Testing for stray voltage

[magicwhistle]

Had 2 fish die about 2 weeks ago and it was suggested on here I use a grounding probe and measure for voltage.

Wasn't sure where to post this but I'm not sure if I'm measuring the voltage correctly.

Basically have the blackwire in the ground hole of an outlet and then dip the red prong into the water.

Doing that on V squiggly mode gives me ~ 4V. Which I assumed was fine and is just induced current.

Now how do I measure current? When I set the multimeter into the "A straight line/squiggly line" and have the same set up (black prong grounded red in tank) I get 0.013. On the side it says DC. Not sure what this means or if I'm using it correctly.

 

[magicwhistle]

Ok I just noticed if I press 'select' while in the current mode it switches between AC and DC. In AC mode there's a lot more current like 0.5A and in DC mode right now there's like 0.1A in the display tank. Is this indicating faulty equipment somewhere?

EDIT: Actually I'm not so sure now. I unplugged everything in the display tank and it still shows the DT has 0.3A in AC mode...but there is literally nothing plugged in that's inside it currently.

EDIT AGAIN: So I unplugged everything in the tank and sump and eventually get a reading of 0A. However when I turn on literally ANY component I get amp readings... Turn on the wavemaker and it goes up 0.1A turn on pump another 0.1A the heater is like 0.2A and the pump for my media reactor is another 0.1-2A. Voltage is around like 40V and goes down around 10V for each component unplugged...

 

[magicwhistle]

Here’s the readings to make sure I’m doing this correctly.

Also I’ve tried a few different grounds including the screws on the light and a daisy chain outlet on the light. All give similar readings.

So to me these are saying “40Volts AC” and “0.5A AC”. The weird thing is both voltage and amperage go up even when I turn things on that aren’t in the water of the tank at all... like I turn on the lights the amperage and voltage both go up.

 

[reef_ninja]

Electrical stuff completely eludes me and confuses the crap out of me. With that said, from what I've read, it sounds like any meter measurement over zero may indicate stray voltage.

If Im wrong......atleast you got yourself another bump.

 

[magicwhistle]

Electrical stuff completely eludes me and confuses the crap out of me. With that said, from what I've read, it sounds like any meter measurement over zero may indicate stray voltage.

If Im wrong......atleast you got yourself another bump.

Yeah, that's what I initially thought too reading a bit online about it though and I'm confused now lol.

I installed the ground probe and now I get practically 0V and 0A. Does this mean the tank is safe? I'm genuinely confused on how something like the lights with no wiring in the tank is adding current to the tank. The voltage makes sense since the wiring runs near the tank wall.

And it's not like it's just randomness or an error since it seems highly correlated to whats plugged in and right now it's 0 with the grounding probe installed.

 

[Pistondog]

we should all be using gfci outlets for aquarium equipment.

 

[magicwhistle]

we should all be using gfci outlets for aquarium equipment.

I live in an apartment so can’t really change out the outlet.

Are there plug in GFCI outlets? Like a power bar?

 

[Dom]

Voltage is pressure. If you have stray voltage in your tank, you can think of your tank as a battery. You won't measure any current until you put in a grounding probe. A ground probe "completes the circuit, giving voltage a completed path to travel. THATS when you will measure current.

 

[Dom]

I live in an apartment so can’t really change out the outlet.

Are there plug in GFCI outlets? Like a power bar?

You can go to Home Depot and buy an ARC FAULY / GROUND FAULT outlet, install it in a single gang box, put a cover over it with a cord to plug into the outlet in the apartment.

Think of it as an extension cord with a GFI outlet on one end.

 

[magicwhistle]

Voltage is pressure. If you have stray voltage in your tank, you can think of your tank as a battery. You won't measure any current until you put a grounding probe. A ground probe "completes the circuit, giving voltage a completed path to travel. THATS when you will measure current.

Right. So when I have the black probe grounded isn’t that what’s happening? It’s measuring current that’s passing through the tank?

My understanding is that electronics in the tank that create magnetic fields induce a bit of voltage. But there shouldn’t be any current. Or is that wrong. Is the current just part of the induced voltage and fine.

 

[rwreef]

First, yes you test the water for stray voltage by (black probe) into ground prong of receptacle and red probe in water. Meter set to 120v AC

You should be able to turn on/off loads and see this value increase/decrease or stay flat. Measuring current will require you to break the circuit and get between nodes to see current in the tank. Adding a ground probe will allow you to see any leakage current to ground.

Yes, get a GFCI protected power strip and use a ground probe in the tank.

Note..10 mA is a good shock...100 mA can be deadly. This also depends on the Voltage "pushing" the current.

