Help using voltmeter to find stray voltage.

[BeanAnimal]

Do me a favor take a old power head nick a wire and place it in either a glass aquarium or a bucket of water. Then plug it into a GFCI receptacle. Now you and I know there is current in the water,

No there is no "current" in the water, only potential, as the current has no path to lower potential.

but because the aquarium and bucket are insulated there is no place for the unbalanced load to go. Now you have a choice, you can drop a grounding probe into the water and watch the GFCI trip or can do the dumb thing and stick your finger in and get the shock of your life, hopefully you will use option #1(PLEASE DO NOT ATTEMPT OPTION #2).

NO... The GFCI will trip when you stick your finger in the tank. The GFCI does not give a flying hoot where the current goes, it just knows it went somewhere other than the NEUTRAL and therefor it trips.

Also the "load" is not "unbalanced" in any context until the current is allowed to travel to lower potential other than the NEUTRAL it is intended to return on.

 

[alton]

No there is no "current" in the water, only potential, as the current has no path to lower potential.

NO... The GFCI will trip when you stick your finger in the tank. The GFCI does not give a flying hoot where the current goes, it just knows it went somewhere other than the NEUTRAL and therefor it trips.

Also the "load" is not "unbalanced" in any context until the current is allowed to travel to lower potential other than the NEUTRAL it is intended to return on.

No GFCI's will not trip until it reaches 4 to 6 MA. I do not know about you but I do not like getting shocked.:spin1:

The following is from a chart that I came across

1 ma (.001 amps) – Perception level and slight tingle
5 ma (.005 amps) – Shock Felt but you should be able to let go
6-30 ma (.005-.03 amps) – Pain Full Shock
50-150 ma (.05-.150 amps) – Death is Possible
1000 ma (1 amp) – Death is likely
Ma = Milli-Amps

 

[BeanAnimal]

No GFCI's will not trip until it reaches 4 to 6 MA. I do not know about you but I do not like getting shocked.:spin1:

I never said they would trip at a lower threshold. Thet are designed to trip at a safe threshold. The pain perception of a shock is not only a function of the current, but also the duration. A GFCI should trip in about 1/40th of a second at 5mA. That is maybe 2 to 3 cycles at most, something you are not likely going to feel as overly uncomfortable under most circumstances.

I don't like to get shocked either but like the potential problems and dangers associated with ground probes even less.

 

[amc78cj7]

Old thread, new troubleshooting question:

I have a 60 gallon with a fuge below.

All the power runs off a single 120V ground fault outlet in the following way:

One outlet is connected to a 9-plug APC power backup. Receiving power from this are 3 koralia powerheads that are in the main tank, a 1200 GPH return pump in the fuge, a skimmer pump in the fuge, a heater in the fuge, and a nano powerhead in the fuge.

The other outlet feeds a Reefkeeper lite that is connected to a single PC4. Connected to the PC4 are 2 x 1.1mL BRS dosing pumps. A third middle outlet on the PC4 goes to a surge protector power strip that powers 2 Reef Radiance DM-165e LED lights, and one small LED light over the fuge (timed by the PC4).

Last night I started getting zapped, so I followed the instructions from the first post of kcress on page 1 of this thread. I used a IDEAL 61-360 multimeter and have confirmed that I get 120V when plugged into the extension cord, and ~1V when plugged into the ground.

I found that if I unplug one of my Koralia then my voltage in the tank water drops 57V. If I unplug one of the other Koralia then I get another drop of 25V. The third powerhead had no effect. The unplugging the return pump causes a 4V drop, and unplugging the heater causes a 2V drop.

Going back to 3V, if I unplug the APC powerbackup from the wall or press the green power button on the front to turn it off I go from 3 to 0.

With just the 2 koralias unplugged I am at 3V. When I pull the koralias from the water I'm down to 1.4V Problem solved, right? Well this is where it gets weird.

While at 1.4V with everything plugged in except the 2 Koralias; if I unplug the Reefkeeper light from the wall then I get an increase to 39.5. So I plug the reefkeeper light back into the wall and it drops to 1.4V. Then I unplug the two dosing pumps from the PC4 and nothing happens, but when I unplug the powerstrip from the PC4 it jumps back up to 39.5.

I plug the powerstrip back into the PC4 and am back to 1.4V. When I unplug one of Reef Radiance plugs from the strip then it stays at 1.4V, but if I unplug both reef radiance plugs, either at the powerstrip or at the light on top of the tank, then it jumps to 40. It seems like the reef radiance light is acting like a ground.

 

[uncleof6]

Why would you stick your hand in a second time, when you got "bit" the first time? That is asking for a Darwin Award...

Also, the National Electric Code prohibits the use of extension cords, for any use, longer than 3 hours.

Induced voltage from the inductive loads. And you are using an APC that is not intended nor designed to run inductive loads, it is intended to run resitive loads, and does not provide an adequate sine wave to properly run AC motors. That is part of the problem.

