Stray Voltage

[Sea Nile]

If you have a sufficiently bonded structure, everyone inside that structure would be protected from the problems described in the original post, just like swimmers in a properly bonded pool.

This would probably mean bonding all of the rebar in the slab and footing, not just a ground ring.

I agree. The problem is I think that they may not have rebar throughout the whole slab due to what the electrician said

"Electrician #2 came out and disagreed with #1 and said that its a slab bonding issue. He couldn't recommend anything (short of tearing out concrete) and pointed me to this forum for pointers."

So I don't know the solution and am thinking outside the box

 

[don_resqcapt19]

My understanding of a ground rod is that the only purpose it serves is to bleed off induced voltage from nearby lightning strikes. Other than that, they have no purpose whatsoever.

But after watching every swimming pool video that Mr. Holt has on his site,. My understanding of having an electrode encased shell will protect swimmers from NEV.

That's why I suggested a ground ring around the house installed exactly the same way a pool would be installed.

I know many will tell me it's pointless and I accept that, but I'm just brain storming here.

Pools require bonding and not grounding. The bonding raises everything in the pool to the voltage that shows up between the electrical grounding system as a result of NEC and earth that is remote from any grounding electrode. Special bonding is required for pools because the few volts of NEC can be a very serious issue for someone in the pool water.

Your ground ring would work, but only if you are standing on the ground within a foot or two of the ground ring. Just as with a pool, that would serve to raise the voltage of a small area of earth around the ground ring to NEV.

 

[paulengr]

Nonsense on testing utility grounds or homeowner grounds.

The best method is a 3 point ground tester. You connect to a ground rod and two reference stakes placed strategic distances away (usually it works out to around 100 feet). A pole ground is totally accessible and very obvious. You will see a single bare copper wire stapled to the pole running down it. It is wrapped several times around the pole butt then buried. Nothing else looks like it. It will be connected to the neutral/ground.

 

[Sea Nile]

Pools require bonding and not grounding. The bonding raises everything in the pool to the voltage that shows up between the electrical grounding system as a result of NEC and earth that is remote from any grounding electrode. Special bonding is required for pools because the few volts of NEC can be a very serious issue for someone in the pool water.

Your ground ring would work, but only if you are standing on the ground within a foot or two of the ground ring. Just as with a pool, that would serve to raise the voltage of a small area of earth around the ground ring to NEV.

That's what I wasn't sure about. I didn't know if the center of the ring would revert back to remote earth NEV or would the ring divert the NEV around the structure.

I guess the home owner is up the creek.

As far as pools not requiring grounding, I think a concrete encased web of rebar pretty much automatically grounds the pool.

 

[GoldDigger]

Pools require bonding and not grounding. The bonding raises everything in the pool to the voltage that shows up between the electrical grounding system as a result of NEC and earth that is remote from any grounding electrode. Special bonding is required for pools because the few volts of NEC can be a very serious issue for someone in the pool water.

Your ground ring would work, but only if you are standing on the ground within a foot or two of the ground ring. Just as with a pool, that would serve to raise the voltage of a small area of earth around the ground ring to NEV.

If the NEV potential is large enough, all that complete pool bonding according to code will do is transfer the hazard from touch potential for people in the pool to step potential for people walking toward or away from it. Unless a potential ramp is included in the design.

 

[Sea Nile]

If the NEV potential is large enough, all that complete pool bonding according to code will do is transfer the hazard from touch potential for people in the pool to step potential for people walking toward or away from it. Unless a potential ramp is included in the design.

Potential ramps are cool and an ingenious way to keep cattle from getting zapped when entering a grounded building located far away from the substation.
My only goal was figuring out a way to equalize the potential between the kitchen floor and the kitchen appliances without destroying anything or costing a lot of money.
Not concerned with the step potential outside the home. That can only be solved when the problem causing the issue is identified. (POCO, neighbor, or distance from sub station)
If a ground ring can't do that, then I'm in agreement with electrician #2. Rip out the concrete floor and fix the issue with the slab bonding.

 

[Fred B]

If the NEV potential is large enough, all that complete pool bonding according to code will do is transfer the hazard from touch potential for people in the pool to step potential for people walking toward or away from it. Unless a potential ramp is included in the design.

Mike did an experiment that realistically showed the safety effect of a proper EP bond. Even 120V introduced into the water the EP allowed for safe egress away from the source voltage by creating exactly what you are referencing that step potential. A potential ramp and EP bonding is also required in a live stock barn and had prove the EP that was throughout the floor of the barn was highly effective for NEV. Studies suggest than milk cows are exceptionally sensitive to NEV and the stress caused by the NEV would reduce milk production and by putting in an EP bonding production increased. Also observing animal hesitancy to enter a barn was found to be related to NEV and led to adding a ramped EP at the barn entry to allow a gradual increase of the step potential to below what the animal would react to. Mike has a good video discussion of this topic.

