Equipotential Bonding

[MBPoolGuy]

I've been building steel reinforced concrete pools for 20 years but have never really taken the time to research and understanding the details of bonding - so i need help.

Yesterday I came upon a situation that I have never seen ...

We built a concrete pool inside 10 raised concrete structure engineered & built to have us build a pool inside it. After waterproofing the inside of the existing structure, we installed our rebar grid inside the structure and, as normal, ran #8 copper & bonded it to the the steel at 4 points, passed inspection and shot the pool leaving the copper leads outside bond beam to tie on the copper bonding loop. However, the home builder hired a deck contractor who has installed a porcelain paver tile as the deck mudded on top of a waterproofing system which itself was installed on top of 4" thick structural styrofoam to create the slope. But the deck contractor did 2 things that now have me in a bind:
1) did not call for a deck bonding inspection
2) Cut off 3 of the 4 copper leads - So now I can not attach the bonding loop even if I have them remove the paver tile and styrofoam.

So, given all that, here is the question - With none of the pool actually touching the earth and the porcelain being on top of styrofoam, is the deck bonding loop actually necessary? Or can we just take the last lead and run it back to the pool motor, heater, etc ... ? or any other solutions other than tearing up the deck, chiseling out part of the pool shell in 3 places and reconnecting to the 3 leads.

Thanks in advance for any help..

 

[mknauss]

Welcome to the forum.

I am not a bonding expert, but let’s ask for some other members to chime in.
@JamesW @ajw22

 

[ajw22]

Welcome to TFP.

Is this a single family residential building with an indoor pool or an apartment building or commercial structure?

The only authority to give you the answer are the Inspectors who will need to approve the electrical and bonding on the structure.

The buildings engineering plans should have included electrical plans for the pool that included all bonding.

This forums focus is on outdoor residential pools and does not see the type of problem you have. Most pool bonding articles deal with outdoor pools.

A good reference is from Mike Holt Enterprises on Article 680—Swimming Pools, Spas, Hot Tubs, Fountains, and Similar Installations.

Also How to Verify That a Pool is Safe from Electric Shock – In Accordance with the National Electrical Code from Mike Holt.

Mike Holt runs his own website at Mike Holt Enterprises - The Leader in Electrical Training. and has a forum at Mike Holt's Forum that can be read by all but only licensed electricians are allowed to post. You can message Mike at the site and see what advice he can provide or get an electrician to post on their forum.

If you would have asked me before the deck was installed I would have suggested that a copper wire mesh bonding grid be placed in the mud under the pavers and connected to the pool bonding leads and equipment bonding.

Copper mesh wire grid is often used under paving stones to fulfill the NEC requirement. Made of #8AWG solid copper wire with exothermically welded joints, copper mesh also must be connected to the equipotential bonding grid. Direct burial connectors (split bolts and rebar clamps) must be used, and are typically included with copper mesh kits.

Like...

3′ WIDE X 100′ LONG COPPER EQUIPOTENTIAL BONDING GRID W/KIT <span> Case Qty. 1</span> - Consolidated Manufacturing

KIT INCLUDES 20 #8 SPLIT BOLTS, 16 METAL STAKES Case Qty. 1 AVAILABLE IN CUSTOM LENGTHS ; 50’. 125’, 150’, ETC.

www.cmiwebsite.com

https://www.greaves-usa.com/wp-content/uploads/2020/03/82.pdf

https://www.greaves-usa.com/wp-content/uploads/2015/09/FAQMesh.pdf

Good luck and let us know how this turns out.

 

[klanel]

I would say it's a liability issue at this point and should be corrected. As for checking grounds, I think someone with a megger could check it and determine if the 'field of effect' for the ground system is adequate but if it were me, I would be hesitant to make the connections active with the potential for injury. I retired from an electric utility and we had someone that specialized in issues like this when people would get shocked in/around their pools. We would go out for free to assist with identifying and resolving issues due to things like bad grounds. I suppose you may ask the electrical provider that serves that customer if they have and can check the grounds.

 

[MBPoolGuy]

It is an outdoor residential pool at a single family dwelling. It is built inside a 10 ft raised concrete structure set on concrete pillars ( see attached ).
It will have low voltage LED lighting with a gfci breaker.
the 2 pumps will also be on gfci breakers.
I am just not sure if there is an argument that can be made as to this being an exception to the code given it is not in the ground, it is not tied / connected to the support structure steel and the deck surface is insulated from the the ground.
Thanks

 

[ajw22]

Interesting residential pool.

Only the inspectors in your jurisdiction can say what they will accept.

The purpose of bonding is to keep all conductive surfaces that a person can touch around a pool at the same equipotential. The concrete structure can conduct stray voltages up to the pool structure and you can't prove that the pool is insulated now and will stay insulated for the future when things are wet.

There is safety and there is meeting local codes. For safety you should talk to a qualified eletrician like Mike Holt. For meeting local codes it is up to the inpectors.

 

[MBPoolGuy]

Thanks