Stray Voltage

[scherzo]

Hi all,

I had thought my skimmer was creating some stray voltage but it was an MJ -1200 that I used in my sump.

The Maxi-Jet showed 32V when it was plugged in.

However - With everything else it shows about 3.4 - 4.0 volts.
Is this acceptable? Should it be closer to zero? What do your tanks read?

I've googled this to death and answers seem to be all over the place. Just want to see what things are like locally.

[mike31154]

Answers will be all over the place due to the variety of equipment we all use. Certain components will induce more voltage than others. It will even vary with the same brand of component due to manufacturing quality (or lack thereof), age of equipment & where/how you have it hooked up.

For example, most fluorescent lights & many MH ballasts are capable of inducing a voltage potential into your water without even being in direct contact. How much will depend largely on the exact type of equipment, how close to the water it is & many other variables. It's next to impossible to have 0 volts potential in your water. Salt water itself is a form of 'electrolyte' and simply having two dissimilar metal objects in the water will turn your tank into a battery capable of producing it's own voltage potential. If the two dissimilar metal objects are close enough together, current will flow between them provided there's a path to ground or the circuit is completed in some other manner. Same idea with any voltage potential in your tank. It's only a 'potential' & will have no effect on anything until a path or complete circuit is provided. This path could be you, if you're standing in a puddle or are wet & in contact with an external ground when you reach your hand into the water. You can also be zapped by touching your light fixture with one body part while your hand or other body part is in the tank water. This is why GFCI devices are pretty much mandatory for anything electrical close to or in your tank.

There are a few things you can do to minimize the effect of electrical gizmos on your water.

Don't fully submerge your heater, control head, cord & all. The manufacturer may claim it's fully submersible, but are you willing to take their word for it with your life, your family's life or your home?

Keep the number of power bars to a minimum, ensure you have drip loops on all the cords & keep the outlets as far away from water as practicable. Ideally you will have a wall receptacle for each component you use on your tank and each one will be GFCI protected. If you read up on codes, power bars & extension cords are only supposed to be used 'temporarily' with moveable equipment. Most of the stuff on our tanks is hooked up 24/7/365, so hardly 'temporary'.

Use external return pumps instead of submersible pumps. Change your AC return pump for a DC model. Same goes for power heads. If you can afford it, go with low voltage DC powerheads like VorTech or the low voltage Jebaos now available. The fewer cords & motors submersed in your tank, the safer & less prone to induced voltage. AC voltage due to the constantly expanding & collapsing magnetic field, will always induce more voltage into surrounding material than DC voltage. And since household AC is up there around 120 volts whereas most DC components available are 24 volts & less, the safer choice is obvious.

Ditch your T5HO flourescents & MH lights for LEDs. There remains much controversy over what grows the best SPS & what looks more appealing to a given hobbyist's eyes, but if safety is the driving factor, low voltage LEDs are the way to go. Fluorescent & MH ballasts produce voltage potentials of up to 1000 volts or more, depending on the fixture. That's a scary number around salt water.

3 or 4 volts won't hurt a thing.

I personally don't use a grounding probe. To me it's a waste of time/money & is a sure fire way to provide a path for current to flow, which is the last thing I want to do. If you find a voltage in your system in the 30 range & over, starting looking at your gear & fix whatever's causing that amount of voltage to be present. You pretty much did the right thing in identifying your maxijet as the culprit.

[Magickiwi]

I use a grounding probe. Partly to eliminate stray voltage in the tank but also as a safety item for me. If I'm monkeying with my arm in the tank up to my armpit and I accidentally knock the skimmer, or a light fixture, whatever into the tank I'd rather blow a breaker than fry myself.

To me it's like playing with toasters while you're in the bath.

[frizzo1983]

+1

[scherzo]

I'm assuming a grounding probe would have allowed the GFCI to trip. The Maxijet is only a 2 prong device so maybe a ground probe would have helped here.

My heaters are out of the water and I run an external pump. My DT has 2 vortechs so there is no electricity there. Just my skimmer pump and any power heads use in my fuge. (Like the Maxijet )

[mike31154]

A grounding probe without a GFCI device is inadequate protection. There are many fault scenarios & the best bet is a GFCI with respect to safety. By the time a 15 amp circuit breaker blows, if any of your body parts are in the tank, you will be a hurting buckaroo, if not dead. Circuit breakers are to keep your house from burning down, not for personal protection from getting shocked.

http://angel-strike.com/aquarium/GroundingProbes.html

http://angel-strike.com/aquarium/GFI&TechnicalDetails.html

[gregzz4]

Circuit breakers are to keep your house from burning down, not for personal protection from getting shocked
+1
Don't use a probe without a GFCI :surprise:

[Magickiwi]

A grounding probe without a GFCI device is inadequate protection. There are many fault scenarios & the best bet is a GFCI with respect to safety. By the time a 15 amp circuit breaker blows, if any of your body parts are in the tank, you will be a hurting buckaroo, if not dead. Circuit breakers are to keep your house from burning down, not for personal protection from getting shocked.

http://angel-strike.com/aquarium/GroundingProbes.html

http://angel-strike.com/aquarium/GFI&TechnicalDetails.html

I am using a GFCI power bar but the probe on its own would provide enough protection from stray voltage. As soon as the current started flowing into the tank it would go to ground as the path of least resistance. That's how a probe protects you, not by triggering a breaker.

