"magically grounded" the most important wire in the panel

[wyreman]

Yes, kwired, I liked your image of
"having a hole in that system "
where there would be touch potential for voltage gradients

to restate:
voltage gradients between

the "hole in the system" namely the bolted yet unpowered lift [which I likened to a ground rod]
and the bonding grid​

could have their origin from neutral problems which directly effect the EGC or
smaller, high impedance faults at utilization equipment

and that a person in the non electric lift
could become a pathway between the lower impedance found at the bolting of the lift in the concrete
and the grid
when he was lowered in the water

 

[ritelec]

Yes, kwired, I liked your image of
"having a hole in that system "

??? ha ha ha ha........ I must have been at a different meeting.

to restate:
voltage gradients between

the "hole in the system" namely the bolted yet unpowered lift [which I likened to a ground rod]
and the bonding grid​

ha ha ha sorry...

Don't defend anything or stress anything...

Why are you trying to be the hero... tell them... I don't believe what your asking me to do is right and I am not going to do it...to do it themselves or get someone else..

Don't get involved with the "sit potential" and alike...

 

[wyreman]

family fotos

family fotos

Where did you get that picture of me?
:lol:

 

[wyreman]

They are having a "work speedup" here and the old boss knew everything.
I mean really, that guy has forgot more stuff than I ever knew.
I could rely on him 100%

The new guy wants always "more for less"
They were thinking it was needed because of "static electricity"

I started out quoting chapter and verse

NEC Section 680.26, paragraph 3
"All metal fittings within or attached to the pool structure shall be bonded.​

but I had two shortcomings [that I know of in this case]:

hadn't considered the loose neutral being the worse case -
only thought of leakage from bonded equipment not large enough to trip GFI or CB

Also
hadn't considered the VD to the main on the ground if I wanted to pick up the grid else where.

Opened up the prints now and structural detail calls for 8" slab! with rebar 18" OC so concrete guy is now more willing to dig further =)

 

[PatM]

Thanks very much for the big description on bonding, we've been having a nice discussion about that here (municipality where I maintain 11 pool in four facilities). We've always observed the bonding regs because they're regs, not because we actually understood.

I do have one conceptual problem dealing with pumps or other equipment not actually in the pool chamber. Some pumps in older buildings have bonding wires out in the open which disappear into the concrete floor while other pumps in newer buildings have no obvious bonding wires (though I guess the mounting frame could have a wire attached from the bottom and disappear into the concrete - though it seems pretty unlikely).

Do these pumps require bonding? There's no possibility of a swimmer touching them while in the water but there's probably 80 ways power from the motors could get to the pool tank. If somehow power did get to the water would it be capable of causing a harmful condition? The water is in the tank and the tank is true ground. Intuitively I'd say yes, bond the thing, but I couldn't explain why in any sensible way. Is grounding good enough?

 

[hurk27]

Thanks very much for the big description on bonding, we've been having a nice discussion about that here (municipality where I maintain 11 pool in four facilities). We've always observed the bonding regs because they're regs, not because we actually understood.

I do have one conceptual problem dealing with pumps or other equipment not actually in the pool chamber. Some pumps in older buildings have bonding wires out in the open which disappear into the concrete floor while other pumps in newer buildings have no obvious bonding wires (though I guess the mounting frame could have a wire attached from the bottom and disappear into the concrete - though it seems pretty unlikely).

Do these pumps require bonding? There's no possibility of a swimmer touching them while in the water but there's probably 80 ways power from the motors could get to the pool tank. If somehow power did get to the water would it be capable of causing a harmful condition? The water is in the tank and the tank is true ground. Intuitively I'd say yes, bond the thing, but I couldn't explain why in any sensible way. Is grounding good enough?

The problem with the pumps is that unless they are of the double insulated types the shaft of the motor is still in contact with the circulating water, with the chemicals we had to pools to keep the water clear can also cause the water to be conductive, if these are salt water tanks then this is even more a problem, so yes it is possible that the water it's self could become energized above the rest of the EPB system and you could have a difference of potential, this is why in 2008 the NEC even added a requirement to bond the water by having a plate that is in contact with the water if no other equipment already does this:

680.26(C) Pool Water. An intentional bond of a minimum conductive
surface area of 5806 mm2 (9 in.2) shall be installed
in contact with the pool water. This bond shall be permitted
to consist of parts that are required to be bonded in
680.26(B).

