: stray voltage
Re: stray voltage
Something is definitely causing a power leak if you can feel it like that. I stick my entire arm in my tank often with zero sensation from it.
If you measure a voltage, start unplugging things until you narrow down the problem. It's probably a powerhead, heater or submersible pump.
A ground probe is just a patch for the real problem; nothing should be leaking significant amounts of juice into your tank that you can feel it.
Tyler
Re: stray voltage
Something is definitely causing a power leak if you can feel it like that. I stick my entire arm in my tank often with zero sensation from it.
If you measure a voltage, start unplugging things until you narrow down the problem. It's probably a powerhead, heater or submersible pump.
A ground probe is just a patch for the real problem; nothing should be leaking significant amounts of juice into your tank that you can feel it.
Tyler
CW from the OC
New member
I can feel a bit of electricity in mine, but only where I happen to have a cut on a finger, like a hang nail or something like that. If this something to be concened with?
I have a GFCI and a ground probe on the tank.
I have a GFCI and a ground probe on the tank.
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