 

[magicwhistle]

First, yes you test the water for stray voltage by (black probe) into ground prong of receptacle and red probe in water. Meter set to 120v AC

You should be able to turn on/off loads and see this value increase/decrease or stay flat. Measuring current will require you to break the circuit and get between nodes to see current in the tank. Adding a ground probe will allow you to see any leakage current to ground.

Yes, get a GFCI protected power strip and use a ground probe in the tank.

Note..10 mA is a good shock...100 mA can be deadly. This also depends on the Voltage "pushing" the current.

So the current that is being measured is something different?

Every single item I unplug reduces the voltage. Nothing unplugged causes it to stay flat. Even the lights and a small LED light for in cabinet.

 

[rwreef]

So the current that is being measured is something different?

Every single item I unplug reduces the voltage. Nothing unplugged causes it to stay flat. Even the lights and a small LED light for in cabinet.

Sounds correct, removing loads will drop your value. Flat meant if it was at or near zero.

 

[Pistondog]

I live in an apartment so can’t really change out the outlet.

Are there plug in GFCI outlets? Like a power bar?

I bought this one since I recognize the brand and it is ul/csa.
Don't go cheap on a a Chinese off brand to save $10.

 

[magicwhistle]

I bought this one since I recognize the brand and it is ul/csa.
Don't go cheap on a a Chinese off brand to save $10.

Sweet. Thank you! Just to make sure since the amazon thing isn't working for me (I googled the code) it's the Leviton GFA15-6 15-Amp 120-Volt GFCI device right?

Another dumb question. If I plug a standard powerstrip into this everything downstream of the GFCI outlet will be protected correct? And if one item creates a fault then the entire strip will be off.

So should really get 2 to split up the flow in case something trips it?

 

[magicwhistle]

Sounds correct, removing loads will drop your value. Flat meant if it was at or near zero.

Awesome. Thank you for the info.

So is it safe to assume that this is just induced current?

I'm still going to buy some GFCI plugs but will have to wait for those to arrive.

 

[Pistondog]

Sweet. Thank you! Just to make sure since the amazon thing isn't working for me (I googled the code) it's the Leviton GFA15-6 15-Amp 120-Volt GFCI device right?

Another dumb question. If I plug a standard powerstrip into this everything downstream of the GFCI outlet will be protected correct? And if one item creates a fault then the entire strip will be off.

So should really get 2 to split up the flow in case something trips it?

Yes sorry, meant to edit, all downstream stuff is protected.
I think 1 is enough, unless you need more than 10 amps.
If it is tripped, there is a fault. This should be infrequent.
Why 2? Can you split the loads so if either trips things are still ok?

 

[magicwhistle]

Yes sorry, meant to edit, all downstream stuff is protected.
I think 1 is enough, unless you need more than 10 amps.
If it is tripped, there is a fault. This should be infrequent.
Why 2? Can you split the loads so if either trips things are still ok?

Yeah exactly. Would like to split the powerheads from everything else at a minimum to ensure theres water movement. Either from the return pump or if that trips then from the powerheads.

So regarding grounding probes then. From what I understand in this thread current only exists when the voltage is given a ground. So why should we ground the tank? Wouldn't that be allowing a constant current to flow through the tank that otherwise wouldn't be there? Is that safe for the animals? If the readings I took were correct (0.5A) isn't that kind of crazy to toss fish into?

I get that it makes it safer if there is a stray voltage rather than induced voltage and you stick your hand into it but wouldn't using a GFCI protect against that anyway?

 

[Pistondog]

Yeah exactly. Would like to split the powerheads from everything else at a minimum to ensure theres water movement. Either from the return pump or if that trips then from the powerheads.

So regarding grounding probes then. From what I understand in this thread current only exists when the voltage is given a ground. So why should we ground the tank? Wouldn't that be allowing a constant current to flow through the tank that otherwise wouldn't be there? Is that safe for the animals? If the readings I took were correct (0.5A) isn't that kind of crazy to toss fish into?

I get that it makes it safer if there is a stray voltage rather than induced voltage and you stick your hand into it but wouldn't using a GFCI protect against that anyway?

Get the gfci cord, that will tell you if there is a problem.
Otherwise you may be chasing ghosts with induced voltage readings.

 

[rwreef]

Yeah exactly. Would like to split the powerheads from everything else at a minimum to ensure theres water movement. Either from the return pump or if that trips then from the powerheads.

So regarding grounding probes then. From what I understand in this thread current only exists when the voltage is given a ground. So why should we ground the tank? Wouldn't that be allowing a constant current to flow through the tank that otherwise wouldn't be there? Is that safe for the animals? If the readings I took were correct (0.5A) isn't that kind of crazy to toss fish into?

I get that it makes it safer if there is a stray voltage rather than induced voltage and you stick your hand into it but wouldn't using a GFCI protect against that anyway?

You want to give the current a safe path back to ground. You are not a safe path...aka you touch water and create a ground path