Electrical Shock

[mas985]

Sorry to butt in on this one, but having a masters degree in EE myself, last time I checked it did not qualify me to be an electrician. Having said that, it does help to understand electrical theory and with a bit of experience you can do most of what an electrician does. I just don't see the relevance on pointing out you are an EE. In fact, I think I learned more about house wiring and grounding in my shop class in high school.

Also, forgive my arrogance STS but how does one become an EE through just training and not a degree? Technician yes, engineer, I am not so sure.

Now back to the topic. Hsdancer, you mentioned that when you reach out from the pool and step on the pavers you get the shock. Does that mean you are also holding on to a railing? If so, it could mean the railing is not bonded as well. Was it added later?

Regardless of what the code says or does not say, it probably would not hurt anything to try an extra grounding rod near the pad. If it does solve your problem, then the problem is probably with the grounding in the house or power company.

Also, turning off the power in your house does not change the grounding or neutral only shuts off the hot leads so you may not detect it doing this.

[DONNIE]

Don't mean to jump in the middle of your conversation but it sounds like you guys can answer a simple question. I am planning on adding a wood deck, outward from the concrete around my pool. Do I need to ground the deck in any way? Posts will be poured in concrete. Deck may or may not attach to the concrete around the pool.

Donnie

[South_Texas_Sun]

Sorry to butt in on this one, but having a masters degree in EE myself, last time I checked it did not qualify me to be an electrician. Having said that, it does help to understand electrical theory and with a bit of experience you can do most of what an electrician does. I just don't see the relevance on pointing out you are an EE. In fact, I think I learned more about house wiring and grounding in my shop class in high school.

Also, forgive my arrogance STS but how does one become an EE through just training and not a degree? Technician yes, engineer, I am not so sure.

Now back to the topic. Hsdancer, you mentioned that when you reach out from the pool and step on the pavers you get the shock. Does that mean you are also holding on to a railing? If so, it could mean the railing is not bonded as well. Was it added later?

Regardless of what the code says or does not say, it probably would not hurt anything to try an extra grounding rod near the pad. If it does solve your problem, then the problem is probably with the grounding in the house or power company.

Also, turning off the power in your house does not change the grounding or neutral only shuts off the hot leads so you may not detect it doing this.

Devry Institute of Technology BSEE

[mas985]

Devry Institute of Technology BSEE

Ah, I stand corrected.

[mas985]

One thing I never quite did understand is the logic behind bonding the rebar in a concrete deck since all of the rebar is surrounded by a fairly good insulator (concrete). I guess it is in case the rebar comes in contact with other metal that is exposed but I cannot think of any other reason.

Also, I think I remember from one of my power courses that ground, the dirt kind, can and does have changing potential from the house to the power company although they work pretty hard not to have that problem. So it is not inconceivable that the ground near the pool is at a different potential than the ground of the house/pad and both the house and the pool are not at fault.

The source could be from a neighbor's problem or a burried line that has become exposed. One possibility is 12v landscape lighting. It could be close enough to the pool and exposed to the soil to create some potential difference to the bonding wire. One way to confirm this is to test the voltage between ground at the pad and the soil near the pool vs ground at the pad and the grounding rod for the house. Unfortunately, you will need a lot of extra wire to make the runs.

It will certainly take some detective work to find the source.

[JohnT]

One thing I never quite did understand is the logic behind bonding the rebar in a concrete deck since all of the rebar is surrounded by a fairly good insulator (concrete). I guess it is in case the rebar comes in contact with other metal that is exposed but I cannot think of any other reason.

Wet concrete is a pretty good conductor. Connecting the rebar to the bonding grid or putting a bonded metal mesh in the concrete does a fairly good job of connecting the concrete to the bonding system when the concrete is wet.

[mas985]

Wet concrete is a pretty good conductor. Connecting the rebar to the bonding grid or putting a bonded metal mesh in the concrete does a fairly good job of connecting the concrete to the bonding system when the concrete is wet.

I agree that wet concrete is a good conductor on the surface, but when concrete gets wet, I could be wrong but I would not expect the moisture to get all the way down to the rebar which is 2-3" below the surface. The concrete surface is somewhat porous but not as much to allow moisture to get down 2". What I could imagine is that when the concrete cracks it could allow some of the moisture to reach the rebar and then it would make a difference.

[South_Texas_Sun]

I agree that wet concrete is a good conductor on the surface, but when concrete gets wet, I could be wrong but I would not expect the moisture to get all the way down to the rebar which is 2-3" below the surface. The concrete surface is somewhat porous but not as much to allow moisture to get down 2". What I could imagine is that when the concrete cracks it could allow some of the moisture to reach the rebar and then it would make a difference.

Mark, in one of my past "lives" I worked in a government building where they would periodically test the concrete conductivity as an indicator for the corrosion to the rebar embedded in the concrete.

As it turns out, much of the world's population housing and the existance of skyscrapers, bridges, and even nuclear power plants, rests on the natural "miracle" of nearly exact coefficents of thermal expansion between rebar and concrete. Move over, Fibonacci.

But what worried me about ....(shading eyes to avoid embarassing direct eye contact of thread-hijacking complaints)......dsamples VINYL pool problem was that his vinyl liner is possibly masking some greater electrical fault that would normally trip a breaker, but doesn't because of the insulation-to-ground properties of the vinyl liner.

I'm not an electrician, but I would imagine that the newly required NEC "grid" requirements mentioned by John are a response to some poor soul's accidental electrocution by a situation very similar to dsamples current dilemma.

I hope it gets fixed, if only for the peace of mind.

STS