Acceptable voltage level in water?

X

xxkenny90xx

New member
So I've been working on my tank upgrade for a week or so, and the other day I was moving rocks around and my elbow bumped my light fixture and I got a pretty nice shock. Instantly I blamed my light, but once I thought about it the light is just the ground, so I took my voltmeter to the water and got readings from 0.11 to 0.29v. What do you guys think of that? Seems low for the shock it gave me. Should I be replacing equipment over this voltage or is it low enough to not worry about? Also, I've researched ground probes already and decided against one.
 
Just a suggestion, check your light fixture to make sure the outside frame is not being energized by a nicked or frayed wire inside it. Use your meter to check. I presume your equipment is all plugged into a GFCI or a dedicated GFCI circuit?
 
Yeah you want to change the power strip to one that has GFCI protection. Tripp-Lite makes one that has it on Amazon. Or swap your outlet with a GFCI one..hope this helps.
 
One thing to note about measuring voltage; putting a V.O.M. probe in just about any tank and the other to a ground will register some amount of voltage. That's of little concern, since virtually no current would flow if the tank water were grounded. OTOH, if you register 120V, you've a serious issue that needs to be addressed immediately.

On the GFCI subject, be extremely cautious about doing this. A nuisance trip is no big deal if it's your coffee maker. A nuisance trip on a circuit that's running your entire reef tank equals "bait bucket setting in the sun" if not caught quickly. I personally wouldn't recommend it unless you have one or more of your wavemaker pumps on a backup battery.
 
The following is from 10+ ears ago but it gives you some ideas of stray voltage levels

Tank #1 - 200 gallon, wet dry filter system, Mag. pump for the skimmer, Pan World 100PXX for the return. On lighting, 2 – 250 watt MH, 4 – 54w T5HO, 1 – 160 watt VHO.
Stray voltage – 14.5 volts and yes no tingle, even when I was barefooted and wet floor. Turn off the metal halides and it drops to 8.5 volts, turn off the rest of the lighting and it drops below 2 volts. For a clarification my hood is brand new, with no salt creep or moisture and the lamps are a minimum of 8” above the water.

Tank #2 – 155 gallon, wet dry filter system, Mag. pump for the skimmer, Pan World 50PXX for the return. On lighting, 2 – 250 watt MH mounted in a 5’ Orbit light
Stray voltage – less than .5 volts with everything running. Clarification light is metal and grounded and the tank has glass tops.

Tank #3 – 29 gallon with an eclipse three filter system. The lighting consists of a 96 watt Quad PC with a 2 ½” fan from Radio Shack for cooling.
Stray voltage – 9 volts and once again no tingle. I grounded the reflector and the voltage only dropped a volt. Turn off light and voltage is below .5 volts. For clarification once again no moisture everything is dry, lamps is mounted only 3” above the water.
Your return pump should be on its own GFCI protection, do not share protection with heater and powerheads
 
ALL water will have an electrical current in it, its the metals in the water that causes this and there is no way to completetly avoid it.. For example cars the radiator fluid is specially made to prevent not only corrosion and to keep it from freezing. If you dont change the fluid enough it actually builds up a electrical current in the fluid, which can eat up the metals in the radiator, and engine block. To fix this you need to do a 100% coolant change, but you can also add a sacrifical anode to take the electrical current build up and save the other metals in your car.

There is something wrong with your light fixture if you got shocked like this. The fixture should be properly grounded if it isnt it will shock you. I had this issue with a T5 fixture, when i used some tin foil to replace the worn out reflector.. the tin foil i had wrapped around the metal frame of the fixture and this actually pulled a small current from the fixture and cause me to shock myself slightly not alot but enough to noticed this. So something on your fixture isnt grounded.

Stay away from belkin power strips they are poorly put together and have been known to cause fires. Get a Tripplite power bar, or APC power strip. Tripp-lite is one of the best you can buy. I use them for my computers and they last decades. I wouldnt put my $4500 computer i just built on anything else.

This is the power strip i would use https://www.amazon.com/Tripp-Lite-O...lite+gfci&qid=1553516831&s=electronics&sr=1-1
 
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Assuming you have a multimeter capable of resistance/continuity measurements simply check the resistance from the metal enclosure of your light to ground. If low resistance (continuity beep) then it was simply the path to ground and not the source of the potential.

