Pool bonding question

[don_resqcapt19]

the earth rods are there to direct any surface or under surface voltage into the ground. large joules that travel across the surface and into the bonding (w/o rods) may/can wreak havoc on the items connected to the bonding. the rods only help to divert the joules into the ground.

equipotential bonding vs bonded to gnd (w/ earth rods), thats how i see it, and i like the latter better.

Grounding electrodes only work as a shock control device by raising the voltage of the earth around the grounding electrode to that of the bonding conductor. If you are more than 5' from the rod, they have almost no effect on reducing the shock hazard.

The pool bonding is intended to keep everything at the pool at the same potential. This will often be a potential that is above "earth" and that is why, in addition to the water and all of the pool equipment, the code requires the perimeter surface around the pool to also be bonded.

 

[FionaZuppa]

earth rods are there to help direct surface or under surface energy, i like joules units. with a lightning strike 50m away its very possible for that to traverse the surface looking for ez path, this is where earth rods help. rods can also "help" in the case where your service gnd decides to go high ohms.

as far as "equi-pot", taking it to service gnd in disco clamps it somewhere between service gnd and earth while still being equi-bonded. i'd rather be at gnd then at some unknown high voltage. shorting 120v to a simple equi-bond should (should) trip gfi, but if it doesnt then you are still at risk for bridging a potential diff, more risk as you get near the edge/perimeter of the bonding.

 

[don_resqcapt19]

earth rods are there to help direct surface or under surface energy, i like joules units. with a lightning strike 50m away its very possible for that to traverse the surface looking for ez path, this is where earth rods help. rods can also "help" in the case where your service gnd decides to go high ohms.

It may provided some protection for lighting (but no one should be in the pool if there is lightning anywhere nearby), but it will not provide any shock protection for an open neutral, unless you are standing on or very close to the ground rod.

as far as "equi-pot", taking it to service gnd in disco clamps it somewhere between service gnd and earth while still being equi-bonded. i'd rather be at gnd then at some unknown high voltage. shorting 120v to a simple equi-bond should (should) trip gfi, but if it doesnt then you are still at risk for bridging a potential diff, more risk as you get near the edge/perimeter of the bonding.

Unless you have an actual fault of an ungrounded conductor, the equipotential bonding puts you at the same voltage as the service ground. You are directly bonded to the service ground and the only thing that will change the potential is a voltage drop in the bonding conductors.

The problem with being at ground potential is that is not possible unless there is no electrical equipment or bonding connections for the pool, perimeter surface and pool water. The service ground will almost always be at an elevated voltage as compared to "remote earth" (earth outside the influence of any electrical system grounding electrode, often specified as 50' away). The bonding connections put everything associated with the pool at this elevated potential.

 

[keith gigabyte]

bonding

bonding

I have done a handful of pools; the water bond is something new to me. I have done the "ring" around the pool and bonded at pump lug; bonded stanchons.

Some inspectors require ground rod. I think it compromises the desired bond function of above items. Are we not trying to get pool metal and water at the same ground reference as the circuit ground feeding equipment?
Also should the ring be connected to the ECG from the panel? Example: above ground pool with ONLY pump. Pool located 25 feet from house. Feed with PVC conduit 12 awg thwn GFCI branch circuit breaker in panel at house. FSE box with twist lock outlet to service pool pump.
seems a little mismatched 12AWG circuit ground and #8 ground ring.

Input?

 

[Little Bill]

I have done a handful of pools; the water bond is something new to me. I have done the "ring" around the pool and bonded at pump lug; bonded stanchons.

Some inspectors require ground rod. I think it compromises the desired bond function of above items. Are we not trying to get pool metal and water at the same ground reference as the circuit ground feeding equipment?
Also should the ring be connected to the ECG from the panel? Example: above ground pool with ONLY pump. Pool located 25 feet from house. Feed with PVC conduit 12 awg thwn GFCI branch circuit breaker in panel at house. FSE box with twist lock outlet to service pool pump.
seems a little mismatched 12AWG circuit ground and #8 ground ring.

Input?

The inspectors are wrong unless there is a local amendment. Even if they do have an amendment it doesn't help anything to add ground rods. It's already been explained in the previous posts.

