Equipotential grid

[Little Bill]

I saw on one of MH videos that a panel member for the video had a story about bonding a gutter.
He or his electrician were forced by the inspector to bond the gutter on his house to the exp. grid.
He had, I believe, a satellite installer doing an install. When he was on the roof he got shocked when he touched the gutter. Not sure what else he was touching.
The point was why bond something and put voltage on it that no one would be touching to start with.

 

[FionaZuppa]

I saw on one of MH videos that a panel member for the video had a story about bonding a gutter.
He or his electrician were forced by the inspector to bond the gutter on his house to the exp. grid.
He had, I believe, a satellite installer doing an install. When he was on the roof he got shocked when he touched the gutter. Not sure what else he was touching.
The point was why bond something and put voltage on it that no one would be touching to start with.

The code says within X feet.

If he was so concerned then he should have swapped the downspout to vinyl.

The satellite example was a bond grid that was just a grid only, and then something shorted to it thus raising the voltage high enough to get a shock.

If the grid is tied to a good egc and the grid is tied to one or more gnd rods, the grid will always be near zero, and any fault to the grid should throw a ocpd (breaker, gfi, etc).

As well as being a complete waste of time and resources that advice is completely wrong. Ground rods play no role in electrical safety and if you wanted to avoid a shock you would isolate you and your equipment from the ground.

are you sure you want to stick by your statement?

being isolated does not make it safer. being isolated, like standing on a glass block, only makes you the same high voltage as the fault, you then have a probability that you bridge the ckt to zero, and whack, you're dead. if i want to be safe then i'll stand on a copper plate that is tied to earth, so that if stray voltage comes upon the plate, i not getting shocked.

 

[Little Bill]

The code says within X feet.

If he was so concerned then he should have swapped the downspout to vinyl.

The satellite example was a bond grid that was just a grid only, and then something shorted to it thus raising the voltage high enough to get a shock.

If the grid is tied to a good egc and the grid is tied to one or more gnd rods, the grid will always be near zero, and any fault to the grid should throw a ocpd (breaker, gfi, etc).


are you sure you want to stick by your statement?

being isolated does not make it safer. being isolated, like standing on a glass block, only makes you the same high voltage as the fault, you then have a probability that you bridge the ckt to zero, and whack, you're dead. if i want to be safe then i'll stand on a copper plate that is tied to earth, so that if stray voltage comes upon the plate, i not getting shocked.

I'm beginning to think you either own a company or have stock in a company that makes ground rods. For the "umpthteen" time, ground rods have nothing to do with an equipotential grid. Nor does the grid or gnd rods have anything to do with clearing a fault.

 

[kwired]

Not sure why that is hard to understand. If you connect the equipotential bonding to the gutters then you are putting the stray voltage up at the roof and on the gutters. A person working on a conductive ladder leaning against the structure can be 20' or more away from the pool but the gutter may still be energized. Hence, the ladder is grounded to the earth and the gutter has voltage on it. What happens when you touch the gutter? That is my point

What I don't understand is why you would be bonding said gutter unless it or maybe a downspout connected to it is within zone where NEC requires it to be bonded? You asked why bond the gutter - I agree with you, unless a portion of it is within that zone, then you have no choice, and I'm sure you are aware of that also.

You do still have a possible voltage gradient just outside the perimeter of your pool's equipotential bonding - that bonding does stop somewhere on every installation, NEC's first concern is protecting the users of the pool.

 

[infinity]

What I don't understand is why you would be bonding said gutter unless it or maybe a downspout connected to it is within zone where NEC requires it to be bonded? You asked why bond the gutter - I agree with you, unless a portion of it is within that zone, then you have no choice, and I'm sure you are aware of that also.

This all depends on how it's measured. If the gutter is metal and 10' above the ground but only 3' from the edge of the pool doesn't it still requires bonding even if the downspout is nonmetallic?

 

[kwired]

This all depends on how it's measured. If the gutter is metal and 10' above the ground but only 3' from the edge of the pool doesn't it still requires bonding even if the downspout is nonmetallic?

Another thread is debating this- but very possibly yes.