 

[Fred B]

Potential ramps are cool and an ingenious way to keep cattle from getting zapped when entering a grounded building located far away from the substation.
My only goal was figuring out a way to equalize the potential between the kitchen floor and the kitchen appliances without destroying anything or costing a lot of money.
Not concerned with the step potential outside the home. That can only be solved when the problem causing the issue is identified. (POCO, neighbor, or distance from sub station)
If a ground ring can't do that, then I'm in agreement with electrician #2. Rip out the concrete floor and fix the issue with the slab bonding.

A ground ring is only effective in a very limited distance away from the ring itself as a result of the gradient effect of as you move away from the EP bonding ring.

 

[don_resqcapt19]

Potential ramps are cool and an ingenious way to keep cattle from getting zapped when entering a grounded building located far away from the substation.
My only goal was figuring out a way to equalize the potential between the kitchen floor and the kitchen appliances without destroying anything or costing a lot of money.
Not concerned with the step potential outside the home. That can only be solved when the problem causing the issue is identified. (POCO, neighbor, or distance from sub station)
If a ground ring can't do that, then I'm in agreement with electrician #2. Rip out the concrete floor and fix the issue with the slab bonding.

That is just covering the problem up...there is a real problem that is creating this potential and it needs to be found and corrected.

 

[Sea Nile]

That is just covering the problem up...there is a real problem that is creating this potential and it needs to be found and corrected.

Last thing I want to suggest, maybe there are two problems. There is the problem somewhere outside of the home that's causing the elevated NEV. And there may be a problem with the slab bonding.

The elephant in the room, I believe, is this:::

If the slab had rebar in it, and it was properly bonded to the same ground rod that is bonded to the panel which had ground wires to all the appliances, then there wouldn't be a difference of potential in the kitchen. The NEV being elevated is probably a problem somewhere outside, but the OP would probably never even know about it if not for the slab problem.

So I disagree that it's just covering up the problem to address it.

But that's all I have to say about that.

 

[retirede]

Last thing I want to suggest, maybe there are two problems. There is the problem somewhere outside of the home that's causing the elevated NEV. And there may be a problem with the slab bonding.

The elephant in the room, I believe, is this:::

If the slab had rebar in it, and it was properly bonded to the same ground rod that is bonded to the panel which had ground wires to all the appliances, then there wouldn't be a difference of potential in the kitchen. The NEV being elevated is probably a problem somewhere outside, but the OP would probably never even know about it if not for the slab problem.

So I disagree that it's just covering up the problem to address it.

But that's all I have to say about that.

There’s no code requirement to bond a slab to anything, so how can it be stated that lack of bonding is a problem that must be addressed?

 

[Gene B]

There’s no code requirement to bond a slab to anything, so how can it be stated that lack of bonding is a problem that must be addressed?

If a homeowner wants to eliminate the experienced NEV (not for safety reasons or milk production reasons, but just because he doesn't like it), then bonding accomplishes that. Complaining to the utility might also work, but they aren't obligated to reduce NEV to zero. Stray voltage is normal as far as utilities are concerned.

(I'm assuming that the problem is NEV...that needs to be confirmed of course).

 

[Fred B]

Last thing I want to suggest, maybe there are two problems. There is the problem somewhere outside of the home that's causing the elevated NEV. And there may be a problem with the slab bonding.

The elephant in the room, I believe, is this:::

If the slab had rebar in it, and it was properly bonded to the same ground rod that is bonded to the panel which had ground wires to all the appliances, then there wouldn't be a difference of potential in the kitchen. The NEV being elevated is probably a problem somewhere outside, but the OP would probably never even know about it if not for the slab problem.

So I disagree that it's just covering up the problem to address it.

But that's all I have to say about that.

There is no requirement that a residential basement floor be made with EP bonding. So labeling that as a problem is not justified. One help to the situation would be to have made in the basement floor an EP bonding, but the cause of the NEV is the problem. Address that to resolution and you have a true fix. Otherwise just adding an EP bond to the basement floor is just covering over the real issue that could actually get worse. Maybe a completely dropped neutral.

Also found a high NEV on a system with buried conductors that one leg was damaged and was bleeding current into the ground, once we replaced the damaged conductors the NEV disappeared. (One GE was within 10 ft of break.)