Pin to pin on the recepticle: Hot to neutral: 120VAC. Hot to ground: 120VAC. Neutral to ground: 0VAC. If you have a voltage of 1VAC from hot to ground, (1volt difference between the hot and ground): you have a hot ground, and the system is extremely dangerous, and the GFCI could care less. So it depends on how you are testing this stuff. You need to be specific where you are getting the 1VAC and how you are getting it.

Testing for "stray voltage" does not always paint an accurate picture of what is going on in the tank.

I do feel you need to do some better electrical work on this tank, and there may well be a problem with the system. I also feel that your outlet is overloaded. For heck sake, don't stick you hand in the tank to see if you get bit again. At 57VAC potential in the tank, you can be killed and the GFCI will most likely not care, though the only thing it will protect you from is a damaged heater, assuming you don't have a damaged powerhead/pump cord. A powerhead/pump cord shorting from hot to ground, sans the APC, the GFCI would trip. That could use some further explanation. It is not worth the risk.

 

[amc78cj7]

I think you misread.

1) I only stuck my hand in once and got zapped. Then I moved to the multimeter
2) I am only using the extension cord for use of the multimeter per the post by kcress. It has been plugged in less than 3 hours.
3) The tank is currently at 1.4V which is right around background for this multimeter per the original test.
4) If I unplug my light I jump to 40VAC, but with light plugged in I'm at 1.4VAC so the light is acting like a ground.
5) I have as many accessories as probably most aquariums, and perhaps I should consider running an extra 2-4 plugs straight from the breaker box? How else would you plug in 4 powerheads, 3 lights, 2 pumps, 1 heater, 2 dosing pumps and 1 ATO (forgot to test that)? That's 13 plugs. They can't all have independent plugs.

 

[amc78cj7]

1) I'm at 1.4 VAC
2) I unplug both light cords and I jump up to 40VAC
3) I unplug everything one-by-one and nothing reduces it
4) The only thing that reduces it back to 1.4 VAC is to unplug the APC backup power supply from the wall, even though unplugging each component from the APC does nothing.

Could the APC be causing a voltage leak through multiple components that don't individually cause a problem? The APC itself is not directly attached to the aquarium???

 

[uncleof6]

I think you misread.

1) I only stuck my hand in once and got zapped. Then I moved to the multimeter

That is a good thing. Withdraw the comment on sticking hands in.

2) I am only using the extension cord for use of the multimeter per the post by kcress. It has been plugged in less than 3 hours.

I read that post a long time ago. I have yet to find anyone that can actually test for stray voltage in a tank, and get an accurate picture of what is going on. Withdraw the comment concerning the use of extension cords.

3) The tank is currently at 1.4V which is right around background for this multimeter per the original test.
4) If I unplug my light I jump to 40VAC, but with light plugged in I'm at 1.4VAC so the light is acting like a ground.

Does that really sound reasonable to you?

40VAC is considered "low voltage" and it is not sufficient umpf to cause any harm. ON the other hand, 57VAC is. So where did the 57VAC come from? I am not trying to blast you here, trying to get a handle on exactly what you have going on.

5) I have as many accessories as probably most aquariums, and perhaps I should consider running an extra 2-4 plugs straight from the breaker box? How else would you plug in 4 powerheads, 3 lights, 2 pumps, 1 heater, 2 dosing pumps and 1 ATO (forgot to test that)? That's 13 plugs. They can't all have independent plugs.

I am just guessing, becasue I don't have hands on with your system. Add everything up and see what you have. The pump should be on a seperate circuit, at the very least. Just good practice due to inrush current.

The electrical code calls for no more than 80% of the circuit rating. Assuming it is a standard residential occupancy, the circuit is rated at 15amps. That means it is overloaded if the amperage is above 12amps.

Yes I would cut in a quad box, and recepticles. If for no other reason, than to split the load between 2 GFCIs. I would want a second circuit pulled in as well.

 

[uncleof6]

1) I'm at 1.4 VAC
2) I unplug both light cords and I jump up to 40VAC
3) I unplug everything one-by-one and nothing reduces it
4) The only thing that reduces it back to 1.4 VAC is to unplug the APC backup power supply from the wall, even though unplugging each component from the APC does nothing.

Could the APC be causing a voltage leak through multiple components that don't individually cause a problem? The APC itself is not directly attached to the aquarium???

Yes, really should not be using it anyway either way.

 

[amc78cj7]

Thanks for the advice on adding another GFCI. I'll have to see how I can do it since I have a tank and stand against the wall now.

Regarding the 57VAC, that was from one of the 2 Koralias that have now been removed from the tank. With the 2 "leaky" Koralias removed from the tank I am left with 1.4VAC with everything plugged in, and 40VAC if I unplug the LED lights on top of the display tank.

 

[uncleof6]

Well at least it can be considered a low enough voltage to be 'safe,' I would really look into the anomally with the lights, that should not be.