 

[Dennis Alwon]

In my case, I was talking about the downspout which is metallic and carries the stray voltage to the gutters. It is all part of the same system so I called the downspouts gutters.

 

[FionaZuppa]

In my case, I was talking about the downspout which is metallic and carries the stray voltage to the gutters. It is all part of the same system so I called the downspouts gutters.

So replace the connector from leader to gutter with a vinyl piece, or replace down leader with a vinyl one, gutter "problem" solved.

If its a gutter section that has no down leader, and it's within the bonding zone, then just replace the gutter with vinyl. "Problem" solved.

Should we also bond any metal screws that may also be in the bonding "zone"? How about low voltage lighting fixtures that are metal and are within the bonding zone? You gonna clamp a #6 copper to those fixtures? How about a heavy iron outdoor patio table that is in the bonding zone, need to bond that? What about the iron chairs that go around the table?

But then again, the gutters are isolated until you bond them, isnt being isolated a safer thing? Or did i not understand the isolated comment?

 

[blkmagik21]

So replace the connector from leader to gutter with a vinyl piece, or replace down leader with a vinyl one, gutter "problem" solved.

If its a gutter section that has no down leader, and it's within the bonding zone, then just replace the gutter with vinyl. "Problem" solved.

Should we also bond any metal screws that may also be in the bonding "zone"? How about low voltage lighting fixtures that are metal and are within the bonding zone? You gonna clamp a #6 copper to those fixtures? How about a heavy iron outdoor patio table that is in the bonding zone, need to bond that? What about the iron chairs that go around the table?

But then again, the gutters are isolated until you bond them, isnt being isolated a safer thing? Or did i not understand the isolated comment?

First I’d like to point out it’s # 8 copper. Doing the bond with #6 is just shenanigans. Secondly the reason for the bonding grid is to make sure the potential between the water and any metal reachable parts are the same. If something were to dump power into the water you are safe if the potential remains the same. But if they were to touch something metal (even isolated) while in the pool, the would possibly get a shock from differences in potential.

This is the same reason that if there were a downed power line next to you and you were to walk away. The difference in potential from one step to another (step potential) would be enough for the electricity to jump up through your foot and out your other foot. If you’re ever in that situation hopping on one foot away from the downed power line would be your safest option.


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[GoldDigger]

Hopping on two feet, right next to each other has a much lower risk of falling and the spacing will be very close.
Shuffling on two feet (moving each foot less that half a "foot" each time) is the conservative way to go and is, I believe, the official recommendation.
Slow but steady.

Connecting your two shoe soles with a bonding wire is another alternative.

 

[FionaZuppa]

unless its a salt water pool, if power is dumped into the water, you kinda have the same "foot-hop" issue as the downed power line :thumbsup:

all pools should have 2 or more ground rods around it, a bonding grid, grid then tied to rods and the egc. as noted many a time, NEC code needs fixin in many areas.

 

[kwired]

So replace the connector from leader to gutter with a vinyl piece, or replace down leader with a vinyl one, gutter "problem" solved.

If its a gutter section that has no down leader, and it's within the bonding zone, then just replace the gutter with vinyl. "Problem" solved.

Should we also bond any metal screws that may also be in the bonding "zone"? How about low voltage lighting fixtures that are metal and are within the bonding zone? You gonna clamp a #6 copper to those fixtures? How about a heavy iron outdoor patio table that is in the bonding zone, need to bond that? What about the iron chairs that go around the table?

But then again, the gutters are isolated until you bond them, isnt being isolated a safer thing? Or did i not understand the isolated comment?

680.26(B)(5) & (B)(7):

(5)All metal fittings within or attached to the pool structure shall be bonded. Isolated parts that are not over 100 mm (4 in.) in any dimension and do not penetrate into the pool structure more than 25 mm (1 in.) shall not require bonding.

(7)All fixed metal parts shall be bonded including, but not limited to, metal-sheathed cables and raceways, metal piping, metal awnings, metal fences, and metal door and window frames.

5 mentions items in or attached to the pool, 7 doesn't mention in, attached, or anything about proximity - but there is distances and barriers mentioned in the exceptions that follow. 7 also has no mention of the 4 inch minimum dimension.

