Equipotential Bonding of Submersible Pool Pump

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jrohe

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Professional Engineer
Guys and gals, I've got a strange one that I was hoping to get some input on. We are working on the design of a very large wave pool that is going to have twenty-two 150 horsepower pumps. The pumps are completely submerged in the wave pool and do not have any metallic piping connected to them. For equipotential bonding purposes, the pump manufacturer has designed an exposed connection point on the outside of the submersible pump housing to land a bonding wire on. The manufacturer is also providing a cable whip which includes a grounding conductor for equipment grounding connections.

We initially proposed using insulated #8 solid copper wire and encapsulating the termination in marine-grade epoxy but the contractor believes this may be an installation and maintenance issue and is hoping to just use a bare #8 solid copper wire. However, we believe that bare copper submerged in chlorinated water may cause the wire to deteriorate rapidly, especially if high concentrations of chlorine are used to "shock" the wave pool water.

Does anybody have any trade secrets on how these submerged pumps could be equipotentially bonded?
 
An encapsulated 8 awg to the pump, perhaps 4 ft long, to splice to the bond wire. Would XHHW be a better insulationation than THHW/N?
Replacement pump would have long bond wire.
 
jrohe said:
Guys and gals, I've got a strange one that I was hoping to get some input on. We are working on the design of a very large wave pool that is going to have twenty-two 150 horsepower pumps. The pumps are completely submerged in the wave pool and do not have any metallic piping connected to them. For equipotential bonding purposes, the pump manufacturer has designed an exposed connection point on the outside of the submersible pump housing to land a bonding wire on. The manufacturer is also providing a cable whip which includes a grounding conductor for equipment grounding connections.

We initially proposed using insulated #8 solid copper wire and encapsulating the termination in marine-grade epoxy but the contractor believes this may be an installation and maintenance issue and is hoping to just use a bare #8 solid copper wire. However, we believe that bare copper submerged in chlorinated water may cause the wire to deteriorate rapidly, especially if high concentrations of chlorine are used to "shock" the wave pool water.

Does anybody have any trade secrets on how these submerged pumps could be equipotentially bonded?
Click to expand...
I'm interested in the manufacturer and model of this pump. Way out of my league, but I'm interested. Perhaps you post that.

In regards to bonding this pump, being it's submerged, I would treat it like a wet niche pool light bond lug and apply potting compound. Yeah, will be a PIA if the pump has to be serviced or changed, but that's the cost to have system such as this.

Yes, the chlorine will corrode the lug over time. If the wave pool is to be outfitted with a salt water chlorine generator, the salt can certainly accelerate corrosion. Prolonged acidic conditions can do damage. More than likely there's a sophisticated automated chem system in place to prevent that.
 
tom baker said:
An encapsulated 8 awg to the pump, perhaps 4 ft long, to splice to the bond wire. Would XHHW be a better insulationation than THHW/N?
Replacement pump would have long bond wire.
Click to expand...
Tom,

Thank you for your reply. I am glad to hear we were not completely off base with what we were proposing. Yes, we were also thinking XHHW. Or possibly marine grade wire with tinned copper strands, if the AHJ will permit the stranded wire in lieu of the code-required solid conductor, for added corrosion resistance.

Jason Rohe, P.E.
 
Mystic Pools said:
I'm interested in the manufacturer and model of this pump. Way out of my league, but I'm interested. Perhaps you post that.

In regards to bonding this pump, being it's submerged, I would treat it like a wet niche pool light bond lug and apply potting compound. Yeah, will be a PIA if the pump has to be serviced or changed, but that's the cost to have system such as this.

Yes, the chlorine will corrode the lug over time. If the wave pool is to be outfitted with a salt water chlorine generator, the salt can certainly accelerate corrosion. Prolonged acidic conditions can do damage. More than likely there's a sophisticated automated chem system in place to prevent that.
Click to expand...
Mystic Pools,

Thank you for your reply. As I stated to Tom, I am glad to hear we're not off base with what we are proposing. As requested, I have attached a PDF file cut sheet of the pump. I have also included a photo of the ground clamp the manufacturer will be providing for the equipotential bonding.