 

[amc78cj7]

New set of tests tonight using the multimeter as described previously.

First I unplugged everything from the wall, then used a outlet tester from Lowes and determined that the GF outlet is wired correctly and has a good ground on both outlets.

For shits and giggles I completely removed the Reef Radiance lights from the tank area and also got rid of the APC battery backup. They are in other rooms so they can't even have a field effect...

Next I started plugging components in one by one and watched the VAC climb with each one. Here is a list of the findings:

Aquarium Component_________________VAC_____Change (V)
Background (nothing plugged into wall)___5.3_______0
Powerstrip into wall___________________6.0______0.7
Reefkeeper Lite/PC4 into wall___________7.8______1.8
Both 1.1mL dosing pumps into PC4 (off)___7.3_____-0.5
Fuge Powerhead_____________________12.7______5.4
Skimmer Pump_______________________31.4_____18.7
Heater______________________________34.0_____2.6
Return Pump________________________38.8______4.8
Fuge LED light_______________________39.9______1.1
Display Tank Powerhead_______________40.8______0.9
Tunze ATO__________________________41.8______1.0

Next I plug in the Reef Radiance LED and VAC returns to 5.3.

It seems that each of my components is adding a small amount of stray voltage to my water. The most significant is the skimmer pump which accounts for 18.7 Volts (would you keep it or replact it?)

The Reef Radiance LED, for whatever reason, appears to be acting as a capacitor to buffer and store the 36.5 VAC caused by all the other components combined. Does this make sense?

 

[uncleof6]

New set of tests tonight using the multimeter as described previously.

First I unplugged everything from the wall, then used a outlet tester from Lowes and determined that the GF outlet is wired correctly and has a good ground on both outlets.

For shits and giggles I completely removed the Reef Radiance lights from the tank area and also got rid of the APC battery backup. They are in other rooms so they can't even have a field effect...

Next I started plugging components in one by one and watched the VAC climb with each one. Here is a list of the findings:

Aquarium Component_________________VAC_____Change (V)
Background (nothing plugged into wall)___5.3_______0
Powerstrip into wall___________________6.0______0.7
Reefkeeper Lite/PC4 into wall___________7.8______1.8
Both 1.1mL dosing pumps into PC4 (off)___7.3_____-0.5
Fuge Powerhead_____________________12.7______5.4
Skimmer Pump_______________________31.4_____18.7
Heater______________________________34.0_____2.6
Return Pump________________________38.8______4.8
Fuge LED light_______________________39.9______1.1
Display Tank Powerhead_______________40.8______0.9
Tunze ATO__________________________41.8______1.0

Next I plug in the Reef Radiance LED and VAC returns to 5.3.

It seems that each of my components is adding a small amount of stray voltage to my water. The most significant is the skimmer pump which accounts for 18.7 Volts (would you keep it or replact it?)

The Reef Radiance LED, for whatever reason, appears to be acting as a capacitor to buffer and store the 36.5 VAC caused by all the other components combined. Does this make sense?

The ground does not have anything to do with the operation of the GFCI, there does not need to be an equipment ground for the GFCI to work properly.

I would pull the skimmer pump, and find someone with a megohm meter, and have the cord checked for a high resistance short, and/or replace the cord.

Zero your meter at the background voltage. (5.3VAC) that is the salt water. Salt water behaves as an electrolyte.

No the led thing does not make sense. Without a direct path to ground, the induced voltage in the tank will not drop to zero, or 1.4VAC, or the "background" voltage of 5.3VAC, but the 5.3VAC would drop to zero also. I don't have hands on the fixture, so anything I say would just be a shot in the dark.

I would take the fixture to a "non-hobby" or "real" electronics technician and have him go through the fixture. Hobby fixtures are not required to meet any type of standard at all, and quite frankly I find them to be a huge disappointment quality wise. Same for the rest of your system. Have an electrician go through it. None of us here have hands on the system. What I would find, may
not be what you are finding/seeing.

But the APC is not for running an aquarium, it is for running computers. Huge difference, till you get up in the $1000 + range. Better is to get an auto start gas/propane generator, that will run your fridge as well.

I know where most of the voltage is coming from, it is induced by the inductive loads (motors, any HID lighting,) and is harmless without a path to ground. Below 40VAC does not have the umpf anyway. The heater is purely a resistive load, and should not impress a voltage on the water, but electricity is "magic" so strange things can happen. Voltage can be impressed on the tank by fluorescent lamps in the next room. Other possibilities are harmonics (dirty power) from "lousy" house wiring, bundling wires/cords together, and other such ethereal anomalies.

 

[amc78cj7]

I have 63.6 microAmps (0.06 mA, 0.00006A) in the system with 41.5 volts. The APC is gone. My house is also hardwired to hook up to my gas generator when we lose power
(1-2 times a year), but it was often the alarm from the APC that would wake me up in the middle of the night to let me know we lost power. Maybe I'll hook it into another outlet (say my computer) to keep the alarm.