So the NEV is not something that should be just covered up by having or installing the EP bonding to just get rid of the touch potential. Getting to the source can be critical and in the last case above can save the customer money on the utility bill.

 

[GoldDigger]

There is no requirement that a residential basement floor be made with EP bonding. So labeling that as a problem is not justified. One help to the situation would be to have made in the basement floor an EP bonding, but the cause of the NEV is the problem. Address that to resolution and you have a true fix. Otherwise just adding an EP bond to the basement floor is just covering over the real issue that could actually get worse. Maybe a completely dropped neutral.

Also found a high NEV on a system with buried conductors that one leg was damaged and was bleeding current into the ground, once we replaced the damaged conductors the NEV disappeared. (One GE was within 10 ft of break.)

So the NEV is not something that should be just covered up by having or installing the EP bonding to just get rid of the touch potential. Getting to the source can be critical and in the last case above can save the customer money on the utility bill.

In some cases NEV results from problems with the POCO MGN that they simply are not willing or able to resolve. In those cases a neutral isolator, installed by POCO, can prevent the utility NEV from causing customer problems. Not a true fix, but addresses the symptoms very well.

 

[mike@mikeholt.com]

W

Hello all. First thing first...I'm not an electrician, I'm an first year apprentice. My journeyman has tried and can't get to the bottom of the problem so...I have paid two licensed electricians ~ $1000 to come drive another ground rod and the problem still exist. I have slab foundation. My finished floors are stained concrete. When I'm standing on my floor barefoot and touch my fridge, stove, or any other electrical metal component, I feel it tingle.

Electrician #1 came out and determined that the wiring was sound in the house(new construction). Checked between the fridge and the floor (on a wet paper towel) and got 8 volts. He then started turning off breakers one at a time with not change. He then killed the main at the meter and it remained. He said it was a ground rod issue and drove another ground rod. It reduced the issue but it remained ~5V.

Electrician #2 came out and disagreed with #1 and said that its a slab bonding issue. He couldn't recommend anything (short of tearing out concrete) and pointed me to this forum for pointers.

So I ask, Any ideas?

Note: my slab has rebar but it is not tied to the electrical system/earth at all by a bonding wire. Elect#2 stated that though not required to bond the slab, it is always recommended.

 

[mike@mikeholt.com]

This is Mike Holt, this is called NEV or Neutral to Earth Voltage. Watch my video on this topic at MikeHolt.com/NEV. Everybody has this voltage (NEV), just that few people are aware of this, unless they get shocked at boat docks (MikeHolt.com/Docks) or pools (MikeHolt.com/Pools).

 

[don_resqcapt19]

If the NEV potential is large enough, all that complete pool bonding according to code will do is transfer the hazard from touch potential for people in the pool to step potential for people walking toward or away from it. Unless a potential ramp is included in the design.

But the hazard to people from a step potential is much less than the hazard for a person in the water touching something that is not at the same potential.

 

[Sea Nile]

If the slab was constructed with rebar then I believe it qualifies as an electrode and per 250.50 and should have been bonded. Especially if this was a new build.

"Note: my slab has rebar but it is not tied to the electrical system/earth at all by a bonding wire. Elect#2 stated that though not required to bond the slab, it is always recommended."

Since nothing can be done about NEV, the easiest way to solve this is to chip away some concrete until some rebar is exposed and bond it.

 

[don_resqcapt19]

If the slab was constructed with rebar then I believe it qualifies as an electrode and per 250.50 and should have been bonded. Especially if this was a new build.

"Note: my slab has rebar but it is not tied to the electrical system/earth at all by a bonding wire. Elect#2 stated that though not required to bond the slab, it is always recommended."

Since nothing can be done about NEV, the easiest way to solve this is to chip away some concrete until some rebar is exposed and bond it.

In my opinion, a slab never qualifies as a concrete encased electrode as it is not a footing or a foundation. In addition, the building codes often require a vapor barrier between a slap and the earth and that would disqualify it from being an electrode.

You can force the utility to correct excessive NEV, but it will often require a lot of work and complaints to the state agency that regulates power utilities.

 

[robertd]

If the slab was constructed with rebar then I believe it qualifies as an electrode and per 250.50 and should have been bonded. Especially if this was a new build.

"Note: my slab has rebar but it is not tied to the electrical system/earth at all by a bonding wire. Elect#2 stated that though not required to bond the slab, it is always recommended."

Since nothing can be done about NEV, the easiest way to solve this is to chip away some concrete until some rebar is exposed and bond it.

>chip away some concrete until some rebar is exposed and bond it.
Just make sure you don't have a post tension concrete slab before you start cutting it.