No, it's not required to connect the bond wire/ring to the EGC at the panel (main or sub)
The bonding lug on the pump motor will inadvertently connect the bonding grid/ring to the system EGC provided that the motor was properly grounded by running an EGC with the circuit conductors and connecting it to the grounding terminal in the motor. The bond around the pool is NOT for fault current to trip a breaker.
That's what the EGC is for. As explained, the bond is to bring everything in and around the pool to the same potential.

 

[FionaZuppa]

saying earth rods are useless is silly.
very dry climates usually have high omhs at the surface.
adding 10ft earth rod can help keep surface stray/fault voltage tied into wet/moist earth (when tied to a bonding system).
lets say you are out 50-100ft with a disco/breaker sub, bang in a rod there and tie egc to the rod.
next, build your bonding system and then tie that to the rod you have at the disco/breaker sub.
as stated, this can also help if say the egc on pump lug corrodes off or egc at the pool is lost for any reason.

in NEC world, dont have to, but for the extra few $$ for a rod, you get some benefits.

 

[don_resqcapt19]

saying earth rods are useless is silly.
very dry climates usually have high omhs at the surface.
adding 10ft earth rod can help keep surface stray/fault voltage tied into wet/moist earth (when tied to a bonding system).
lets say you are out 50-100ft with a disco/breaker sub, bang in a rod there and tie egc to the rod.
next, build your bonding system and then tie that to the rod you have at the disco/breaker sub.
as stated, this can also help if say the egc on pump lug corrodes off or egc at the pool is lost for any reason.

in NEC world, dont have to, but for the extra few $$ for a rod, you get some benefits.

I really fail to understand how raising the voltage of the earth around the ground rod provides any additional benefit over the code required equal potential bonding system. The only thing we are trying to do here is to keep everything in the pool area at the same voltage so there is no potential differences. No matter how many rods we drive, we do not change that voltage, we just raise a small area around the rods to the voltage of the electrical grounding system.

 

[FionaZuppa]

I really fail to understand how raising the voltage of the earth around the ground rod provides any additional benefit over the code required equal potential bonding system. The only thing we are trying to do here is to keep everything in the pool area at the same voltage so there is no potential differences. No matter how many rods we drive, we do not change that voltage, we just raise a small area around the rods to the voltage of the electrical grounding system.

if you bond to egc (and earth), what potential would the bonded system ever get to?

lets say its a pool deck, concrete, has all the required bonded stuff, and not tied to anything else. the concrete and ground around the decking is all wet from kids playing all day. the bonded system suddenly becomes 240vac for whatever reason. there is no potential between bonded items ("safe"), but now a wet kid has one foot on decking and another foot in the wet dirt. you see a hazard there ??

if everything is tied to egc/earth, you get two things, 1) possible fault path, gfi trips, 2) the voltage on the bonded system is earth potential, nearly zero.

 

[don_resqcapt19]

...
lets say its a pool deck, concrete, has all the required bonded stuff, and not tied to anything else.

The code does not permit that. The bonding is required to be connected to the EGC(s) that serve the pool equipment.

the concrete and ground around the decking is all wet from kids playing all day. the bonded system suddenly becomes 240vac for whatever reason. there is no potential between bonded items ("safe"), but now a wet kid has one foot on decking and another foot in the wet dirt. you see a hazard there ??
..

Sure there is a hazard there, but adding ground rods does not reduce the hazard. All the ground rods would do is energize a small area of earth around the rod. The grounds rod does not get rid of the voltage. The only thing that can do that is to clear the fault.

 

[FionaZuppa]

oi. if for whatever reason the egc at the pool gear goes south. having a separate tie from bonding over to sub panel provides the extra assurance. i have many times for many reasons seen egc copper at pool gear broken or useless. stab the earth with a ground rod at the sub, tie the egc and bond grid to the rod. done.

and no, a 10ft ground rod will not be like a short piece of copper/bronze connected to another 9ft of insulator!

