Swimming Pool Construction Expert Discusses Electrical Safety, Bonding Grid, Galvanization - by: International Aquatic Consultant Paolo Benedetti

Metallic Staining and Galvanic Corrosion are usually a result of current reaching the aquatic facility or swimming pool.

Unintentional Stray Current

How does stray current find it's way to the pool?  Modern electrical systems incorporate a continuous grounding system.  The grounding conductors are all tied together, creating a grounding network.  

The pool and any out buildings are usually connected to the same grounding network.  Therein lies the problem.  A minor short circuit in an appliance, outlet or other electrical device that is insignificant to trip a breaker, will send electricity to the grounding network - which includes the pool.

A pool's bonding grid can become energized, since the grounding network and equipotential bonding grid are interconnected in numerous places throughout an aquatic facility.  Primarily they are connected together at automation panels, electrical pool components, pool pump motors and lighting components.

Intentional Stray Current

Stray current can be intentionally introduced into the pool water by salt chlorine generators and electronic ionizers.  These devices utilize electrically charged metals to induce their desired result.  A major drawback is that by introducing electricity into the water, they can actually initiate galvanic corrosion or electrolysis.

Importance of a Bonding Grid

If a equipotential bonding grid is installed correctly and a bonded component becomes energized, personnel are still safe.  This is even though electricity is still present to create a galvanic reaction or plating conditions between dissimilar metals.

Sacrificial Anodes are NOT for pools

The purpose of a sacrificial anode, is to give of itself freely to save another component.  However, you are simply introducing another metal into the aquatic environment.  These less noble metals are usually maganese, magnesium or zinc.  They will dissolve into the water, where they will stain finishes or plate metallic components.

Shouldn't you simply eliminate the source of the stray current instead?
 
References:

http://www.atcoelectric.com/Safety/Contractor-Safety/Documents/070301%20ssm%20Equipotential%20Bonding.pdf

https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_id=9871&p_table=STANDARDS

http://www.nickelinstitute.org/~/Media/Files/TechnicalLiterature/StainlessSteelinWatersGalvanicCorrosionandit%20PreventionAEBauer.pdf

http://www.npl.co.uk/upload/pdf/bimetallic_20071105114556.pdf

Paolo Benedetti, SWD, Principal 
Aquatic Technology Pool and Spa © 
www.AquaticTechnology.com 
International Aquatic Consultant, Watershape Engineering, Swimming Pool Design, Expert Witness, Hydraulic Designer, Landscape Design, Owner's Rep 
Office: 408-776-8220 
Email: info@aquatictechnology.com 

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