Electrical Terminology & Safety Tips

[sturev]

Thanks BTDG & Poconos!

What's the deal with bonding? I'm not sure I understand the significance of that and I certainly don't understand reasoning (if that's different than significance )...

[Poconos]

The bonding or grounding issue is tying all the grounds together so you cannot have a voltage difference between different devices. You cannot rely on a ground rod driven into the earth at each device because the earthen ground may have a high resistance depending on the dampness and surface area of the ground rod or plate itself. Everything should be tied together with a copper ground wire. It's interesting in densely populated areas to take an AC voltmeter and stick one of the probes into the ground and the other some distance away like 100' or so. Not unusual to read several volts. Another interesting exercise is to take a clamp-on ampmeter and measure the currents in the ground wire on any power pole that has a transformer on it. You'll read something. In a perfectly load balanced electrical system you should see nothing. I've babbled enough.

Hope this explains it better. We'll keep modifying the original post as we find the need to clarify or change things.
Al

[sturev]

Have you heard of bonding non electrical components? I have a hydralic pump in my pool (counter current swim machine), and while there's no power to it, they wanted it bonded to the metal frame of the pool, and then they wanted the pool frame bonded to all the other componets (pump, heater, etc)... There's even a stainless steel handle on the swim machine (it's attached to plastic, not touching any other metal), and they wanted that bonded to the rest of the system...? BTW, the hydralic lines are rubber of course... Any thoughts on that?

[Poconos]

I'm one that believes in common sense and have trouble with some codes. Just ask CarlD. Can't say I ever dug into grounding codes and initially it may not make sense to tie non-electrical components together but......considering pool water is a conductor of electricity and it doesn't take much current to zap somebody and pool water is in contact with electrical components somewhere in the system, maybe it does make sense. I can't say one way or another.
Al

[CarlD]

In my town EVERYTHING metal must be bonded--unless it's not attached, like a solar reel.

But my ladder, my drop-in steps handrails, the pool structure, cross members ALL had to be bonded, as well as, of course, the pump.

Codes don't always make sense but they always must be obeyed to the inspector's satisfaction (!).

Insurance companies won't pay a claim if you needed a building permit and didn't get one. It's as simple as that. If you have an "outlaw" pool and someone gets hurt, Ol' Indemnity Plus will let you swing in the breeze.

[BigTallGuy]

The main idea is to ground all the various components of your pool together with copper wires. You can use Bare or insulated wires, and somewhere there could be a code dictating a wire size, but in my mind, all these grounding wires need to be grounded directly to the GFCI ground wire or the (Green) Grounding screw. Twist them together, use wire nuts, crimp them together, even solder them, but the "Final Run" goes back to the GFCI.

[Ohm_Boy]

Bonding and grounding are often confusing subjects, and are not the same.

Bonding refers to connecting items together. All metal objects which can come into contact with pool water should be bonded together. This prevents any one of them from becoming a different potential from any other, from whatever influence, direct electrical contact, induced current, chemical, etc. This bonding prevents any current flow through the water itself, thereby protecting the occupants.

Grounding, on the other hand, indicates a connection of one or more components to the service ground, equipment ground, ground rod, or other ground-potential reference point. Technically, there should only be one ground reference in an electrical installation, and that is most often at the service feed point. Everything else which is to be grounded should tie directly to that point with minimum resistance.

Technically, in a grounded system, bonding is simply a means of connecting the ground wires to everything. In an ungrounded system, a bond wire just connects it all.

There is also much debate over whether or not a bonded pool grid is to be grounded, and as I understand it, there are differing local code requirements as well. Some say ground, some say isolate. I'm personally a "ground it" fan.

As an aside, the GFCI protected circuit does not need a ground connection to the GFCI to be protected. GFCI devices are designed to measure differential currents between the hot and neutral conductors, and open the circuit if that difference exceeds the trigger, around 5 milliamps. It is assumed that any difference in current is being diverted out-of-circuit by a body somewhere. Naturally, a ground is required by the circuit according to code, but it is not necessary for the GFCI feature to function.