So yes they do conceder that the water is conductive, this is why electrically supplied equipment that makes contact with the circulating water has always been required to be bonded to the EPB system, if it is not part of the water circulating system then 680.26(B)(7) exception 2 allows anything over 5' from the water inside the pool to be exempt from being bonded to this EPB system, but metal parts of electrical equipment associated with the pool water circulating system, has to be bonded no matter where they are as there are no exceptions to the rule in 680.26(B)(6)

Now how to go about doing this after everything is already done? that it the art of being an electrician, we sometimes have to work miracles.

I'm not totally sure when the EPB system requirement was put into the code my 1999 has it in 680-22 but I do believe it wasn't long before that when it was introduced as I remember discussing it at our IAEI chapter meetings, so either 1993 or 1996 update I think maybe someone else could chime in if they know the edition when it was put into the code, I remember prior to that all we were required to do was EGC's to the equipment, so if this is an older installation you might have an out but speak with you city attorney to be sure if liability can be brought in if this could be considered a extreme danger, I think that the EGC of the circuit for the pump will offer protection as long as there is also another EGC that makes connection to the EPB system, or someone mistakingly ran it back to the panel, if they did that then you might be able to extend it to the pumps if you have enough room in the conduits for a #8, but as we know this would not meet the code (using the EGC) as written today, extending the EPB conductor if it was ran to the panel would in my opinion.

I know as electricians we inherit the mess of others sometimes and it can be hard to deal with but, loose one life especially a child, and doing it the right way will always be the best way and allot easier to live with then knowing that we could have prevented a death, harsh I know but it's the truth.

 

[wyreman]

why cant we all just work together - hold hands and sing kum ba yah

why cant we all just work together - hold hands and sing kum ba yah

Concrete guy still hasn't found the rebar on 18" centers
Seems like it is only on the drawings.
Concrete guy did find 6 inch square wire mesh

One electrician here has stated strongly that

he can attach the ground bond to the wire mesh.​

management likes that [more for less and its not really a hazard anyway :/]
and thinks I am being difficult.

To me, wire mesh doesn't have the same area as a #8 bond, but rebar does.

 

[wyreman]

2008 looks like it will be satisfied with the wire mesh

2008 looks like it will be satisfied with the wire mesh

a quick Google search brings this up.
looks like the 2005 NEC needed the rebar
2008 looks like it will be satisfied with the wire mesh

the pool was probably built in 1970!
but the ADA lift chair is going in 2014

NEC 2005, 680.26(C) Equipotential Bonding Grid. The parts specified in 680.26(B) shall be connected to an equipotential bonding grid with a solid copper conductor, insulated, covered, or bare, not smaller than 8 AWG or rigid metal conduit of brass or other identified corrosion-resistant metal conduit. Connection shall be made by exothermic welding or by listed pressure connectors or clamps that are labeled as being suitable for the purpose and are of stainless steel, brass, copper, or copper alloy. The equipotential common bonding grid shall extend under paved walking surfaces for 1 m (3 ft) horizontally beyond the inside walls of the pool and shall be permitted to be any of the following:

(1) Structural Reinforcing Steel. The structural reinforcing steel of a concrete pool where the reinforcing rods are bonded together by the usual steel tie wires or the equivalent (This is not wire mesh
(2) Bolted or Welded Metal Pools. The wall of a bolted or welded metal pool
(3) Alternate Means. This system shall be permitted to be constructed as specified in (a) through (c):
a. Materials and Connections. The grid shall be constructed of minimum 8 AWG bare solid copper conductors. Conductors shall be bonded to each other at all points of crossing. Connections shall be made as required by 680.26(D).
b. Grid Structure. The equipotential bonding grid shall cover the contour of the pool and the pool deck ex-tending 1 m (3 ft)horizontally from the inside walls of the pool. The equipotential bonding grid shall be arranged in a 300 mm (12 in.) by 300 mm (12 in.) network of conductors in a uniformly spaced perpendicular grid pattern with tolerance of 100 mm (4 in.).
c. Securing. The below-grade grid shall be secured within or under the pool and deck media.
You need to know, that this bonding is very important because unless the entire area is brought to the same potential by bonding (hence the name, "equipotential bonding"), then users of the pool are at risk of shock whenever they touch unbonded metallic components of the pool. In addition, the grid is to minimize "step potential" which, as it sounds, is to eliminate the chance that dangerous voltage can travel from one bare foot, through the user's body, out the other foot, due to a difference in potential over a few feet. This is why the grid is required for three feet around the pool.

