Stray voltage

forced4 · Post by **forced4** » Mon Oct 14, 2013 4:42 pm

Hi everyone!

I noticed a bit of a tingle on a cut on my index finger when I was cleaning things yesterday and decided to check for stray voltage. I am not that great with electrical stuff so I need advice.

I used my multimeter with the positive probe in the water and negative in the ground of my outlet. I appear to have 15 volts on the loose. I unplugged everything one by one and the item worth the most voltage (10v) was the ph probe of all things.

I can't get my head around it. Can these leak voltage or am I missing something else? The other 5v is spread out somewhat evenly across all of my equipment. Am I testing for stray voltage correctly? Am I missing something completely obvious before I replace the probe?

Thanks in advance,

Phil

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rimai · Post by **rimai** » Mon Oct 14, 2013 5:51 pm

Are you using meanwell drivers?

forced4 · Post by **forced4** » Mon Oct 14, 2013 5:59 pm

Hi Roberto,

I have retrofit t5 lighting with hep group SI254-58 UNI ballasts x3.

I am using the daylight pwm on the ra to run a single jebao wp-40.

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rimai · Post by **rimai** » Mon Oct 14, 2013 6:02 pm

What happens if you disconnect that Jebao cable?

forced4 · Post by **forced4** » Mon Oct 14, 2013 6:10 pm

It drops ~2 vAC.

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rimai · Post by **rimai** » Mon Oct 14, 2013 7:01 pm

When you were measuring this, did you physically disconnected the pumps from the relay box or just turned it off?

forced4 · Post by **forced4** » Mon Oct 14, 2013 7:03 pm

Toggling at first then physical plug pulls. One by one.

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rimai · Post by **rimai** » Mon Oct 14, 2013 7:12 pm

I'm curious to know if you put the probe in a cup of tank water and measure, if you get the same results.

forced4 · Post by **forced4** » Mon Oct 14, 2013 7:25 pm

Overall voltage has dropped as my lights are all off now.

Probe in tank = 13.6 volts
Probe in air = 2 volts
Probe in cup of tank water = 4 volts.

Another thing I noticed in the client is the ph takes a dramatic downward spike occasionally. I haven't had time to see if that is a trend tied to any equipment or relay. I will try to look into it more tomorrow after work.

As always, I appreciate the support!

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forced4 · Post by **forced4** » Mon Oct 14, 2013 7:29 pm

Oh, fwiw, ph of both the sump and cup is checking identical at 7.98.

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chapboogie · Post by **chapboogie** » Tue Oct 15, 2013 10:35 pm

Watching this.....

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chapboogie · Post by **chapboogie** » Thu Dec 12, 2013 2:28 pm

What was the solution on this?

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chapboogie · Post by **chapboogie** » Fri Dec 13, 2013 4:09 pm

Was there a solution?

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kevingehrke · Post by **kevingehrke** » Fri Jan 03, 2014 2:37 pm

I have this problem too. So I took the ph probe and put it into a different cup of water, and stuck in my pinky and got mildly shocked confirming the probe is the leak.

ReEfnWrX · Post by **ReEfnWrX** » Fri Jan 03, 2014 2:57 pm

Have you guys tried using a grounding probe to ground your aquarium?

I would guess that should prevent the leaking current from affecting your sensors...??

I have found that I almost always get current leak from pumps over time... I've been using grounding probes for the last 2 years because of it

lnevo · Post by **lnevo** » Fri Jan 03, 2014 2:59 pm

I added a grounding probe it did nothing for the .2 offset I see in my pH in the tank vs out of the tank.

Would stray voltage reduce the life expectancy of a probe? Mine is no longer holding the calibration. Its my 2nd probe now on a 1.5 yo tank.

Have a lab grade probe on order.

ReEfnWrX · Post by **ReEfnWrX** » Fri Jan 03, 2014 3:03 pm

Out of curiosity, are you using a pH expansion?

From what Roberto told me, only the pH expansion has galvanic isolation. And from what I have read that should prevent stray voltage from affecting the readings.

lnevo · Post by **lnevo** » Fri Jan 03, 2014 3:11 pm

No the primary probe.

ReEfnWrX · Post by **ReEfnWrX** » Fri Jan 03, 2014 7:35 pm

You may want to look into galvanic isolation and see if you think it will help, if so get the pH expansion... It is on my list to buy soon... Everyone I know with an Apex does not get any voltage interference with their pH probes because the Apex comes standard with Galvanic isolation.

saf1 · Post by **saf1** » Thu Jan 09, 2014 12:04 pm

ReEfnWrX wrote:You may want to look into galvanic isolation and see if you think it will help, if so get the pH expansion... It is on my list to buy soon... Everyone I know with an Apex does not get any voltage interference with their pH probes because the Apex comes standard with Galvanic isolation.