 

[GoldDigger]

oi. if for whatever reason the egc at the pool gear goes south. having a separate tie from bonding over to sub panel provides the extra assurance. i have many times for many reasons seen egc copper at pool gear broken or useless. stab the earth with a ground rod at the sub, tie the egc and bond grid to the rod. done.

and no, a 10ft ground rod will not be like a short piece of copper/bronze connected to another 9ft of insulator!

The ground rod kludge that you describe would be directly against code and would not necessarily provide a sufficient fault current path if the neutral became impaired.

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[FionaZuppa]

The ground rod kludge that you describe would be directly against code and would not necessarily provide a sufficient fault current path if the neutral became impaired.

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and neither would a broken egc at the pool gear, right?

against code? please share.
from what i read, "...shall not be required...", which means "optional".
direct from the NEC code "the equipotential bonding required by this section shall be installed to reduce voltage gradients in the pool area"

 

[GoldDigger]

Could you be more specific about where it is stated that a connection of an EGC to the pool equipment is optional?

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[ActionDave]

saying earth rods are useful is silly.....

Fixed it for you.

 

[FionaZuppa]

Could you be more specific about where it is stated that a connection of an EGC to the pool equipment is optional?

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i didnt say egc to pool gear, i said the bonded grid to egc.
680.26(B)

 

[GoldDigger]

i didnt say egc to pool gear, i said the bonded grid to egc.
680.26(B)

As a practical matter at least one of the elements in the grid also requires an EGC. So if the EGC is damaged, I don't see how you can avoid repairing or replacing it.
But maybe I am not understanding your hypothetical situation.

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[petersonra]

Since those screws are short I replaced it with a longer sheet metal screw. Is that ok?

are you allowed to use sheet metal screws at all? I think it probably should be a machine screw.

 

[Dennis Alwon]

At this point, I don't even know what is being argued but the epb must be connected to the egc somewhere in the system. Normally a pool pump has a bonding lug on the outside that is connected indirectly o the egc however in a situation of a double insulated pump the epb needs to connected to the egc directly.

(6) Electrical Equipment. Metal parts of electrical equipment
associated with the pool water circulating system, including
pump motors and metal parts of equipment associated with
pool covers, including electric motors, shall be bonded.
Exception: Metal parts of listed equipment incorporating an approved
system of double insulation shall not be bonded.


(a) Double-Insulated Water Pump Motors. Where a double insulated
water pump motor is installed under the provisions of
this rule, a solid 8 AWG copper conductor of sufficient length
to make a bonding connection to a replacement motor shall be
extended from the bonding grid to an accessible point in the
vicinity of the pool pump motor. Where there is no connection
between the swimming pool bonding grid and the equipment
grounding system for the premises, this bonding conductor
shall be connected to the equipment grounding conductor of
the motor circuit.

 

[FionaZuppa]

As a practical matter at least one of the elements in the grid also requires an EGC. So if the EGC is damaged, I don't see how you can avoid repairing or replacing it.
But maybe I am not understanding your hypothetical situation.

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the egc is carried over from the panel/sub to the pool gear, its there at the pool gear many take the bonding to, and its there where the egc can become problematic. thats an ok method, i am just saying, stab a 10-20ft rod in near sub panel, tie the sub panel box (or egc lug) to the rod, then carry over from the bond grid a #6 bare copper and clamp it to the rod. pool gear is subject to corrosive chemicals, and when there is an egc issue it often goes unseen.

will you get an ocpd trip via the ground rod, probably not, but at least it will help if the egc at sub becomes broken, the fault current in rod is enough to cause gfi to trip. would a gfi trip if egc is lost and bond grid became 240vac and a swimmer parallels the ckt, maybe gfi trips, but the rod has a better chance of allowing more than gfi trip amps.

and when i say the rod helps to bring down the bond potential, it usually does because voltage shorts to places where we dont want it is usually through a high ohms bridge (corroding wire that for whatever reason touches bond grid).

when freshly installed per NEC it should all work ok. i am suggesting an additional step.

its a ground rod with small amount of extra copper and perhaps a few clamps. makes for a overall safer setup when you factor in pool use and time.

 

[Dennis Alwon]

If we install a panel remote from the dwelling wouldn't we have to install ground rods for the panel? It is a separate structure, IMO so rods or ges would be required