View Full Version : How much stray voltage is too much

03/02/2017, 10:14 AM
Trying to narrow down cause for bleaching corals- birdsnest, candy canes and Hollywood stunner. I think it's too much light from my kessils but... Checked for stray voltage by grounding the negative lead of my voltmeter to the ground plug in an open outlet of my Apex, and dropping positive lead in my sump. Reading shows 2 volts (will flash 3). I turned off all outlets one by one to see which item was leaking voltage. The Hydor koralia pumps in my DT, the one in my sump and the Eheim return pump each dropped about 1 volt when unplugged. It took unplugging all three devices in order to show 0 volts. Is 2-3 volts a lot or not? I'm guessing its the magnetic fields in the motors causing the voltage leak? I don't know if thats something that can be fixed. Please advise

03/02/2017, 11:11 AM
This is why I went to vortech pumps in the first place. One by one each koralia pump started to cause this. At one point enough to shock the heck out of me. Knocked me back.

May want to minimize cords in the water if you can. My current setup doesn't have a single cord submerged except for 2 or 3in from the skimmer pump.

03/02/2017, 12:33 PM
2-3 volts is good, my system usually runs 12ish. The problem as you state is that when each piece of equipment adds 1-2v, you can't eliminate the voltage by replacing the equipment. I just check it a few times a year and if there is one piece of equipment contributing most of the voltage, try to replace that one item. Also make sure you are checking when all the equipment is powered on (i.e. heater is actively heating, all powerheads on, etc).

I too have found koralias to be the source of most of my stray voltage.

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03/02/2017, 05:21 PM
What you are reading is TOTALLY normal and NOT an issue at all.
And NOT an indication at all that a pump,etc.. is failing or faulty by any means...

Walk around your house and read the meter.. It will always show some voltage readings.. Move it closer to a fluorescent light... oohhh... more voltage..
Move it near a motor....ohhh...voltage..
High impedance meters will always show "something"..

I recommend it be ignored unless its 30-50% or greater of line voltage (AC supply).. So in the US I wouldn't worry until 50+ volts are measured..

And of course..
Public Service Announcement
All AC line powered submerged equipment should be protected via a GFCI powerstrip/outlet/breaker or similar.. A normal powerstrip/surge protector does not NOT GFCI protection.. A cheap $20 device could save your life..

03/02/2017, 06:21 PM
It's not really a voltage leak, right? If you ground an ohmmeter, and place the positive lead near an AC motor, there is an oscillating electromagnetic field there, and a current is induced in the lead, which is acting as an antenna... so this is not indicative of something being wrong with a pump, like a crack or something inside, allowing saltwater in. There really is no leak, just an electromagnetic field due to the operation of an AC motor, and an ohmmeter will show a voltage if placed in this field while other lead is grounded...

Sorta like radio.... an alternating electromagnetic field induces a current in your antenna wire, which is fed and amplified in your radio.

03/03/2017, 04:59 PM
It's not really a voltage leak, right?