reefpeeper
Valuable Member
how would one test for stray voltage?
stray voltage
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Dowtish
5000 Club Member
I was talking with a rep. from hydor about some possible stray voltage, and got this in one of the many emails from him, thought it's worth sharing:
In saltwater, which is highly conductive, you get an induced electrical current produced by the magnetic shield emanating from the electric current running through the copper wires of the electrical cord. . This is not an actual voltage leak. This typically reads as a voltage of 1 to 5 volts on a digital voltmeter. You can improve the accuracy of you voltage reading by using a standard voltmeter (analog).
I used a friend's digital meter and found some stray voltage, and could unplug each piece of equipment and watch it ramp down. But you can get a analog volt meter for like $20 at Lowes.
In saltwater, which is highly conductive, you get an induced electrical current produced by the magnetic shield emanating from the electric current running through the copper wires of the electrical cord. . This is not an actual voltage leak. This typically reads as a voltage of 1 to 5 volts on a digital voltmeter. You can improve the accuracy of you voltage reading by using a standard voltmeter (analog).
I used a friend's digital meter and found some stray voltage, and could unplug each piece of equipment and watch it ramp down. But you can get a analog volt meter for like $20 at Lowes.
OP
OP
reefpeeper
Valuable Member
what voltage is too high then?
dv3
unregistered
i always though stray voltage was caused by the propeller spinning and "creating" the voltage and is different than a short circuit where your electricity is 'leaking" from a failure in the insulation of the equipment
personally i feel in most cases where people are blaming true stray voltage on their problems its probably just a coincidence and the stray voltage may just be compounding a larger problem at most
personally i feel in most cases where people are blaming true stray voltage on their problems its probably just a coincidence and the stray voltage may just be compounding a larger problem at most
andywe
Well-Known Member
I always use a ground probe in my sump which would alleviate any stray voltage. One like this:
A grounding probe does not alleviate it. It gives it a path to ground out so if you have a true voltage issue in your tank you don't get the full package through you when you touch the water. The problem still exists,, just the probe offers a pathway out of the tank. Voltage still flows through the tank. Thats why a probe in combination with a GFI outlet as the first outlet in your circuit is a must!
btkrausen
Fish Hoarder
Sorry, thats basically what I meant. I didn't mean to elude that a grounding probe would fix the problem
andywe
Well-Known Member
Sorry, thats basically what I meant. I didn't mean to elude that a grounding probe would fix the problem
I was onl;y concerned that you might think it would keep you from getting harmed if a powerhead or something went bad. I got shocked last month from a maxi 1200 that finally bit it on a gfo reactor and thank god I had GFI....so I was only heavily tingled rather than fried lol.
Monroereef
Well-Known Member
Sorry, thats basically what I meant. I didn't mean to elude that a grounding probe would fix the problem
But won't the grounding probe covert voltage into stray current?? I think current is much more of an issue than stray voltage in a tank (both for us and the live stock)...
robert
Valuable Member
A GFI circuit compares the current flowing on the hot side of the AC outlet with the current flow on the neutral side of the AC outlet. If there is even a small difference in current between the hot and neutral, the GFI will open the circuit. If you have a voltage in your tank the ground probe will send this current to the third prong on the AC outlet - not the neutral. Since this current is coming from the hot-side and is being returned on the third prong (safety ground) there will be a current difference between the hot and neutral and the GFI should trip.
If you don't have a GFI on the outlet, you won't be protected by a ground probe.
Adding a ground probe to a non-CGI circuit guarantees that any voltage in the tank also produces a current. That current may be significant yet not be enough to trip your breaker. Voltage in your tank, without a path to ground means that when you touch the water - you provide the path - that's when you feel the bite. The better your grounded (barefooted - wet carpet, etc) the bigger bite you feel.
The problem with using a multi-meter to measure voltages in the tank is just as the hydor rep stated in the post above.
"In saltwater, which is highly conductive, you get an induced electrical current produced by the magnetic shield emanating from the electric current running through the copper wires of the electrical cord. . This is not an actual voltage leak. This typically reads as a voltage of 1 to 5 volts on a digital voltmeter. You can improve the accuracy of you voltage reading by using a standard voltmeter (analog). "
If your using a digital multi-meter, it is not uncommon to read induced voltages of tens (20,30 even 40) of volts between water and ground. Everything you unplug may drop this reading a little or not change it at all. This can be confusing and doesn't indicate any problem whatsoever.
I have found the simplest most reliable method is to use a simple 100-600v AC Voltage Detector. These are those devices that have a probe tip that you place in proximity to a conductor and it will chirp and/or flash if there is an AC voltage present.
(one I use - EXTECH 40130 - $10)
Turn it on, put the probe tip against the glass/plexiglass of your tank - if it chirps/flashes you have a voltage leak. If it doesn't - you don't have a problem.
Make sure you test when everything is actually running. Chillers are notorious for causing voltages in tanks that you won't find until the chiller actually kicks on.
These AC voltage detectors are cheap ($8-$12 range). You can get them at any hardware store or Frys etc. and in my experience, they are 100% accurate at determining if you have a true voltage problem.
So much simpler than the multi-meter method.
If you don't have a GFI on the outlet, you won't be protected by a ground probe.
Adding a ground probe to a non-CGI circuit guarantees that any voltage in the tank also produces a current. That current may be significant yet not be enough to trip your breaker. Voltage in your tank, without a path to ground means that when you touch the water - you provide the path - that's when you feel the bite. The better your grounded (barefooted - wet carpet, etc) the bigger bite you feel.
The problem with using a multi-meter to measure voltages in the tank is just as the hydor rep stated in the post above.
"In saltwater, which is highly conductive, you get an induced electrical current produced by the magnetic shield emanating from the electric current running through the copper wires of the electrical cord. . This is not an actual voltage leak. This typically reads as a voltage of 1 to 5 volts on a digital voltmeter. You can improve the accuracy of you voltage reading by using a standard voltmeter (analog). "
If your using a digital multi-meter, it is not uncommon to read induced voltages of tens (20,30 even 40) of volts between water and ground. Everything you unplug may drop this reading a little or not change it at all. This can be confusing and doesn't indicate any problem whatsoever.
I have found the simplest most reliable method is to use a simple 100-600v AC Voltage Detector. These are those devices that have a probe tip that you place in proximity to a conductor and it will chirp and/or flash if there is an AC voltage present.
(one I use - EXTECH 40130 - $10)
Turn it on, put the probe tip against the glass/plexiglass of your tank - if it chirps/flashes you have a voltage leak. If it doesn't - you don't have a problem.
Make sure you test when everything is actually running. Chillers are notorious for causing voltages in tanks that you won't find until the chiller actually kicks on.
These AC voltage detectors are cheap ($8-$12 range). You can get them at any hardware store or Frys etc. and in my experience, they are 100% accurate at determining if you have a true voltage problem.
So much simpler than the multi-meter method.
Last edited:
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