Stray Voltage - Anyone have readings for comparison?

[+boognish]

Several months ago, while changing a filter sock, I could have sworn I received a tiny shock when reconnecting the PVC extension at the bottom of my overflow. I was able to get it to happen that night, but never really noticed it again, so I left it alone. I tested for stray voltage today and I'm getting confusing readings. I am not sure if I should be looking at a problem with the house's ground or the elec system around the tank or both.

I've gone through a few threads on this and several other forums. I read that submersible magnetic pumps act like a generator and will produce stray voltage. How much is normal, I did not find. I assume it would vary with the size of the pump. I read that if a pump were shorted, I would read 120V in the water column, which I am not. The most I read is 32v - 34v.

If you have readings or the availability to get readings, I would be curious to see what results others get. In all of the threads I stumbled upon, I did not find any readings to compare.

House Readings
To test I first tested an outlet used by several pumps and lights on the tank by setting the voltmeter to V~ and sticking the black in the longer ground side and red in the shorter live side. I then tested an outlet on a completely different fuse they both read 121V. I expected 124V.

I moved the red to the 3rd ground hole and received mixed/incosistent readings on different outlets: .77V - 1.3V
So my first question is: Is it abnormal to read a little bit of voltage on the ground like that?

Tank Readings
To test, I insert the black probe in the round 3rd hole of a socket and the red in the tank or sump.

With everything unplugged/off except for the external Reeflo circ pump. All of ther readings below display the actual reading I got which includes this inital mysterious value...

TANK: 4.3V

SUMP: 3.9V

Plugging components back in individually:

• Display:
  • Tunze turbelle
    • TANK: 8.8v (4.5 additional Vs)
    • SUMP: 7.4v (3.5 additional Vs)
  • Vortech MP40
    • TANK: 5.7v (1.4 additional Vs)
    • SUMP: 5.4v (1.5 additional Vs)
  • Tunze wave box (older model)
    • TANK: 6.1v (1.8 additional Vs)
    • SUMP: 5.3v (1.4 additional Vs)
• Sump
  • Koralia Nano
    • TANK: 8.2v (3.9 additional Vs)
    • SUMP: 8.2v (4.3 additional Vs)
  • Chiller pump
    • TANK: 8.3v (4 additional Vs)
    • SUMP: 7.8v (3.9 additional Vs)
  • Sedra 9000 for ASM g3 skimmer
    • TANK: 14.3v (10 additional Vs)
    • SUMP: 14.3v (10.4 additional Vs)

Adding my readings together, I should read 29.9v in the tank and 28.9v in the sump.

My actual readings are 33v in the tank and 31.5v in the sump. (Each reading goes up 1v with all MHs and T5s and assocaited fans on)

Is it normal for EVERY component to add stray volts to the water column or is this an indication of something wrong in the house?

Needless to say, I have left the skimmer unplugged for now while I do some research on this. These are weird numbers and have me a bit confused since the individual numbers do not add up to what I my readings are when everything is running. Any input from the electrically inclined or with experience with any of this is appreciated. I am wondering if I need to focus on an issue with the house ground before any of the tank electrical or if I should focus on the tank electrical.

Some sites recommend using a grounding rod... anyone use one? A ground would give any potential volts a path to ground and therefore cause current, so I'm not sure that is a solution to my problem.

[+o0zarkawater]

What about the other tank? Similar readings over in the front room?

[offroadodge]

just measured my sump, I have 2x6105s, wavebox(new), and a skimz skimmer in the water running with a reeflo hammerhead external running the tank. I could only get 0.71V there. R U sure the circuits u have everything plugged into is grounded? Your tank having 33V would explain a lot of things. And since your other tank is doing good color wise I can only think that the circuit u added for the new tank isn't grounded. Im surprised that its not tripping a breaker. Start looking cause u don't want to burn the house down, and have to put it out with the fish tank.

[jestep]

That seems really high to me. I typically have around 4V in the tank or sump. Normally if there is any actual short into the tank you will read full line voltage. You can't really leak partial voltage, but I've never seen equipment cumulatively induce voltage like this.

[+boognish]

And since your other tank is doing good color wise I can only think that the circuit u added for the new tank isn't grounded.

My Apex/EB8 is the only thing hooked up to the new circuit. It is pushing the MHs, T5s, and a few fans. Funny you mention the colors in the other tank. Some things have decent color, but over all, things are faded in there also.

What about the other tank? Similar readings over in the front room?

I just tested the 75, and its even worse!

45V

Unplugged Koralia: Went down to 40v

Unplugged Maxijet: Went down to 20v

I stopped there...

