POOLS and grounding and GFCI

[dm9289]

I have been doing some study of the code rules involving pools plus a couple hours of video. I am understanding better the need for a low as possible ground fault impedance path to trip breakers. The authors stressed this and the voltage gradient.

From my understanding most if not all electrical equipment in the area will be fed by a GFCI breaker or GFCI receptacle wouldn't this be the most important element?

From videos they showed situation with say 3v to ground on railing, My guess with body resistance it may be below 6ma threshold for GFCI but not enough current to seriously injury? Please feel free to blow holes in this theory

If it was above 6ma GFCI threshold power would shut off due to tripped GFCI>
Again Please feel free to blow holes in this theory


Thank you as always for educating me

 

[Danielt]

I'm not sure I understand your question.
GFCI protection is extremely important, especially at a pool. The equipotential bonding at a pool is just as important, partly to assure those GFCIs work.
3 volts on the railing wouldn't even be felt. If the amperage is enough, the GFCI trips. A very safe system if installed correctly.

 

[dm9289]

I'm not sure I understand your question.
GFCI protection is extremely important, especially at a pool. The equipotential bonding at a pool is just as important, partly to assure those GFCIs work.
3 volts on the railing wouldn't even be felt. If the amperage is enough, the GFCI trips. A very safe system if installed correctly.

you mentioned the equipotential ground is important for a GFCI to trip. I thought the tripping of a GFCI is simply a function of hot and neutral current not being equal.

So what I'm saying is appears to me if GFCI worked properly even with no ground connection whatever path the current found once it reached about 6ma it would trip and all would be safe. I understand I'm likely missing the boat here but I'm having trouble understanding this.

 

[Little Bill]

you mentioned the equipotential ground is important for a GFCI to trip. I thought the tripping of a GFCI is simply a function of hot and neutral current not being equal.

So what I'm saying is appears to me if GFCI worked properly even with no ground connection whatever path the current found once it reached about 6ma it would trip and all would be safe. I understand I'm likely missing the boat here but I'm having trouble understanding this.

A GFCI tripping and equipotential bonding are two separate things. Yes you want, and are required in most cases, to GFCI protect the circuits. But the equipotential bonding is different. With it, you are trying to make everything that could be energized on an equal plane with no potential difference between them. Same principle as a bird sitting on a live wire. As long as it doesn't come in contact with another wire, or anything with a different potential, there is no shock hazard. A voltage in and around a pool is not always from the equipment or even the system from the house/building. It could be a bad conductor from the POCO leaking voltage in the ground. When you bond everything in and around the pool, including the water, you take away the risk of being shocked as everything would be at the same potential.
Something GFCI protected may or may not trip due to stray voltage and GFCI protection is not related to equipotential bonding.

 

[dm9289]

A GFCI tripping and equipotential bonding are two separate things. Yes you want, and are required in most cases, to GFCI protect the circuits. But the equipotential bonding is different. With it, you are trying to make everything that could be energized on an equal plane with no potential difference between them. Same principle as a bird sitting on a live wire. As long as it doesn't come in contact with another wire, or anything with a different potential, there is no shock hazard. A voltage in and around a pool is not always from the equipment or even the system from the house/building. It could be a bad conductor from the POCO leaking voltage in the ground. When you bond everything in and around the pool, including the water, you take away the risk of being shocked as everything would be at the same potential.
Something GFCI protected may or may not trip due to stray voltage and GFCI protection is not related to equipotential bonding.

I think you helped me, let me tell you what I got.

If there is leakage current due to a power source associated with pool you will likely activate GFCI and protect people

If there is leakage current from a source such as the power company there is no GFCI or fuse or breaker to protect personnel if that potential difference becomes large.

If there is POCO leakage say 10v and all things are bonded ladder, cement, shell, pump, water etc. 10V may be present but no potential difference to create shock between pool parts cement etc

Please feel free to correct or add

 

[frofro19]

A GFCI tripping and equipotential bonding are two separate things. Yes you want, and are required in most cases, to GFCI protect the circuits. But the equipotential bonding is different. With it, you are trying to make everything that could be energized on an equal plane with no potential difference between them. Same principle as a bird sitting on a live wire. As long as it doesn't come in contact with another wire, or anything with a different potential, there is no shock hazard. A voltage in and around a pool is not always from the equipment or even the system from the house/building. It could be a bad conductor from the POCO leaking voltage in the ground. When you bond everything in and around the pool, including the water, you take away the risk of being shocked as everything would be at the same potential.
Something GFCI protected may or may not trip due to stray voltage and GFCI protection is not related to equipotential bonding.

That's the best explanation I've heard yet.

 

[kwired]

Now keep in mind if nothing is in abnormal operation, you still can have small amount of volts on your service grounded conductor simply because of voltage drop, could be drop on the grounded service conductor or even drop on POCO's MGN from the primary neutral, since the MGN and your grounded service conductor are bonded together at the source they effectively are one and the same conductor so if there is 3 volts to earth on the MGN, there will be same three volts on everything bonded to it including the EGC's in all your premises wiring and anything else bonded (intentionally or accidentally) to the EGC, GEC grounded service conductor. That will put 3 volts to earth on all the equipotential grid of your pool, but as earlier described if done correctly everything within reach of pool users will also be at that same 3 volts so no touch potential to the users.

A "hole" in the equipotential bonding grid is where you may be subject to that three volts. A small "hole" might not be much of a thing in some circumstances at only three volts, but start increasing the voltage and it can be.

In theory the entire pool could be sitting there at 100 or even 1000 volts above "earth" and you are still safe in properly bonded pool system, though 1000 volts will definitely test the installer for holes in the bonding more so than 100 volts will.