Voltage meter
- Thread starter prime311
- Start date
scsinet
Active Member
You can't check a tank for stray voltage with a multimeter. It'll pick up eddy currents and give false readings.
The best thing to do is make sure all of your tank's equipment is connected through a GFI and employ a grounding probe. If you do these two things together, the GFI will trip if you have stray voltage. If the GFI does not trip, you are fine, and protected.
The best thing to do is make sure all of your tank's equipment is connected through a GFI and employ a grounding probe. If you do these two things together, the GFI will trip if you have stray voltage. If the GFI does not trip, you are fine, and protected.
reefraff
Active Member
Originally Posted by SCSInet
http:///forum/post/3004374
You can't check a tank for stray voltage with a multimeter. It'll pick up eddy currents and give false readings.
The best thing to do is make sure all of your tank's equipment is connected through a GFI and employ a grounding probe. If you do these two things together, the GFI will trip if you have stray voltage. If the GFI does not trip, you are fine, and protected.
I must be living right. I've IDed voltage leaks in a couple tanks with my meters. Could be that I have a high end Beckman but my 100 dollar sears unit did too.
http:///forum/post/3004374
You can't check a tank for stray voltage with a multimeter. It'll pick up eddy currents and give false readings.
The best thing to do is make sure all of your tank's equipment is connected through a GFI and employ a grounding probe. If you do these two things together, the GFI will trip if you have stray voltage. If the GFI does not trip, you are fine, and protected.
I must be living right. I've IDed voltage leaks in a couple tanks with my meters. Could be that I have a high end Beckman but my 100 dollar sears unit did too.
scsinet
Active Member
Originally Posted by reefraff
http:///forum/post/3004769
I must be living right. I've IDed voltage leaks in a couple tanks with my meters. Could be that I have a high end Beckman but my 100 dollar sears unit did too.
Perhaps I should clarify...
If you do have a voltage leak, the meter will definitely pick it up.
But if you read something when you use a meter, it doesn't necessarily mean you have one either.
The high input impedence on digital meters (and many analog as well) means that they are sensitive to the harmless eddy currents that are very frequently found in saltwater systems, caused by the normal operation of equipment near and in the tank.
Many aquarists stick a meter in the tank, read a voltage, and conclude that it must be stray voltage. They stick a grounding probe in the tank, the problem goes away, and they believed the identified and solved a dangerous situation, when in fact all they did was dissipate harmless eddy currents.
A GFI, on the other hand, will only trip if enough current is present to cause a problem. Eddy currents usually won't trip them, but real electrical faults will. Of course the other method to tell is to touch something grounded and stick your hand in the water... but that certainly isn't a way I'd recommend...
So my point is that the meter test provides false readings so often that there really isn't any point to testing it. Just get a GFI and grounding probe, test the GFI periodically, and rest easy.
http:///forum/post/3004769
I must be living right. I've IDed voltage leaks in a couple tanks with my meters. Could be that I have a high end Beckman but my 100 dollar sears unit did too.
Perhaps I should clarify...
If you do have a voltage leak, the meter will definitely pick it up.
But if you read something when you use a meter, it doesn't necessarily mean you have one either.
The high input impedence on digital meters (and many analog as well) means that they are sensitive to the harmless eddy currents that are very frequently found in saltwater systems, caused by the normal operation of equipment near and in the tank.
Many aquarists stick a meter in the tank, read a voltage, and conclude that it must be stray voltage. They stick a grounding probe in the tank, the problem goes away, and they believed the identified and solved a dangerous situation, when in fact all they did was dissipate harmless eddy currents.
A GFI, on the other hand, will only trip if enough current is present to cause a problem. Eddy currents usually won't trip them, but real electrical faults will. Of course the other method to tell is to touch something grounded and stick your hand in the water... but that certainly isn't a way I'd recommend...
So my point is that the meter test provides false readings so often that there really isn't any point to testing it. Just get a GFI and grounding probe, test the GFI periodically, and rest easy.