Re:grounding probe

Dear John:

Yikes! I’m sorry to hear you got jolted, sir — no doubt that was a most unpleasant surprise, to say the least!

But I think you are mistaken in attributing the shock to your grounding probe, John. A titanium grounding probe is not electrified, sir; it’s not a live wire at all. The best analogy I can give you is that your grounding probe is like a lightning rod for your aquarium.

Just like the lightning rod on your house, the grounding probe is not part of an electrical circuit. A lightning rod is not electrified and is not a live wire — it is just a good conductor attached to the highest point on your house at one end and then safely grounded at the other end. Under normal conditions, it’s completely inert and inactive. It’s only purpose is to provide a safe pathway for the electrical discharge should your house be struck by lightning. In that event, the electricity from the lightning strike will follow the path of least resistance, which is the lightning rod, from the rooftop to the ground, where it will be discharged safely, thus preventing damage to the house or injury to its inhabitants from a bolt of lightning.

Well, a grounding probe fulfills the same purpose for your aquarium and works in exactly the same way as the lightning rod on your house. When all goes well, the grounding probe is completely inert and inactive. It merely serves as a good conductor that will provide the path of least resistance from the aquarium water to a safely grounded outlet. If any of the aquarium equipment were to short-circuit, the grounding probe would safely channel the electrical discharge away from the aquarium and into the ground wire for the outlet, thereby protecting the aquarium and its inhabitants from harm when there is electrical accident. That is the only time when the grounding probe is active, and its sole function is to provide the path of least resistance and safely channel the electricity away from the aquarium.

I don’t know what type or model of grounding probe you may be using, John, but all of the ones I am familiar with have the same design. There is a slender titanium rod at one end, which goes in the aquarium water, and this titanium rod is attached to a 3-pronged plug at the other end by a length of wire perhaps 10 feet long. As we have been discussing, the 3-pronged plug for the grounding probe is then plugged into a grounded outlet, just like any other plug. However, the 3-pronged plug for the grounding probe differs from other plugs in that the twin prongs that correspond to a normal 2-pronged plug and that plug into the usual receptacle in the outlet to complete the electrical circuit are not made of metal; rather, they are made from a good insulator, which thereby prevents the electrical circuit from being made when you plug in the grounding probe. It is only the third prong on the grounding probe that is made of metal, and when you plug it in, it connects to the grounding wire for the outlet.

All of which means that the grounding probe is not electrified and is not a live wire, and it can thus not cause an electrical shock. The worst thing that can happen is that, if the grounding probe is not connected properly, or is connected to an outlet that is not grounded, it will fail to prevent an electrical shock from being conducted through the aquarium water when a piece of equipment short-circuits.

I should also explain that the probe only grounds the aquarium water. So even when a grounding probe is connected to a grounded outlet properly and is functioning normally, you can still get a shock from touching the lighting fixture, for example, since the lighting fixture is not in contact with the aquarium water and is thus not protected by the grounding probe (unless the aquarium light were to fall into the tank).

In your case, John, it seems that one of the pieces of equipment for your aquarium is malfunctioning or short-circuiting, and that’s what caused you to be shocked. In my experience, it is the aquarium heater that is responsible for most such problems, typically when the casing is cracked. But submersible water pumps or powerheads can also be the culprit at times, as can a short-circuiting light fixture, particularly in a marine aquarium when salt deposits begin to accumulate on the light and eventually make a salt bridge between electrical components.

So that’s where I would begin in tracking down the problem in your case, sir. Whatever you do, do not let the tank go without filtration and water circulation for an extended period for the sake of the aquarium inhabitants.

Best of luck getting your aquarium up and running properly again, John, with no shocking developments!

Respectfully,
Pete Giwojna

Post edited by: Pete Giwojna, at: 2011/02/13 00:03