[gregzz4]

I'd like to hear an electrician's take on this as I agree with Mike
Using a ground probe without a GFCI is not good

If you do have current in your tank without a ground probe, you will get a shock if you personally create a path to complete the circuit. But during the time you're not doing that, your critters are not bothered by the electricity if isn't a complete circuit

If you use a probe and no GFCI, any stray current will now become a completed circuit and will affect your critters as the water is now energized
And, if the current suddenly becomes much greater and you stick your hand in the water, you'll get a painful or potentially heart-stopping jolt long before the breaker trips

I read a long time ago to only use a probe if you use a GFCI, and I stick to it
And a probe is not a solution to a problem
Repairing or replacing the faulty equipment is the only way to go

[Magma]

I'd like to hear an electrician's take on this as I agree with Mike

And a probe is not a solution to a problem
Repairing or replacing the faulty equipment is the only way to go


This right here ^ a probe is not a solution! Its "hiding" the problem. Its like you have a leaking pipe, instead of fixing it you just put a few wraps of duct tape over it, sure it works for a while but when it breaks again its a worse problem then before.

Fix or replace the equipment save yourself problems later its so simple.

If you do use them make sure EVERYTHING is plugged into a GFCI Protected Plug.

Found a nice little list which I agree with from what I have personally seen by working as an Electrician. I have seen many of these problems occur when using GFCI's for various uses.


Pros
Any current from shorted equipment in the tank will be shorted to ground saving you from getting shocked.

If there is some condition that would allow current flow in the tank when something shorts, it would also be alleviated using a grounding probe.

Depending on specific grounding probe setup
If a probe is placed in the correct location (such as a sump with pumps), they can short induced voltage to ground without tripping the GFCI. However, if there is anything between the voltage source and the probe, it will be shocked. Also, if you have large pumps, it's possible they would induce enough voltage to trip the GFCI without there actually being a short.

Cons
You get a short and instead of nothing happening, everything turns off! If you're on vacation or even away for the weekend, tank is toast, even though there may be no danger to the livestock.

If you have a pump that induces a lot of voltage in the tank, you will get current flow between the pump and the probe. You don't want this taking place in the DT. You also don't want a pump tripping your GFCI for no reason.

If you do develop a short with a grounding probe, you can create a staggering amount of current because the water has very little resistance. Another reason why a probe in a DT is a bad idea.

On my personal tank I use drip loops on all cords and have my lights, heaters, return pump and wavemakers all on different circuits. They are also NOT GFCI protected. What I did was wire in a bank of plugs onto my stand up high, and each plug has its own cabtire which runs back to a wall outlet. Never had an issue with them, I also test for stray voltage every few months just to make sure all my gear is ok. I would rather do this quick test than run the risk of finding a burnt out a motor or heater after being away from the tank all day from work.

[scherzo]

Lots of good thoughts here.

I did find the faulty piece of equipment t (my Maxijet 1200) so good news there.

I do have a GFCI and all of my power is mounted high so water can't travel up the cord. It is an in wall tank with a utility room behind it so I have a tonne of space to mount the power up high.

What I had wished was that as soon as I dropped the Maxijet into the water (just after cleaning) and as soon as I plugged it in, something should have tripped. It did not. I just felt the voltage once I put my hand in the tank. Then tested and saw 32 volts.

The solution of finding the problem and fixing it might be too late... If you get electrocuted first.

I have a Neptune apex. They should make a module to detect stray voltage. That way, you'll know before you stick your hand in the tank.

[gregzz4]

If you have time to read The Bean's info on it (http://www.beananimal.com/articles/electricity-for-the-reefer.aspx), it may help you understand why your GFCI didn't trip
Don't let your eyes glaze over; just scroll down about half-way to get the goods

Voltage 'leaking' can cause tricky issues
I'm no electrician, but you can get power going from 'here to there' and the GFCI won't trip

Forgive my lack of description and read the link :wink:

[mike31154]

I guess what it comes down to is that there is no 'absolute' solution here. There are so many different fault scenarios when it comes to electrical gear that it's difficult if not impossible to cover them all. Some are more likely to happen than others, but the possibility is there. Both GFCIs & Grounding Probes themselves can fail and as shown, a GFCI does not trip for some fault scenarios & it may also nuisance trip due to the tiny amount of current leakage that can set it off.

Each of us needs to do their own 'risk analysis' based on the amount & type of electrical gear we have hooked up to our systems. How in depth this risk analysis is, will depend on your own knowledge & information you can gather on your equipment. In my career in as an Air Force Instrument Electrical Tech, before any modification could be installed on an aircraft system, one of the things that had to be done was a 'risk analysis'. Believe me, when an urgent mod is required, everyone's in a hurry, but there are no shortcuts here. Of course our systems are somewhat less complex & we're not all electricians, so the best we can do is use the safety devices available (GFCI, Ground Probes if you wish, power bars with circuit breakers, fuses, drip loops, etc. etc.) and perform regular checks on our equipment. Keep a special eye on anything that's actually submerged with a cord & motor or heating element. Epoxy is a wonderful thing & does a great job of water proofing motors inside casings, but the power cord has to go through that epoxy blob somewhere and with age, this interface will deteriorate in salt water & eventually cause problems.

Perhaps the 'absolute' solution is to run our systems with no electrics. Sun for lighting & hamsters in a squirrel cage running a mechanical pump to move water.