Dennis, just as with Doctors, don't put them on a pedestal or assume they are always right simply because of a title.
Roger
To Bond the Pool Pump to the EPB Or Not
- Thread starter Dennis Alwon
- Start date
- Status
Roger
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
That's the truth. Not sure I had him on a pedestal but perhaps there was something to it. I just didn't quite understand what was being explained so I gave him the benefit of the doubt. Heck I am just a lonely EC...
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
That's the truth. Not sure I had him on a pedestal but perhaps there was something to it. I just didn't quite understand what was being explained so I gave him the benefit of the doubt. Heck I am just a lonely EC...
I read the
thread and in my thinking, the part about the pump being grounded/bonded to the grid and then having a fault. The fence was mentioned and the guy said if you were touching the fence with your hands and your feet was on the ground, you would be shocked. In my thinking, the fence, if metal, would be bonded too and you would have the "bird on the wire" effect. IOW, you, the fence, and the ground would be at the same potential. Regardless, as you stated, here in the US, the GFCI would trip.
Ask the guy why the pump motor has a bonding lug on it.
- Location
- Illinois
- Occupation
- retired electrician
If you are standing on the earth a couple of feet away from the energized fence and not on top of a bonding conductor in the earth, you will get a shock of ~50% of the voltage that is on the fence. The earth is not a good enough conductor to create the "bird on a wire" effect. For that effect to work you have to be able to raise the voltage of the earth to match that of the fence. Grounding and bonding does nothing to remove the voltage on the fence, other than to provide a low impedance fault path so that the OCPD will trip.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
I was thinking more on the lines of standing on the bonding grid and motor and fence were bonded.
- Location
- Illinois
- Occupation
- retired electrician
If you are actually on the bonding grid, you are fine, but if you are on the earth even a short distance from the bonding grid, you will be shocked.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
If that is the case why did they do away with the mat grid setup and allow one run 18" - 24" away from the pool. Sounds like that is worthless unless you are standing on the wire. That makes no sense
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
If I had to guess it is because there is no real answer to the problem. So they made a stab at doing "something".
Short of retrofitting all kinds of bad design and installation practices going back 100+ years, there is no good fix.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
- Location
- Illinois
- Occupation
- retired electrician
There was no technical substantiation to eliminate the grid and permit the use of a single bonding wire.
Under normal conditions, the single perimeter bonding wire will probably do the job. The normal conditions would be the low neutral to earth voltages that are common and that the equal potential bonding is designed to minimize the effects of.
Under fault conditions, it is unlikely you would be able to get out of the pool. I am not sure that even a bonding grid would make it safe.
There is no real answer as long as there is any type of electrical equipment that is associated with or near the pool.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Well we never hear about entire pools with floating bodies so either there is never a fault or something else is up.
- Location
- Illinois
- Occupation
- retired electrician
In a correctly installed system the fault should be quickly cleared. If you are in the water, you are probably ok under fault conditions, but if you are trying to get out of the pool by touching the concrete deck under fault conditions, you probably are not going to make it.
The same thing could happen with an open utility primary or secondary neutral in the area, but in that case the high voltage could last for an extended time as there is nothing to clear that type of "fault".
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
You can be in the water and touching the floor of the pool as in the lower end or a kiddie pool. Many kids hold on to the ladders etc. Wouldn't there be a potential difference between the bottom of the pool and the water itself-- to some degree at least.
- Location
- Illinois
- Occupation
- retired electrician
There may be voltage gradients in the water and between the water and the bonded metal parts. I am not sure how conductive the pool water is as compared to that of the earth.
- Status