Honestly, we do not think the equipotential bonding wire is going to accomplish anything. The pool water is equipotentially bonded and the pump is completely submerged in the bonded pool water, which would mean the pump is, therefore, bonded. However, the bonding wire is code required and, as such, we want to make sure it is done right.

Jason Rohe, P.E.


Ground Clamp.jpg
 

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If you don't think the bonding wire is going to do any good what difference does it make whether you use solid or stranded or what insulation is used on it if you decide to use insulated wire?

My inclination is to follow the code. The code says it has to be solid it has to be solid. Someday when somebody gets electrocuted in your pool it's going to be a lot easier to not have to justify that you deliberately violated the electrical code.
 
jrohe said:
Mystic Pools,

Thank you for your reply. As I stated to Tom, I am glad to hear we're not off base with what we are proposing. As requested, I have attached a PDF file cut sheet of the pump. I have also included a photo of the ground clamp the manufacturer will be providing for the equipotential bonding.

Honestly, we do not think the equipotential bonding wire is going to accomplish anything. The pool water is equipotentially bonded and the pump is completely submerged in the bonded pool water, which would mean the pump is, therefore, bonded. However, the bonding wire is code required and, as such, we want to make sure it is done right.

Jason Rohe, P.E.


View attachment 2555813
Click to expand...
Thanks Jason. Interesting that this pump is used mostly for industrial use, but it works for a wave pool.

There could be an argument the water is bonded and therefore the pump, being submerged, does not require it. But, it is the code and I would follow it to the letter. The water bond could fail. Then what? CYA. The cost and effort to attach the bond wire to that pump is minimal, compared to what you could be faced with liability-wise. CYA!!!! Documents. Photos of everything.

I'm interested in seeing the "whip" they are providing for the bond connection.

I'm guessing this pump is dropped into a pipe, and the water is drawn in from the top of the flange and discharged at the base. There must be a way they want is to be held in place. That's a lot of water being moved.

I researched the pump company. I did not see any UL or ETL certifications. It's a European company. Perhaps worth a look.
 
Just to be clear, I am not proposing violating code. As I stated, " However, the bonding wire is code required and, as such, we want to make sure it is done right." I just thought I would solicit the input from this group to see if anyone else had any other ideas other than encapsulating the ground connection at the pump in marine-grade epoxy/potting compound.

Jason Rohe, P.E.
 
jrohe said:
Just to be clear, I am not proposing violating code. As I stated, " However, the bonding wire is code required and, as such, we want to make sure it is done right." I just thought I would solicit the input from this group to see if anyone else had any other ideas other than encapsulating the ground connection at the pump in marine-grade epoxy/potting compound.

Jason Rohe, P.E.
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Understood.

3M makes a potting compound. Comes in 2 packets you mix together. Work fast! Sets up quickly. It's a sticky black material.

Aquabond makes a potting compound that comes in cartridge. You will need the mixing gun to apply it. You can encapsulate multiple bond points with the cartridge. 3M is one and done.
Aquabond may be best for this job, as you have multiple pumps. We used this when we were installing wet niche pool lights. The last 15 years though, we only install nicheless, 12V LED lights, which do not require bonding.

Wet Niche Potting Compound | Pool Light Potting Compound

Looking for a wet niche potting compound? We've got you covered! Shop wet niche potting compound for pool lights with AquaBond Adhesives now!
aquabondadhesives.com aquabondadhesives.com

Hope this helps you out.
 
Mystic Pools said:

Looks like 3M now has it in cartridge form too

Another kit

3M Scotchcast Potting Kit, 3M 2136, 80-6114-6849-9 | Hillas.com

Buy 3M Scotchcast Potting Kit 2136, (1.5 oz) at Hillas.com. Free Shipping on Qualified Orders.
www.hillas.com www.hillas.com


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I’ve used the 3M cartridge type.

