Shocked!

[rsarvis]

Thought I'd share this story, just to remind people to be careful. We have a lot of electricity going through devices submerged in saltwater....

 

I got an electrical shock today while sticking my hand in the back of the tank. I'm still not sure why it happened, but I was reaching over a corner of the light fixture (near where the cords attach, in fact) and into the tank to try to brush off some junk on a powerhead when I felt a zap in my arm.

 

Scared the bejesus out of me, though all major bodily and brain functions appear to be in working order.

 

I turned off the entire power strip that controls the lights and other things in that corner of the tank. I actually then got another much smaller shock not too long after that, while reaching for another powerhead, which I thought was weird, b/c the second shock also felt like it came right where my upper arm was touching the light fixture, but the light fixture was off. What might that have been? Does that maybe have anything to do with "stray voltage" that I've heard mentioned?

 

It makes me realize that I'd probably been feeling very small shocks previously where my arm touched a corner of the light fixture; I'd feel a little p#*!k-like feeling, but then figured maybe an arm-hair got caught. But I doubt that's what was actually happening.

 

Well, anyway, I've decided that anytime I do anything other than minor repositioning in the front of the tank, I'm going to turn most everything off. I don't know enough to know when I'm doing something remotely dangerous, so I'll just be overly careful.

[xCGx]

Did you have a GFI and grounding probe? I have both and have had the grounding probe trip the GFI while my hands were in the tank.

[rsarvis]

One of the outlets does, the other doesn't. I thought about installing one about 9 months ago, when I was first starting out, but ended up not doing it. Probably should do that, huh? Will suck, though, if it flips when I'm not home for a long stretch of time.

 

Did you have a GFI and grounding probe? I have both and have had the grounding probe trip the GFI while my hands were in the tank.

[xCGx]

I've never had mine trip when I wasn't home. Some people have the main pump on a seperate outlet and their powerheads,etc. on anothers so that if one trips the other is working. Also, make sure you have your power pords have the drip in them so the water goes below the outlet.''

 

One has a grounding probe or one has a GFI?

Edited January 20, 2008 by xCGx

[fab]

Use a voltmeter. They are cheap at RadioShack.

 

Put the red probe in the tank so its metal tip is submerged.

Put the other, black, probe on a ground wire; not the grounding wire for your aquarium. Use something connected to the ground lug of your electrical circuit.

Read the voltage. Switch the meter between DC and AC readouts.

 

That will tell you if you have a so-called 'stray voltage'f leaking into your tank.

 

If you see much voltage you can track it down by turning off everything and turning your devices on one at a time to see which one produces a significant voltage. Then you can look into how to fix or replace that device.

 

You can do the same thing with your electrical devices. Instead of putting the red probe in the water, touch it to difference devices that are not submerged. Read the voltage, looking for anything not trivially small. Example: put the red probe on the hanging wires of your light fixture. If you see a large voltage reading it is probably not well grounded.

 

There is no need to guess here. Voltmeters are cheap and easy to use.

 

fab

Edited January 20, 2008 by fab

[YBeNormal]

I second what fab said and strongly suggest that anytime you feel a shock when working on your tank--you need to track down the cause! IME, stray voltage sufficient to cause a tingle (or worse) is usually caused by a defective pump or powerhead. The second most common cause is corrosion within the light fixture.

[dschflier]

Is your lighting a DIY setup or a ready made hood? I ask because if somewhere in your wiring your polarity is reversed, meaning your load and your neutral are reversed you can get a shock even with the lights off.

 

My understanding is, if the wires are reversed then the power goes all the way up through the socket and back to the actual switch. When the switch is off the light will still be off because the current cant flow past the switch but you can still get shocked. If it is done correctly when the switch is off the power does not go to the appliance at all.

 

If someone on this forum is an electritian or knows more correct me if I am wrong. I also think if you had a GFCI that it would constantly pop in this condition.

[gmubeach]

Check for nicked cables I have had 2 nicked cables and It sucks I got shocked very badly just a reminder to ground your tanks:)

[Origami]

I turned off the entire power strip that controls the lights and other things in that corner of the tank. I actually then got another much smaller shock not too long after that, while reaching for another powerhead, which I thought was weird, b/c the second shock also felt like it came right where my upper arm was touching the light fixture, but the light fixture was off. What might that have been? Does that maybe have anything to do with "stray voltage" that I've heard mentioned?

 

I'm guessing that the case of your light fixture is grounded and that you were taking stray voltage from something that was still "live" in the tank (not a good thing!), having it pass through you and into the case ground (thereby completing the circuit). This can be very, very dangerous. It only takes a few 10's of milliamps across the right area of your heart to put your heart into fibrillation. Is your equipment on a GFCI? Do you have a glass heater that might be cracked?

 

A grounding probe is a good idea. But you need to track down where the charge is coming from. The multimeter idea is a good one. Put one line to ground (the third, round pin on a socket) and one into the water. Set the multimeter to AC volts since that's the likely source. Look for a reading. Then take everything down and bring your system up one item at a time and watch to see which thing is causing the problem.

 

Good luck.

Edited January 20, 2008 by Origami2547

[rsarvis]

Thank you all for your comments; it's all very educational. What YBeNormal said --about stray voltage being caused by a defective pump-- makes me think it was probably the powerhead that I found wasn't working. I'll take all your guys' advice and try to make my set-up safer.

 

I second what fab said and strongly suggest that anytime you feel a shock when working on your tank--you need to track down the cause! IME, stray voltage sufficient to cause a tingle (or worse) is usually caused by a defective pump or powerhead. The second most common cause is corrosion within the light fixture.

 

 

One has a grounding probe or one has a GFI?

 

One has a GFI. I actually hadn't heard/read about grounding one's tank. I'll definitely do that. Have a good link to read?

[txaggies07]

I had a stray current caused by a heater that stopped working. I got a H-E-double hocky sticks of a shock. Get a grounding probe.

 

Ground probe

Edited January 20, 2008 by txaggies07