I guess the question now, is ... Would a bad ground on the house or bad neutral/ground in the 'fusebox' cause every component to add voltage like this?

[jestep]

What sort of voltage meter are you measuring on? I might borrow one just to confirm the readings.

For something like this grounding wouldn't matter. You're not actually shorting something in the tank it's induced voltage in the water from a spinning electronic object.

[+o0zarkawater]

Are you sure you know how to use the multimeter?

[subsea]

What sort of voltage meter are you measuring on? I might borrow one just to confirm the readings.

For something like this grounding wouldn't matter. You're not actually shorting something in the tank it's induced voltage in the water from a spinning electronic object.

In the case of hi voltage transmission lines, magnetic flux from the current in the line induces a magnetic field. I doubt that it would be significiant with the low wattage equipment that we use.

You have done some in depth diagnostics on stray voltage. Before getting in depth with your tank diagnostic, you should investigate the stray voltage on your house ground. To remove that as a source of confusion, I suggest you use an extension cord to a dedicated source with its own seperate ground rod. Before hooking up your tank equipment, validate that the dedicated circuit has no stray voltage on neutral or ground. Then hook up edquipment one piece at a time and check your ground and your neutrel.

Be careful with electricity and salt water. Ask Timfish why I say that.

Patrick

[+boognish]

I did find a couple threads this weekend that have similar issues, but none with resolution. Only one reported readings as high as 35-40 volts. Most only report up to 10 v with everything running. For both threads that I found, they were leaning towards just adding a grounding rod. Since the Skimmer/Sedra seems to be the largest contributor, I will test resistance form the case to the plug to make sure it is ok. I am also looking for an electrician to come by and check the house out. Since my readings in both tanks are much higher than anyone else is getting or would expect from the pumps, but not high enough to indicate a short, I will start with the house.

[bigmike015]

When you test the sump and tank should it read 0 on the volt meter? I just tested mine from the main power supply to all my plugs and stuck the black lead in the sump and got 65 volts. I dont know what any of this means

[jestep]

Something else has to be going on. It should be under 10V whether in the sump or the tank. It is normal to have a few volts induced naturally. I have about 3 in my FW tanks and 4'ish in my SW tank with everything running. Saltwater is a better conductor so it naturally ends up with more induced voltage than freshwater.

I am assuming you are all testing on the AC setting and that your meter doesn't have an adjustment scale. Mine has 3 AC settings 200V, 500V and 1000V. If you have it on a lower or higher setting the reading changes accordingly. Just ruling out the obvious.

Also, make sure to test your meter in an outlet so that you can verify it's reading ~110.

[bigmike015]

Here is what I'm using, putting the black on a ground hole in a plug and the red into the tank. Are those the right settings

[jestep]

Yeah. Definitely the right settings. Digital is pretty hard to mess up anyways. Did you test it on a wall outlet as well?

[bigmike015]

yes, and im getting 119 out of the wall. When i use the black ground hole do i use any particular ground hole or can i bring a ext. cord and use the ground off that? I am fixing to do a few more test to see what i get.

[bigmike015]

Ok so just did another test. Got an extension cord used the ground hole on it and insereted the red into the water.

When i tested water in the sump with everything running i was getting 29.4.

With everything off on the Reefkeeper 2 getting 36.4

when i unplugged the main power source to the tank so nothing was getting power i got 3.6

What do i need to do?

[bigmike015]

I just woke up this morning and when i checked to see what my tank was getting i am getting 64.5v What does that mean? Is that bad. What do i do?\

[jestep]

If you're not noticing any negative effects in the tank, I wouldn't do anything.

You could go the grounding probe route. I'm against these especially in situations like yours as they will cause current flow in the tank. Right now you just have an induced voltage but there's no path to ground and thus no current is actually flowing in the tank.

There was a good discussion here about grounding probes a while back. If done correctly they're designed to protect a human from being shocked if a piece of equipment is fully shorted into the tank. The downside is that they protect the human at the potential expense of everything in the tank because you may not be around when something shorts and all of the pumps and heaters are shut off. Definitely worth looking at the thread. There's nothing wrong with them if it's understood what they can and cannot do. Just not worth the risk IMO, but I do check my tank monthly for shorts.

[bigmike015]

OK thanks, I just wanted to make sure everything in my tank wasn't going to fry.

[+o0zarkawater]

Neato.

My tanks running at 32V with 2 mp10, skimmer pump, fuge pump, and a tunze 6025.

My tank looks GREAT and I have my arms in it all the time, even when standing in pools of water.

Go figure.

