Stray voltage, and acceptable levels

[Wiz]

I am very new to electricity. I measured AC volts at 200. I did not measure anything else. I did do the unplug everything and one at a time. Each one seemed to do two to three volts. Two of them we're like 20 volts. But I replace those too and still have the issue. The only thing on a timer is the lights. And they are on a separate strip that is on a separate outlet that does not touch the tank except for the wires touching the glass. I examined the wires and can see no brakes or abrasions

 

[Wiz]

If I shut thegfci that powers all of the water stuff off the volts immediately dropped. But there is not one plug-in there that will do the drop on its own. It is only when I shut the thing entirely off. I even tried eliminating the GFCI with no effect. And trading out the power strip that's plugged into it with no effect.

 

[Brew12]

There is no need to check anything with DC. AC will get everything you are looking for. First, you cannot induce voltages with DC and second, you don't have any DC loads on your aquarium other than possibly your ATO pump.

I'm not sure exactly how you are set up but without knowing more, this is what I would suggest. Get another portable GFCI unit. Plug in a powerstrip to each. Split your critical loads between the two power strips. Then buy and install a ground probe. This way you can completely eliminate the possibility of your issue being stray voltage and still have some reliability if your GFCI trips.

 

[USMC4Life]

@Brew12 I am talking about AC inducing DC voltage in the tank. Not DC.

 

[Wiz]

I've got it to 20v. But can't figure the problem. When I lay my arm across the top of the fuge, only contacting both sides of the black trim it drops about 4v. If I unplug the light power strip it shoots up to 80. Sooooo wierd

 

[Brew12]

I've got it to 20v. But can't figure the problem. When I lay my arm across the top of the fuge, only contacting both sides of the black trim it drops about 4v. If I unplug the light power strip it shoots up to 80. Sooooo wierd

Are you sure your meter isn't auto ranging and that it isn't going to 80mV instead of 80V?

 

[Wiz]

Are you sure your meter isn't auto ranging and that it isn't going to 80mV instead of 80V?

It's on the 200v setting and ranges from 1.2 to 80-90v at different times. I think I'm Reading it right. Just the idea that it's affected by the lights is odd. Isn't it? The gfci power strip is on the right of tank. The power strip for the lights is on the left. Nothing on that strip touchs water. How could it affect it

 

[Wiz]

And I check it by plugging it into the wall and reading 120

 

[Brew12]

It's on the 200v setting and ranges from 1.2 to 80-90v at different times. I think I'm Reading it right. Just the idea that it's affected by the lights is odd. Isn't it? The gfci power strip is on the right of tank. The power strip for the lights is on the left. Nothing on that strip touchs water. How could it affect it

Sounds like you are reading it correctly.

Inner Geek Alert:

When the first electric grids were being formed to rather famous individuals, Tesla and Edison, were competing to get their preferred method of generation to be adopted. Edison wanted DC because the voltage was easier to regulate, it was safer, and the technology was more mature. Edison rather disturbingly electrocuted an elephant using AC current to try and make his case. Tesla won the battle of the currents anyway, and the AC distribution system was born. Why did he win? Transformers. The Autobots and Deceptacons came.. uh wait.. wrong story. The largest single power loss in a distribution system is due to heat generation from current. The heat produced is equal to the square of the current times the resistance (P =I*I*R). Another power equation is P=1.732*V*I*pf. if you raise voltage, you can lower current and greatly reduce your losses. With DC generation we would have needed a power plant every few city blocks. Thanks to transformers we can raise voltage to very high levels and distribute power over long distances with minimal losses.
In its most simple form a transformer is nothing more than a steal core with 2 separate coils wrapped around it. The proximity of the two coils allows the magnetic flux from one winding to generate voltage, through induction, in the other winding. By controlling the number of turns in each coil we can control the output voltage of the second winding.

Ok, back to the subject at hand. Why does the light matter when it isn't touching the water? A transformer is proof that if you have an AC current source near a conductor, it will generate a voltage. Salt water is a conductor. If the power cord of any electrical component runs outside and along the tank walls it will induce a voltage into the water. If you have a power cord that runs next to part of a power cord that runs next to the aquarium you can induce a voltage in the aquarium. As long as you have a magnetic field within the water of the aquarium, and relative motion between the magnet and the water, you will induce a voltage.

One of my biggest concerns is that you may be seeing these big fluctuations not because of the induced voltage, but because of a problem with your ground. If your ground prong isn't properly bonded to both earth, and the transformer neutral the feeds your house, you can get some very odd readings. A good way to test the ground within your house is to run a 3 prong extension cord from an outlet on a different circuit to where your tank is. Then use your meter set for resistance to check the number of ohms between your power strip ground and the ground on the extension cord. You should get less than 1 ohm.