You might be thinking, 'No big deal, there's no lights or electrical equipment in my pool anyway. I can skip this.' If there is no electrical equipment in the pool itself, you're still not out of the woods, believe it or not. A problem with a local utility company can generate "transient voltages", because the utility uses the earth in their systems too. So a failure of some kind in your service, or your neighbor's service, can result in current passing through the soil in your backyard seeking it's source at the local transformer, or a remote substation, depending on the problem.

People immersed in water are very vulnerable to current, as saturated skin is an excellent conductor.

I'm not blowing smoke, not trying to frighten you, not trying to score a sale. You should find a qualified electrician to help you. A pool is just no small matter.

Read more: http://www.doityourself.com/forum/e...ing-without-rebar-concrete.html#ixzz2wXzWFheM


on the other hand:

As an individual looks at the whole picture associated with this equipotential bonding grid, we have to start to put the requirements together in order to meet the minimum standards of the National Electrical Code. From Article 680.26(C) an individual knows that they have three options to create this equipotential bonding grid system. They also know that whichever equipotential bonding grid system they employ it will have to extend a minimum of three feet horizontally from the inside walls of the pool and under paved walking surfaces. However, what if I do not have any paved walking surfaces. I should have a situation that does not require an equipotential bonding grid system to be installed horizontally 3-foot from the inside walls of the pool.

If method one is used an individual has to extend the reinforcing steel from the contour of the pool to a horizontal distance three feet from the inside wall of the pool. This will allow the equipotential bonding grid to meet the requirements of incorporating the paved walking surfaces within its boundary. If method two (typical pool construction) is employed an individual will have to connect to the walls of a bolted or welded metal pool by a permitted method described in Article 680.26(C). However, an individual will still have to extend 3-feet horizontally from the inside walls of the pool. This is another debated and confusion area within Article 680.26 and is clarified in the 2008 NEC.

The issue is what conductive material does an individual use to construct the equipotetnial bonding grid in these typical pool installations that is required to extend 3 feet horizontally from the inside walls of the pool. If I use the alternative means describe in part three, the bonding grid system is permitted to be constructed as spelled out in (a) through (c). This would mean that I am using a minimum #8 bare solid copper conductor to make my grid and that I have to construct my grid as per (b) and secure it as per (c). This is where the debate comes in. Does an electrical contractor have to use rebar for this 3-foot extension area or can they use wire mesh. What about a #8 equipotential bonding grid ring? The goal is to equal out all the points so that there is no point at a difference within the pool or water area.

As I have mentioned, the 2008 National Electrical Code is further clarifying the explanation of the equipotential bonding grid. At this point the 2005 National Electrical Code has issued a Tentative Interim Amendment (TIA) (05-02 Log No. 821) to handle the problems and concerns associated with Article 680.26(C). This (TIA) will be the new terminology and installation requirement for the equipotetntial bonding grid system. As I have always stated, the wording was incorrect in the 2005 NEC in relationship to the term paved-surface. This is now an exception to Article 680.26(C) that provides the explanation and installation requirements for the 3 foot horizontal equipotential bonding grid under these types of surfaces.

The exception to Article 680.26(C) states ?The equipotential bonding grid shall not be required to be installed under the bottom or vertically along the walls of the vinyl lined polymer walls, fiberglass composite, or other pools constructed of nonconductive materials. Any metal parts of the pool, including metal structural supports, shall be bonded in accordance 680.26(B). For the purposes of this section, poured concrete, pneumatically applied (sprayed) concrete, and concrete block, with painted or plastered coatings, shall be considered conductive materials.? There is also some additional wording that has been added to 680.26(C)(1) that states ?Where deck reinforcing steel is not an integral part of the pool, the deck reinforcing steel shall be bonded to other parts of the bonding grid using a minimum #8 solid copper conductor. Connection shall be made as per 680.26(D).?