[+boognish]

Thanks - Other's readings is exaclty what I was looking for. While it sets my mind at ease a little to see others with similar findings, it does not get me any closer to finding out what's up with my corals (both sps and softies) fading, and frogspawn not extending fully and receding, etc... Might be new tank syndrome even though its about a year old, but it can't hurt to make sure all the t's are crossed and I's are dotted.

I haven't had an electrician out to make sure I don't have anything wrong with my house wiring. I am also not following best practice with some of my wiring, which I will remedy this week. No more daisy-chaining cheap power strips. I guess I should move the powerstrip that is hanging over my sump that says "do not use in aquariums" also.

Grounding Post... I'm still on the fence about this one since all my research comes to down to exactly what jestep said.

[jestep]

I didn't think of the daisy chain issue. Post what you end up with after switching. Do you have any very high wattage pumps? Also, do you by chance have a kill a watt meter so you can test your running amperage? You have to test current in-line, so it's difficult to do safely with a multimeter on a normal circuit. It's on a controller that would tell as well.

When you daisy chain power strips or even use extremely long or low quality extension cords you end up with higher current because the circuits have more internal resistance, through more wire or through the connections between components such as one plug into the outlet of the next power strip. Since the resistance of the wire or the power strips is going to precede the pumps in the tank, everything in the tank will run at a higher current than it normally would.

When speaking of inductance, the voltage being induced is mathematically related to the rate of change in magnetic flux. In an AC circuit if you have more current, the rate of change is higher than on low load circuits with the same voltage. This could definitely increase the induced current in the tank, although it still seems that it would be less than what you all are reading.

[+o0zarkawater]

I didn't think of the daisy chain issue. Post what you end up with after switching. Do you have any very high wattage pumps? Also, do you by chance have a kill a watt meter so you can test your running amperage? You have to test current in-line, so it's difficult to do safely with a multimeter on a normal circuit. It's on a controller that would tell as well.

When you daisy chain power strips or even use extremely long or low quality extension cords you end up with higher current because the circuits have more internal resistance, through more wire or through the connections between components such as one plug into the outlet of the next power strip. Since the resistance of the wire or the power strips is going to precede the pumps in the tank, everything in the tank will run at a higher current than it normally would.

When speaking of inductance, the voltage being induced is mathematically related to the rate of change in magnetic flux. In an AC circuit if you have more current, the rate of change is higher than on low load circuits with the same voltage. This could definitely increase the induced current in the tank, although it still seems that it would be less than what you all are reading.

[jestep]

Sorry basic electricity came flooding back.

[+boognish]

Also, do you by chance have a kill a watt meter so you can test your running amperage? You have to test current in-line, so it's difficult to do safely with a multimeter on a normal circuit. It's on a controller that would tell as well.

I do measure what all the lights and fans pull via the Apex controller, but the pumps and powerheads are intentionally on a separate circuit and just plugged into whatever I could reach to wherever I needed it. I plan to eventually get another EB8 for the pumps, etc that need to be controlled via the apex, but for now, I cannot measure what I'm pulling. I will definitely post my readings after getting rid of the powerstrips, etc to see if that makes a difference.

I did some preliminary investigation into the way my house is wired and found something that seems a bit unconventional (if not wrong)...

The main elec meter is at a shared box between houses. I assume the grounding rod is there because I have a thick copper ground wire coming out of the ground by my house on that side instead of a grounding post. It goes into the house between the brick and slab. On that same side is the first box. I could not see where this wire goes since its into the side of the house and not a box, so I tested ohms between the outside box's ground and neutral busses and that copper wire coming up out of the ground.

Outside box: By testing ohms between the incoming neutral and ground bus, I can tell I have continuity between the inside and outside boxes (GREEN)

However, I get nothing between the incoming neutral bus and that copper wire. I also get nothing between the outside box's ground bus and that copper wire.

I'm no electrician (I did stay at a Holiday Inn last night), but it seems like my entire house is not grounded. I have continuity between the two boxes along the GND/Neutral, but between neither of those and the grounding wire. My next test will be to get a wire and essentially 'jump' from that wire to the outside ground bus where I would assume it should go, then test my ground and readings from the tank and outlets in the house.

Nothing like a crash course in all the stuff my dad drilled into me, but I never listened to as a kid...

[esacjack]

do you have a grounding probe? also, do you have a probe for your tank? are you using a GFI outlet? Are you using any other type of active probes in the tank? I.e. temperature, ph, etc? Lastly, do you have a grounding rod, grounding plate, or some kind of earth ground? Your copper should be attached to your Earth ground somewhere around the house. Generally its outside by the breaker close to where your cable/phones are installed.