Not sure I understand this so wanted to ask a question. I have the standard Reef Angel Plus (extra memory I guess, right?) and it the pH unit built in. Ironically reading the boards today I came across this and while I've not measured for stray voltage (I'll check tonight) I am seeing random spikes in my pH reading on the ReefAngel Client (v3.0). I'll see a pretty regular graph and then all of a sudden it will dive down to 6 or so then right back up to 8 or whatever it is at.

So in this case and having the pH on the controller itself how do you or do you need to run with Galvanic isolation? Or am I mixing something up here altogether (which is probably the case).

rimai · Post by **rimai** » Thu Jan 09, 2014 12:34 pm

The dips in the client is related to the client I think.

ReEfnWrX · Post by **ReEfnWrX** » Thu Jan 09, 2014 12:46 pm

saf1 wrote:Not sure I understand this so wanted to ask a question. I have the standard Reef Angel Plus (extra memory I guess, right?) and it the pH unit built in. Ironically reading the boards today I came across this and while I've not measured for stray voltage (I'll check tonight) I am seeing random spikes in my pH reading on the ReefAngel Client (v3.0). I'll see a pretty regular graph and then all of a sudden it will dive down to 6 or so then right back up to 8 or whatever it is at.

So in this case and having the pH on the controller itself how do you or do you need to run with Galvanic isolation? Or am I mixing something up here altogether (which is probably the case).

Roberto can correct me if I am wrong. But if I understood him correctly, there is Galvanic isolation in the pH expansion unit but not in the base pH port on the RA unit.

It would be interesting if someone with a pH expansion unit who thinks they may have or used to have stray voltage would test their pH in the tank and in a cup of water with the base pH port and do the same test using their pH Expansion port.

I do plan to buy a pH expansion very soon as galvanic isolation is supposed to prevent the affects of stray voltage on Probes readings.

rimai · Post by **rimai** » Thu Jan 09, 2014 1:05 pm

Keep in mind that the stray voltage is not coming from the probe.
It's originated in one of your equipment that is plugged into RA. Usually powerheads, heaters, pumps, LED drivers or even a PC computer.
The probe is just providing a point of differential voltage and completing the circuit.
If you have any other point of differential voltage dipped into the water, you would still get the stray voltage, regardless of the probe being in the water or not.
So, you are only treating the symptom by isolating the probe. You are not treating the cause.
It's the same analogy when you dump chemicals or shut the lights off to kill algae in your tank. You are simply treating the symptom.
The best is to identify which equipment is the problematic one and remove/replace it.

ReEfnWrX · Post by **ReEfnWrX** » Thu Jan 09, 2014 4:23 pm

This is true and I agree, however... Majority of times when stray voltage is a factor it is coming from a main pump which typically cost a decent amount of money.. Every return pump I've had has caused stray voltage after a couple of months and I do not think it is worth it to replace a $100+ pump every couple months.

From my research, the only time stray voltage is to be of concern is in two situations.

1. You use probes that do not have galvanic isolation and therefor the reading will be affected slightly.

2. If your tank is not grounded every time you touch the tank and feel the current or a shock... You are not the only one feeling it, everything that is living in your tank feels it as well, because you are completing the circuit and allowing the current to leave the tank water.... Which is why it is very important to at least get a grounding probe so you are not affecting your livestock every time you touch the tank water.

bmhair03 · Post by **bmhair03** » Mon Mar 03, 2014 4:16 pm

Roberto what is the meanwell connection if any?. My ph reading drops 2 points when my lights come on. Going to recal but still think it's linked to lights.

rimai · Post by **rimai** » Mon Mar 03, 2014 4:17 pm

You are not the first one to complain about this and their drivers.
Did you replace any drivers recently or still original drivers?

bmhair03 · Post by **bmhair03** » Tue Mar 04, 2014 8:31 pm

I believe I switched one out. Others orig. Don't remember which one.

rimai · Post by **rimai** » Tue Mar 04, 2014 11:09 pm

I think they changed something along the way.
Do you know which one is the new one?
The new dimming modules have optical isolation to avoid this problem.

bmhair03 · Post by **bmhair03** » Wed Mar 05, 2014 6:39 pm

Yes I figured it out. But what would be the fix if any.

rimai · Post by **rimai** » Wed Mar 05, 2014 7:39 pm

Optical isolation, which the new dimming modules have.

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