Wow, guess I really stirred the pot up here. My goal is not to cut down on others practices, but to give the correct information on the subject so that others can make their own decisions.
First let’s talk about a GFCI and how it works. There seems to be a lot of miss information floating around.
A GFCI measures the current flow from your hot to neutral (or grounded) conductor. The little round hole in the outlet that the ground prong of a plug goes into is for the “grounding†conductor. There is a HUGE difference. A GFCI has a solid-state device in it that monitors the current going too the device and the current leaving the device. This amount falls within certain limitations. If the GFCI detects an abnormality in this it trips. It has NOTHING to do with the ground prong, plug, wire, etc.
Example:
If you have an old house with the old two slot outlets, you can change that outlet out to a GFCI and it will work. Is that code, no, but it will work properly. Note: I do not recommend this.
Next
I’m going to go into the whole “double insulated†thing a little deeper. I’ll use a corded drill for an example.
If you have an ALL-plastic drill housing it is considered to be double insulated. This is because there is no reasonable way for any current carrying parts of the drill to come into contact with the operator. This means that even the chuck of the drill will be coated in plastic OR be separated from the motor by plastic gears, etc.
Now if you have a drill with a metal housing or a combination of metal/plastic you will have a grounded plug. This is so that if, no matter how slim the chance, one of the current carrying parts of the drill comes into contact with the housing the fault current will be directed to the grounding conductor of the circuit and not the user.
UL, CPSC, and other test facilities around the world favor the double insulated method. It’s safer for the layperson. Now just because something is double insulated dose not make it foolproof. If something catastrophic happens, say a heater breaks; it’s not going to be good, like in cczarnik’s case. Chances are that it wasn’t the current in the tank that kill it, but the coating on the heater elements and the heater guts breaking down that polluted the tank. And I’d bet a 6 pack of your favorite drink that if he had a ground probe the same thing would have happened. On a side note, sorry to hear about that.
Having a ground probe will not trip a GFCI if there is a bad device in your tank. They just don’t work that way. On the other hand, a arc fault breaker is, but that’s a new topic.
Moving on.
Stricknine said:
As per Canadian and National electrical code (CEC in Canada, NEC in US), all metal in an electrical system must be grounded because it is conductive, and this rule should pass on to water as it is the same concept. In addition, in electrical code books there is a TON of grounding requirements for swimming pools: all water, metal, and current carrying material MUST be grounded within a certain radius of the pool SO if there is a fault it is a tripped circuit and not a live wire.
Last I checked you don’t ground a swimming pool. You are required to ground the equipment FOR a swimming pool. That way if the equipment for the pool fails and causes a fault it has a good grounding source to go to and doesn’t go to the pool or its occupants for it. That’s a bad comparison anyway. You don’t put electrical devices in a swimming pool with the exception of built in light’s etc. What you have to understand is that it’s not about grounding the water, it’s about grounding the device and preventing the stray voltage going to the water. The water is a pool is grounded naturally by the concrete, liner, etc. that incases it.
Stricknine said:
- If you have faulty equipment and don’t have the tank grounded, you will never know. Ground the tank and the GFI will pop within milliseconds of the live wire hitting the surface.
Nope.
First, your tank is not a means of circuit protection. Second, it won’t trip the GFI unless both the hot and the neutral of the same circuit are put in the water. GFI’s have nothing to do with the ground. Third, you would probably trip the breaker with a grounded tank and a hot wire put into it.
In closing, AC current in a tank is not going to randomly zap fish and corals. Electricity is looking for one thing, ground. The earth is the only thing that has enough area to dissipate it. It’s when a fish, coral, people, etc get in the way of electricity getting to ground that there’s a problem.
I am confident that if you put a live wire in an isolated tank that there would be no ill effects. If there is nowhere for the current to go, then there is no potential. It’s no different than if you have an extension cord plugged in and the other end is lying on your living room floor. It doesn’t randomly zap people walking around. It’s only if someone comes in contact with the current carrying conductors and provides a source for ground that you’d have a problem.
Like I said before, I’m just stating the facts and honestly trying to help. I don’t want any hard feelings. Let’s face it; no one wants to see anyone get hurt.
It is a scarry thing when well qualified electricians can't agree on the same principles.