 

[3mm3]

Do you have any ATO float switches?

 

[Wiz]

No ato or floats.

Leds come on at 10 and start ramping. T5s and cfs on fuge come on at 12. I tested at 12 it was 1.1v. Tested at 2 it was 11.9v. Must have something to do with the t5/cf strip.

 

[Wiz]

But unplugging it makes it go higher.

 

[Wiz]

Just tested at 13.7v. It is raising as the time passes. Why would that happen?

 

[Brew12]

Try taking a resistance reading from your neutral prong (larger on) to your ground. You may have something going on there.

You can also start monitoring your household voltage. Measure from hot to ground (or neutral) each time you check your tank.

 

[Brew12]

Ok, I feel a bit dumb.. one more thing to try. Take a voltage reading from the hot prong on your lighting power strip to the hot prong on your aquarium load power strip. I expect you to see 22oV.

 

[Bruce Burnett]

power supplies for led lights and wave pumps change the frequency of the ac power and they have filtering circuits to reduce interference and induced voltage. When they have a heavy load such as lights or pumps being on higher settings, this can cause power supplies to get too hot and the circuits to break down. It can be difficult to isolate by plugging and unplugging items. I had erroneous ph reading that would fluctuate and I checked voltage in the water which had 28 volts. Unplugged everything and it went away. Started by plugging everything in one at a time and would get no reading came back an hour late and all screwed up. Unplug everything one at a time. Went away when I unplugged the same pair of Jebao pumps. Figured it was the controller did not change. Switched out pump that seemed to make a change. the problem still was their. Finally changed out power supply. What made so weird and hard to figure out is it was not there all the time and did not completely go away or come back all at once. When I switched around power supplies I found if I keep the pumps on low setting or alternating mode the power supply stayed cooler. If I ran both pumps full power it did not take long and my ph meter went weird. The filtering circuit was breaking down with the heat. This can also happen with Led lights and why it may happen same time each day.

 

[Brew12]

Lots of possible options. The reason I asked you to take a reading between hots on the power strips is to see if the voltages could be canceling each other out when both are on.

This is how most homes are wired. You actually have 1 transformer winding that is "center tapped". This center tap is grounded and is also where your neutrals bond to. Either hot leg to neutral gives you 120V. Going from hot leg to hot leg gives you 240V.

If you have a voltage induced by equipment powered off of 1 120v leg it can be canceled out by the voltage induced by equipment powered off of the other 120v leg.

 

[Bruce Burnett]

Lots of possible options. The reason I asked you to take a reading between hots on the power strips is to see if the voltages could be canceling each other out when both are on.

This is how most homes are wired. You actually have 1 transformer winding that is "center tapped". This center tap is grounded and is also where your neutrals bond to. Either hot leg to neutral gives you 120V. Going from hot leg to hot leg gives you 240V.

If you have a voltage induced by equipment powered off of 1 120v leg it can be canceled out by the voltage induced by equipment powered off of the other 120v leg.

This true if you are using outlets on opposite side of transformer center tap. I would recommend only using power from one side of the load. Even though 200 volts is common in Europe I would try to keep the voltage around saltwater as low as possible. When possible I would recommend people have a dedicated outlet on a gfi breaker on it's own ground. Not all of us can do that but it is best to keep everything on same 120 volt circuit.

 

[Pola0502ds]

@Brew12 I am having the same exact issue, i am getting 22 stray volts in my tank per multimeter. I had been talking to bulk reef supply and neptune systems about this over the past 2 days and they don't like to use ground probes to solve the problem because they do mask any serious problems if there was one. I know you are in favor of using grounding probes so how do you solve this problem? If you always use a grounding probe you would never know about and locate the problem. What is the way around this?

 

[Brew12]

@Brew12 I am having the same exact issue, i am getting 22 stray volts in my tank per multimeter. I had been talking to bulk reef supply and neptune systems about this over the past 2 days and they don't like to use ground probes to solve the problem because they do mask any serious problems if there was one. I know you are in favor of using grounding probes so how do you solve this problem? If you always use a grounding probe you would never know about and locate the problem. What is the way around this?

Using a grounding probe in conjunction with GFCI will never mask a problem, it will only solve them.

There is a huge amount of bad information regarding ground probes in aquarium. It seems like the bad information resolves around 3 main points. First, people don't understand that fish are less conductive than the sea water they live in and don't understand the impact of this. Second, people assume that it takes the same amount of current to drop an induces voltage as it does a traditionally supplied voltage. This is completely false. It takes fractions of an amp to eliminate an induced voltage from an aquarium. Third, people assume that only current impacts fish. This is true of people but people don't have voltage sensors in our heads and lateral lines.

I really need to write an in depth and technical article about this.