bubblehead
Member
- Location
- Richmond, VA
I am a facilities mgr with 8 facilities and 19 swimming pools. We seem to be having a problem with what, in the pool industry, is generally refered to as bonding. Bonding as I know it is as follows, please correct me if I'm wrong:
* Bonding is not grounding. Bonding should not be connected to ground inside panels.
* Connects any metal part that touches pool water to the rebar frame of the pool.
* #8 solid wire is used and it is clamped to the rebar frame, splices, and any equipment that touches pool water.
* One inspector at one of our facilities had us bond the aluminum frames of the windows in the pool area. The use of a galvanized screw and copper clamp onto an aluminum frame passed inspection. There is no requiremrnt for brazing , soldering or welding any of these connections.
* Provides an "equaipotential" grid of the pool area "to reduce earth voltage gradients". I have heard some discussion of extending this grid to no less than 5' from the outside edge of the pool beam. Pool builders and construction electricians have not heard of it.
* It is easy to see an un-bonded metal component in a pool. It will rust or corrode to pieces in short order due to electrolysis or galvanic action.
The increased popularity of chlorine generation has made bonding, if that is the term I should be using, very important for control and longevity of our swimming pools for two reasons:
1. The increased conductivity of the water with up to 5000ppm of salt added turns the pool into a very large battery. The current (DC) will corrode doner metals and deposit the dissolved metal somewhere else. This process will continue until all of the doner metals have been corroded completely. Copper and aluminum are very susceptible and go first.
I look to bonding to NEUTRALIZE this current by effectively shorting out the DC voltage between these metalic components. Somehow, the DC voltage has to be held to 0v by the bonding. I don't see any room for poor connections in the grid anywhere.
2. Pool automation works by measuring small DC voltages in the water - from 600-800mv DC for chlorine and pH measurments. The bonding should keep the stray DC voltage to zero, if it works like I think it does, but we also need to eliminate the AC component that may be present from ground current, either direct or induced. We are begining to see pools at about five years old that begin to pick up stray voltage in the water and causes the sensor probes to not track. I'm thinking corroded bonding connections under the pool
We have taken some steps to deal with the problem - installing harmonic rejection transformers for pool equipment room panels and eliminating pool-water reheat form the rooftop dehumidification units (eliminates copper pipe connection from hi voltage to low voltge pool equipment) but results are not in yet because these are newer facilities. We also cleaned the bonding connections on all of the equipment at an older facility and saw a reduction on the wandering of the sensors but it was not eliminated.
Can we talk about this?
Thanks
* Bonding is not grounding. Bonding should not be connected to ground inside panels.
* Connects any metal part that touches pool water to the rebar frame of the pool.
* #8 solid wire is used and it is clamped to the rebar frame, splices, and any equipment that touches pool water.
* One inspector at one of our facilities had us bond the aluminum frames of the windows in the pool area. The use of a galvanized screw and copper clamp onto an aluminum frame passed inspection. There is no requiremrnt for brazing , soldering or welding any of these connections.
* Provides an "equaipotential" grid of the pool area "to reduce earth voltage gradients". I have heard some discussion of extending this grid to no less than 5' from the outside edge of the pool beam. Pool builders and construction electricians have not heard of it.
* It is easy to see an un-bonded metal component in a pool. It will rust or corrode to pieces in short order due to electrolysis or galvanic action.
The increased popularity of chlorine generation has made bonding, if that is the term I should be using, very important for control and longevity of our swimming pools for two reasons:
1. The increased conductivity of the water with up to 5000ppm of salt added turns the pool into a very large battery. The current (DC) will corrode doner metals and deposit the dissolved metal somewhere else. This process will continue until all of the doner metals have been corroded completely. Copper and aluminum are very susceptible and go first.
I look to bonding to NEUTRALIZE this current by effectively shorting out the DC voltage between these metalic components. Somehow, the DC voltage has to be held to 0v by the bonding. I don't see any room for poor connections in the grid anywhere.
2. Pool automation works by measuring small DC voltages in the water - from 600-800mv DC for chlorine and pH measurments. The bonding should keep the stray DC voltage to zero, if it works like I think it does, but we also need to eliminate the AC component that may be present from ground current, either direct or induced. We are begining to see pools at about five years old that begin to pick up stray voltage in the water and causes the sensor probes to not track. I'm thinking corroded bonding connections under the pool
We have taken some steps to deal with the problem - installing harmonic rejection transformers for pool equipment room panels and eliminating pool-water reheat form the rooftop dehumidification units (eliminates copper pipe connection from hi voltage to low voltge pool equipment) but results are not in yet because these are newer facilities. We also cleaned the bonding connections on all of the equipment at an older facility and saw a reduction on the wandering of the sensors but it was not eliminated.
Can we talk about this?
Thanks