Most meters will easily register up to a few volts just walking around your house holding the probes in the air.. Get close to a fluorescent light and watch it go up.. Get close to a motor and watch it go up..

I wouldn't be concerned until I say something near 1/3rd line voltage. Above that an I would start some investigating..

I also will ONLY have a system in which ALL submerged direct line powered equipment is protected by GFCI (RCD in other countries) protection.

And yes.. TO echo the comments from dkeller above its a VERY good idea to split the equipment over multiple GFCI circuits so that in the event of a nuisance trip on one your whole tank isn't sitting there without any water movement,etc...

NEVER install a ground probe unless that system also features GFCI protection..
Current cannot flow unless there is a path to ground or a voltage potential..
Installing a ground probe provides a path to ground that wouldn't normally exist.. That in itself can cause more problems than its solving and mask issues.

A ground probes only real purpose is to cause the GFCI protection to trip the instant a fault occurs.. Without one the GFCI won't trip until you become the path for ground.
The "con" of a ground probe is that if you aren't home or aren't alerted to a GFCI tripping because of a fault/ground probe your system could be sitting there without water movement,etc... (but multiple GFCIs help there too)

FWIW.. I run 2 GFCI circuits and do NOT run a GFCI probe on my systems..
 
mcgyvr said:
Assuming you have a multimeter capable of resistance/continuity measurements simply check the resistance from the metal enclosure of your light to ground. If low resistance (continuity beep) then it was simply the path to ground and not the source of the potential.

Most meters will easily register up to a few volts just walking around your house holding the probes in the air.. Get close to a fluorescent light and watch it go up.. Get close to a motor and watch it go up..

I wouldn't be concerned until I say something near 1/3rd line voltage. Above that an I would start some investigating..

I also will ONLY have a system in which ALL submerged direct line powered equipment is protected by GFCI (RCD in other countries) protection.

And yes.. TO echo the comments from dkeller above its a VERY good idea to split the equipment over multiple GFCI circuits so that in the event of a nuisance trip on one your whole tank isn't sitting there without any water movement,etc...

NEVER install a ground probe unless that system also features GFCI protection..
Current cannot flow unless there is a path to ground or a voltage potential..
Installing a ground probe provides a path to ground that wouldn't normally exist.. That in itself can cause more problems than its solving and mask issues.

A ground probes only real purpose is to cause the GFCI protection to trip the instant a fault occurs.. Without one the GFCI won't trip until you become the path for ground.
The "con" of a ground probe is that if you aren't home or aren't alerted to a GFCI tripping because of a fault/ground probe your system could be sitting there without water movement,etc... (but multiple GFCIs help there too)

FWIW.. I run 2 GFCI circuits and do NOT run a GFCI probe on my systems..
Click to expand...


^^^This^^^

I have 2 x 20A circuits running to my to the wall behind my DT. Neither is GFCI, however I also 8 individual GFCI outlets installed inside the stand so that there are multiple redundancies for all equipment. It is set up so that each 20A circuit feeds 4 of the GFCI outlets. I've had one or two trip at the same time, but have never had all of them trip at the same time.

Back in the day (pre GFCI) I had a maxijet power head stop working. I unplugged it, took it to the kitchen to clean, and then put it in a bowl of water to test. Nothing happened, so I reached in to give it a shake. I came to about 15' away on the other side of the room. I wondered around the house for about an hour telling myself "Yeah - I'm ok".

I don't play around with electricity anymore. I may have gone a bit overboard with the GFCI on this build, but I figure that was my one and only wake-up call from the Electric Gods.

And now, if a powerhead doesn't start on it's own after a good cleaning, it goes in the trash. Equipment is cheap. Funerals are not.
 
Thanks for all of the advice guys. From what I'm hearing, my waters voltage may not be an issue, but I need to switch to gfci anyways to be safe. I assume only my submerged equipment needs to be switched to gfci outlets, not things like light, temp probe, ato, ect? I will definitely take a look at my light fixture (reef breeders photon 48 led). It's currently having an issue where 24 of the LEDs aren't working so I pulled it all apart, maybe I missed a ground when I put it back together. I'll let you know what I find!
 
Correct only submerged line powered equipment needs to be GFCI protected..

One could make a case that if your light has a direct line plug and it would fall into the water that having it on a GFCI also wouldn't be a bad idea ;)

No need to put low voltage DC stuff like many "wavemakers" or temp probes/ato,.etc... on it..
 
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