Word of caution to the OP; you’ll need to make the connections with the lug facing up and find something to put around the lug to hold it until it sets. That compound has a consistency like that of latex paint.

I’ve never used it on lugs like this, but I did some split bolt connections awhile back while repairing pool light connections inside brass deck boxes. I bought a large rubber ice cube tray, cut out each cube square and put the connectors in the tray. Then filled the tray with the potting compound. It did not take long to set up.


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It definitely needs a solid wire and I believe it needs to be green coated so the water doesn't damage the bare copper. It will mostly likely be TW wire as that is all I can really find in #8 solid green. I personally like the Aquabond brand that comes in a cartridge much better than the 3m stuff. You can just smear the potting compound on the lugs and it might sag a little but it will stay in place until it cures.

Wet Niche Potting Compound | Pool Light Potting Compound

Looking for a wet niche potting compound? We've got you covered! Shop wet niche potting compound for pool lights with AquaBond Adhesives now!
aquabondadhesives.com aquabondadhesives.com
 
SSDriver said:
It definitely needs a solid wire and I believe it needs to be green coated so the water doesn't damage the bare copper. It will mostly likely be TW wire as that is all I can really find in #8 solid green. I personally like the Aquabond brand that comes in a cartridge much better than the 3m stuff. You can just smear the potting compound on the lugs and it might sag a little but it will stay in place until it cures.

Wet Niche Potting Compound | Pool Light Potting Compound

Looking for a wet niche potting compound? We've got you covered! Shop wet niche potting compound for pool lights with AquaBond Adhesives now!
aquabondadhesives.com aquabondadhesives.com
Click to expand...
Exactly. Aside from getting multiple uses out of it, it does not sag like the 3M kit. It pre-mixes in the cartridge so messing around.
 
Thank you all for your input! Everyone on this forum is awesome! We are proceeding with the solid insulated #8 AWG copper conductor with all underwater terminations encapsulated in potting compound. It does present difficulties in initial installation and maintenance, specifically if/when a pump needs to be replaced. However, this is really the only option to achieve a safe and code-compliant installation.

Jason Rohe, P.E.
 
Mystic Pools said:
I researched the pump company. I did not see any UL or ETL certifications. It's a European company. Perhaps worth a look.
Click to expand...
Sulzer bought the former Ahlstrom pump, and has some manufacturing capability in Easley SC. They are a major player in the water and wastewater industry. I believe they lead in hydroelectric generation, and ISTR that Duke Energy replaced the pumped storage turbines with Sulzer products some 5 or 10 years ago. To not have UL or ETL certification would be surprising, but perhaps in that industry it isn't required?
 
GeorgeB said:
Sulzer bought the former Ahlstrom pump, and has some manufacturing capability in Easley SC. They are a major player in the water and wastewater industry. I believe they lead in hydroelectric generation, and ISTR that Duke Energy replaced the pumped storage turbines with Sulzer products some 5 or 10 years ago. To not have UL or ETL certification would be surprising, but perhaps in that industry it isn't required?
Click to expand...

I can tell you, the pool pumps I use, are ETL listed and NSF certified.

The Sulzer pump, normally used in industrial applications, is now being utilized for a bathing application.
I'm not sure if used that way, it must ETL or UL listed?????? Or NSF ???
 
jrohe said:
Mystic Pools,



Honestly, we do not think the equipotential bonding wire is going to accomplish anything.

Jason Rohe, P.E.


View attachment 2555813
Click to expand...
As a side note on the # 8 equal potential bonding for pools.

We have been accustomed to pointing out that there is no code requirement to extend this bonding conductor to the pool equipment supply panels equipment grounding bar. And that is in fact true in regards to the min code language.

We do however find an absolute requirement that the equal potential bonding be connected to the premise equipment grounding system. One point that connection is insured is through the pool pumps exterior grounding terminal when pool pumps are not double insulated pool pumps

As you being an engineer I would consider steeping out side of the NEC min and the easiest way to ensure a solid connection between the equal potential bonding and the premises equipment grounding system is to extend the # 8 copper to the equipment ground buss of the supply panel
 
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