New additions to Article 680 are Article 680.26(B)(1)(a) that looks at the requirements of unencapsilated structural reinforcing steel and the fact that it shall be bonded together by steel ties wires or the equivalent.Where structural reinforcing steel is encapsulated in a nonconductive compound, a copper conductor grid shall be installed in accordance with 680.26(B)(1)(b). Article 680.26(B)(1)(b) also states that the copper conductor grid shall be constructed of a minimum #8 solid copper conductors bonded to each other at crossing points. It also requires the grid to conform to the contours of the pool shell and pool deck and shall be arranged in a (12 inch x 12 inch) network pattern with a 4-inch tolerance for spacing.

Article 680.26(B)(2)(b) addresses the perimeter surfaces of the pool area and requires at least one #8 solid copper conductor to be secured within or under these surfaces (18 ? 24) inches measured horizontally from the inside walls of the pool. If this conductor is installed beneath the final grade material, the bonding conductor is required to be buried (6 ? 8) inches below the subgrade. This article also permits the bonding grid to be a single #8 solid copper conductor, wire mesh (547.10(B)), or rebar in the concrete. Article 680.26(C) has added a new twist for bonding the pool water. An intentional bond of a minimum conductive surface area of (9 in2) shall be installed in contact with the pool water.

http://www.kempkeredu.com/articles_read.php?id=5

 

[wyreman]

no mention of wire mesh here! 2011 NEC 1970 swim pool 2014 ADA lift wire mesh bond

no mention of wire mesh here! 2011 NEC 1970 swim pool 2014 ADA lift wire mesh bond

these guys seem to say that mesh is NOT ok in 2011
http://www.harger.com/library/LineCards/Pool Grounding Bonding Line Card.pdf

mike holt seems to agree in 2011
680.26 Equipotential Bonding
no mention of wire mesh here!

http://ewweb.com/electrical-market-101/2011-top-revisions-edition-nec

23
The requirements for swimming pool bonding were revised?again.

680.26(B)(2) Perimeter Surfaces. An equipotential bonding grid must extend 3 ft horizontally beyond the inside walls of a pool, outdoor spa, or outdoor hot tub, including unpaved, paved, and poured concrete surfaces. Perimeter surfaces less than 3 ft that are separated by a permanent wall or building 5 ft in height or more require an equipotential bonding grid on the pool side of the permanent wall or building.

The bonding grid must comply with (a) or (b) and be attached to the conductive pool reinforcing steel at a minimum of four points uniformly spaced around the perimeter of the walls of a pool, outdoor spa, or outdoor hot tub.

Structural Reinforcing Steel. Unencapsulated structural reinforcing steel in concrete shells secured together by steel tie wires [680.26(B)(1)(a)].

Alternative Copper Conductor Grid. Where the structural reinforcing steel isn't available (or is encapsulated in a nonconductive compound, such as epoxy), an equipotential bonding grid meeting all of the following requirements must be installed (Fig. 19):

The bonding grid must be 8 AWG solid copper, arranged in the manner described in 680.26(B)(1)(b)(3).

The bonding grid must follow the contour of the perimeter surface extending 3 ft horizontally beyond the inside walls of pool.

Listed splicing devices must be used.

The grid must be secured in or under the deck or unpaved surface within 4 in. to 6 in. of the underside of the deck.

 

[wyreman]

thats enough for me!

thats enough for me!

So I give up.
I think that rebar is the only way, that or #8 Cu
I don't agree with the wwm woven wire mesh bond
but my co workers have other ideas

here I found one more contradictory that says that in 2008 the mesh was never actually in the NEC, just in the notes =0
and only where the AHJ says its ok

http://www.ecmag.com/section/systems/gone-swimming

Section 680.26(B)(1)(a) requires ?un-encapsulated structural reinforcing steel [steel not epoxy coated] to be bonded together by steel tie wires or the equivalent? wherever the steel crosses each other. Panel 17 deliberately removed the word ?rebar? in the above quoted text to clarify that ?welded wire mesh? is included in ?structural reinforcing steel? but ?only where acceptable to the authority having jurisdiction.? This statement, however, only appears in the panel statement in comment 17-92, not in the NEC. -
See more at: http://www.ecmag.com/section/systems/gone-swimming#sthash.gFQa91Gu.dpuf


enough is enough
I don't like it and I'm on record with that.

