worst night of my life

[TRIX]

Most salt water stores carry them. JL aquatics http://www.jlaquatics.com/phpstore/s...oduct_ID=mc-gp .

[deep_six]

I feel for you!
Believe it or not I had a similar experiance a couple weeks ago. I put a second heater into my sump to better regulate temp. and not even an hour later it completely exploded. The side of my sump was gone and there was water all over my office entrance. Luckily there was not a lot of damage to the main tank and most of the fish and corals survived. Although my toadstool leather did close up for about a week after.
Everything seems back to normal now.

[Dale]

Hi Deep six! Welcome to the forum.

It's probably worth noting the difference between surge protectors and GFCI's.

A surge protector protects delicate electronics from surges originating from the grid (lightning strikes, transformer accidents).
A GFCI prevents an electrical component from drawing too much power from the grid (malfunctioning heaters, knocked in lights).
A surge protector won't prevent electrification of the water but a GFCI will. I don't know if it would have helped in this case but a GFCI's reaction time is in milliseconds. A grounding probe is useful in removing random stray voltage but it would not help in a large way in this situation. The grounding probe would try to draw off the unrestricted voltage from the heater but it could not turn the heater off. Only a GFCI or a blown fuse/breaker would do that.

As you can tell I am a big fan of GFCI's and I try to install them in every system I set up. I have already had a client that had her arm elbow deep in the tank when she knocked the actinics in. She received a small shock but the GFCI worked and tripped off the power supply.

[midgetwaiter]

Originally Posted by Dale

A GFCI prevents an electrical component from drawing too much power from the grid (malfunctioning heaters, knocked in lights).

This is technically incorrect. What A GFCI does is detect that there is current leaving on the hot wire that is not being returned on the neutral. ie it is going to ground through you, this is when it trips. In Steve's situation the current didn't have a path to ground, the GFCI may not have stopped anything

A ground probe could also save you in the "knock the lights in" situation. If there is a device leaking current into the water the ground probe gives it a path to ground. The "save you" function of a ground probe is pretty simple, that current wants to go to ground and hopefully the probe provides a better way to do that than you do.

Talking about a ground probe "removing" stray voltage is also flawed. The assumption is that having this stray current in the tank is bad for the inhabitants but there isn't a lot of proof for it. A leaky device is giving you potential current but it's not until you get a path to ground, ie your probe, that you have current flowing through the water. Think about a bird on a power line. Touching one line, no problem but touch another line or the ground at the same time and you have a big problem. Is potential current or a completed circuit worse for fish and inverts? I don't think there is a definitive answer.

The thing that could have saved Steve's critters is both a GFCI and a ground probe. When the heater broke the current would have gone to ground rather than returning on the neutral and it should trip. This probably would have worked but I think you'd have to look far and wide to find many people that use both these devices.

[Dale]

Originally Posted by midgetwaiter

This is technically incorrect. What A GFCI does is detect that there is current leaving on the hot wire that is not being returned on the neutral. ie it is going to ground through you, this is when it trips. In Steve's situation the current didn't have a path to ground, the GFCI may not have stopped anything


A ground probe could also save you in the "knock the lights in" situation. If there is a device leaking current into the water the ground probe gives it a path to ground. The "save you" function of a ground probe is pretty simple, that current wants to go to ground and hopefully the probe provides a better way to do that than you do.


Talking about a ground probe "removing" stray voltage is also flawed. The assumption is that having this stray current in the tank is bad for the inhabitants but there isn't a lot of proof for it. A leaky device is giving you potential current but it's not until you get a path to ground, ie your probe, that you have current flowing through the water. Think about a bird on a power line. Touching one line, no problem but touch another line or the ground at the same time and you have a big problem. Is potential current or a completed circuit worse for fish and inverts? I don't think there is a definitive answer.


The thing that could have saved Steve's critters is both a GFCI and a ground probe. When the heater broke the current would have gone to ground rather than returning on the neutral and it should trip. This probably would have worked but I think you'd have to look far and wide to find many people that use both these devices.

Yes, to be specific I would have prefered to say that the GFCI trips when an appliance uses electricity in a way not normally anticipated (my bad). I was being somewhat general on the point as I was trying to illustrate the difference between a surge protector and a GFCI. Some people assume a surge protector on a powerbar will protect them which, of course, is false. I also made note that I didn't know if it would have helped in that situation. My main intention was to help others protect themselves while working near saltwater.

It's interesting that this type of discussion doesn't come up more considering the amount of electrical appliances used in close proximity to an excellent conductor like saltwater. Like plumbing a tank I always try to plan for the worse case scenario.

I'm a little worried about your contention that a grounding probe is as protective as a GFCI though. If you want to bet your life using a grounding probe that might outground you vs a GFCI that will save you go ahead - but please put me in your will first

In the first paragraph you say a grounding probe removes stray voltage and then you say it's flawed. Do you mean that it will remove the voltage but the need for doing so is not definate? I don't know about the fish and corals but I just recently worked on a tank that was constantly giving me low voltage shocks. The reason was a non submersable heater be used as a submersable. I sure would have appreciated that probe. I don't really have an opinion on the effect on fish and corals though - don't know.

And lastly, I have both - I'm such a scaredy pants

[midgetwaiter]

I just wanted to add to what you had posted in the hopes of someone not getting confused. I have a habit of being pedantic about these because I work in the computer industry and just like reef keeping I think they are times where trying to summarize how something works opens the door to people making bad judgments. I'm sure you've noticed that a lot of the time when people discuss something like this with half an explanation you end up with nothing but hand waving and generalizations, may as well count on voodoo to save you. On the other hand maybe I'm just a jerk.

I would agree that a GFCI offers better protection than a ground probe.

The thing with the probe "removing" the current is complicated. I'm not convinced that if you have current in the tank but no path to ground that anything is harmed, like the bird on a wire. If you do ground it then you definitely have current flowing and I think from the view of the tank inhabitants that's probably worse. When you stick your hand in there, better to have the probe but if you tried in in a situation where you were not grounded at the time you'd never notice it.

[Dale]