Metal table, chairs - I'd say if the base is embedded in the concrete, earth, etc. and any part of the item is within the "zone" then yes they need bonded. If portable then no- that would be disqualified from the requirement by the word "attached".

 

[Craigv]

Re: the suggestion to replace the gutter or downspouts with vinyl. How many homeowners or their architects will accept vinyl as an acceptable substitute where seem less gutters or copper gutters are spec'd?

 

[augie47]

Hopping on two feet, right next to each other has a much lower risk of falling and the spacing will be very close.
Shuffling on two feet (moving each foot less that half a "foot" each time) is the conservative way to go and is, I believe, the official recommendation.
Slow but steady.

Connecting your two shoe soles with a bonding wire is another alternative.

:thumbsup:

 

[kwired]

Re: the suggestion to replace the gutter or downspouts with vinyl. How many homeowners or their architects will accept vinyl as an acceptable substitute where seem less gutters or copper gutters are spec'd?

Then it needs to be bonded or somehow located in a place where bonding won't be required.

 

[FionaZuppa]

Then it needs to be bonded or somehow located in a place where bonding won't be required.

a serious Q. does NEC verbiage say anywhere that the egc cannot be a part of the bonding grid? the two typically get tied to each other, and i dont see verbiage that say you cant tie them together if the pump is dbl insulated. so technically, the gutter system can be tied to egc anywhere in some inconspicuous location, a #8 with a lug bolted to the bottom of a down leader.

having the grid tied to egc is good for faults, but not so great for lightning, hence why a few ground rods is useful.

as for spec'ing copper gutter and its in the bonding zone, then the house plans should have had on it egc wire(s) be brought up in the wall to the roof edge so that it can be used to bond the metal gutter(s).

 

[kwired]

a serious Q. does NEC verbiage say anywhere that the egc cannot be a part of the bonding grid? the two typically get tied to each other, and i dont see verbiage that say you cant tie them together if the pump is dbl insulated. so technically, the gutter system can be tied to egc anywhere in some inconspicuous location, a #8 with a lug bolted to the bottom of a down leader.

having the grid tied to egc is good for faults, but not so great for lightning, hence why a few ground rods is useful.

as for spec'ing copper gutter and its in the bonding zone, then the house plans should have had on it egc wire(s) be brought up in the wall to the roof edge so that it can be used to bond the metal gutter(s).

Why do you want to tie an EGC to the gutter?

EPB is it's own network. Any items in that network that also require an EGC, pool pumps or lights are just some common examples, is where an interconnection to the EGC typically comes into play.

 

[blkmagik21]

If you tie it directly to the egc and a fault happens there is a damn good chance the grid in the concrete, the bonded items etc will become the fault path because it’s less resistance then the ground rods. Do you want to be in the pool while a ground fault happens anywhere in the house?


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[Dennis Alwon]

If you tie it directly to the egc and a fault happens there is a damn good chance the grid in the concrete, the bonded items etc will become the fault path because it’s less resistance then the ground rods. Do you want to be in the pool while a ground fault happens anywhere in the house?


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The equipotential bonding is connected to the equipment grounding conductor thru the pump motor or possible thru the light fixture- 120v heads. In either case, the code does require the equipment grounding conductor to be connected to the equipotential bonding. If you have a double insulated pump then you must connect to the equipment grounding conductor somehow. If the pump is not double insulated then you just need to connect to the lug, on the exterior of the pump, which is connected to the equipment grounding conductor.

 

[kwired]

If you tie it directly to the egc and a fault happens there is a damn good chance the grid in the concrete, the bonded items etc will become the fault path because it’s less resistance then the ground rods. Do you want to be in the pool while a ground fault happens anywhere in the house?


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If you are in the pool you are at same potential as everything around you and won't feel a thing. Same goes for if just a few hundred feet away POCO has a 7200 volt line to neutral (same neutral is bonded to the grounded service conductor supplying the house) fault occur in their distribution lines. This is a prime example of why we install equipotential bonding in and around pools - we don't care so much what the voltage to ground is, we care that everything within reach of users of the pool is at same potential.