 

[wyreman]

http://www.hopewelltwp.org/dca equipotential bonding grid.pdf

2007
Note: It has determined that the deck reinforcing steel (wire mesh) is
acceptable to be utilized for the equipotential bonding grid as per the TIA
and Section 547.10(B) of NEC/2005 which requires the wire mesh to be
bonded to the grid.


\
https://www.mikeholt.com/videodisplaynew.php?pageid=1687

2002nec

(C) Bonding. Equipotential planes must be bonded to the building or structure electrical grounding system. The bonding conductor shall be copper, insulated, covered or bare, and not smaller than 8 AWG. The 8 AWG bonding conductor must terminate to wire mesh or conductive elements of the equipotential plane by pressure connectors or clamps of brass, copper, copper alloy, or an equally substantial approved means.

 

[kwired]

Remember that an equipotential plane and a grounding electrode have different functions, mesh does better accomplish the function of an equipotential plane then a rod does. A grounding electrode is expected to carry current at times, an equipotential plane is supposed to equalize voltage potential across a larger area, but is not necessarily intended to carry any current. Equipment grounding conductors (which the EPB is not) are intended to carry current, only during fault conditions but they are intended to carry current and are sized to be able to handle the current should it happen. An EPB is not an intentional fault current path, it's purpose is to keep potential between objects at a minimal level.

Minimum size of bonding conductors I believe has more to do with physical protection of that bonding conductor more so then it has anything to do current carrying abilities of the conductor. Many instances a small conductor likely would handle the task from a current carrying needs perspective, but a smaller conductor is more subject to being damaged

 

[wyreman]

Well I finally talk to somebody really knows what he's doing then he told me that you don't even know if that wiremesh got bond

Have to check the plans at least see if there was an intention to bomb the bonding detail.

He also told me that in the 70s the rebar was the bond

He also help to educate me about the authority having jurisdiction on smaller improvements and repairs on government work

Seems like up till certain .20 maybe 30 years ago government buildings were built and maintained to higher standard


In belief, man can do anything

 

[kwired]

Well I finally talk to somebody really knows what he's doing then he told me that you don't even know if that wiremesh got bond

Have to check the plans at least see if there was an intention to bomb the bonding detail.

He also told me that in the 70s the rebar was the bond

He also help to educate me about the authority having jurisdiction on smaller improvements and repairs on government work

Seems like up till certain .20 maybe 30 years ago government buildings were built and maintained to higher standard


In belief, man can do anything

My opinion, whether it got bonded or not, sure seems to me like a good idea to bond new items to surrounding items just for the sake of equalizing any potential that could be between them.

 

[wyreman]

So we hired an x-ray company to come in and scan the concrete.
We located the exact location of the rebar.
We cut a little hole access around the rebar so we could get a clamp on it.
Had a trench to the bonding on the chair.
And the job was done in a first-class manner.
The main issue was it was 1000 bucks for the x-ray scanner.
And was it really necessary ?

Anyway I like the outcome and I'm happy



In belief, man can do anything

 

[kwired]

So we hired an x-ray company to come in and scan the concrete.
We located the exact location of the rebar.
We cut a little hole access around the rebar so we could get a clamp on it.
Had a trench to the bonding on the chair.
And the job was done in a first-class manner.
The main issue was it was 1000 bucks for the x-ray scanner.
And was it really necessary ?

Anyway I like the outcome and I'm happy



In belief, man can do anything

Are you asking if it was really necessary to have the x-ray scanner or to do the bonding?

I think it was necessary to do the bonding.

The x-ray scanner - did you save enough time and or save disturbing enough concrete to make up for the cost? I know concrete is kind of high priced compared to in the past but is not like you were likely disturbing too large of an area. If you were disturbing a fairly large area then there must not be much reinforcement in there to begin with, and when I say this I am referring to 50 or even 100 square feet not being considered to be too large, as the difference in cost between the two isn't going to be all that much different when you consider all costs and not just the cost of concrete alone.