View Full Version : Have you checked for stray voltage lately?

10-21-2014, 07:22 PM
Thought I'd share my my experience from a couple nights ago. Have never noticed any problems with the tank and never thought to check with a voltmeter.

Until I went to move some rocks around in a tank and when I put my hand in the water got zapped, turns out I had a small cut on a finger! Went outside and grabbed the voltmeter from the shed and a new Rid-volt grounding probe I had bought for another tank. Plugged the grounding probe into the power bar. First I tested from the grounding probe to the tank water and got a fluctuating reading from -.20 volts up to .30. Then put the grounding probe into the tank and tested from a ground hole in a socket to the tank water and got the same random readings! Then tested with both leads in the tank water and still got low voltage readings. I thought the grounding probe would solve it but noooo.... So where's the stray voltage coming from? I unplugged the heater, nope. The koralia power head, nope. The skimmer, nope. The aquaclear filter, nope. No single item in the tank was the cause of voltage!? So I unplugged all 4 items at the same time. STILL stray voltage! Same random readings.
I thought WTf! My GF said what about the lights? Hmmm, well they aren't touching the tank water but what the heck. Unplugged the lights and GONE! I'm using a 24" coralife T5H0 fixture, it has plastic legs that straddle the tank and sit on to of the plastic tank trim, so how does the voltage get into the tank water? I touched the legs and inspected the lights, there was salt creep all over it!
I plugged the light back in and touched the aluminum housing of the light, zap! Ah Ha!
I then looked on the floor at the plug for the lights. I had it plugged into a manual timer, and in order to do so I had to use a 3 prong to 2 prong adaptor, DOH! Kinda stupid condsidering everything else is plugged into a digital power bar. I had a power outage 6 months ago and instead of re-programming the power bar I got lazy and just used a manual timer. So I plugged the light into a proper 3 prong plug, tested for voltage again and it was gone!

Anyway, some valuable lessons learned. Test for stray voltage. If an electrical component has a 3 prong plug don't use a 2 prong adaptor (or break the ground prong off) it's probably there for a reason. Just because there's a grounding probe in the tank doesn't mean there isn't stray voltage. Salt creep really can be creepy! Use a GFCI and ground probe to be safe.

Safe reefing!

10-21-2014, 09:29 PM
Good idea to point that out. I actually had the exact same issue with my lights. It was bad enough that if my arm was in the tank and my elbow touched my light I got shocked. Didn't realize it was the timers. They only were made for 2 prongs so I just drilled out a 3 hole for the ground. Didn't know what it was until I got my apex and no longer used the manual timers.

10-22-2014, 03:51 PM
A few months ago the no name feed pump for our reactors wasn't preforming very well so I took it out of service & ran it in a pail of vinegar hoping to clean it. It definitely put enough voltage into the pail of vinegar to get my attention, we now check for stray voltage every water change. Great Safety topic, we are now looking for a rid-volt grounding prob, thanks for bringing it up!