electrostatic charges in a water storage tower tank

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cadpoint

cadpoint

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Location
Durham, NC
tom baker said:
No concrete is considered conductive and thats why it can be used as part of a CEE.
Concrete absorbs moisture and holds it, plus it has a lot of ions, all making it conductive.
HG Ufer tested his original concrete foundations done in WWII after 20 years and they still had low resistance in Arizonia
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Concrete cure time is right at 20 years depending on the formula, that's not a fair use of the base line off of Arizona and no rain; is it?

Glass flow's with age so does concrete... the rebar just helps the load along...

:roll:
 
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hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
What two points are they seeing the arc from, are these guys touching two points that can be bonded together? if all the stuff they are touching are connected directly via conductive metal then you might have a case of clothing there wearing? this can be a misconception of being shocked externally. I have found in a few cases where this was a problem where workers wore clothing made of material that built static charges and then when they touched something grounded they felt a shock, if they are standing on a metal ladder or platform that is also connected to the tank, then all parts would be bonded together and they would be at equal potential.

You might want to do an equal potential study to make sure all metal parts have a continuous electrical path between any isolated metal parts, other then that there is no way a person can feel a charge if they are all at the same potential.
 
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Smart $

Smart $

Esteemed Member
Location
Ohio
hurk27 said:
What two points are they seeing the arc from...
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I asked this question, but didn't get an explicit reply :roll:


...if they are standing on a metal ladder or platform that is also connected to the tank, then all parts would be bonded together and they would be at equal potential.
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Perhaps. Perhaps not. Depends heavily on the insulative properties of their footwear.
 
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hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
Smart $ said:
Perhaps. Perhaps not. Depends heavily on the insulative properties of their footwear.
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True but this but this would just support the theory of clothing building a static charge up on the persons body, since nothing electrical or even a static charge could come from just one pathway. I really don't think a static charge could build up on a metal water tower mounted on a concrete base anchored with metal J bolts in the concrete? this misconception also happens with stray voltage, many think the voltage rise is on the Earth when in reality its on the grounding conductors to the equipment that has risen above the Earth potential.
 
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VINSA01

Member
several responses

several responses

Many thanks for your comments

We will proceed as it was stated :

1.- To test static charges (if any) in several parts of the tank. Also the FOP test

2.- To fix the electric wiring accordingly with NEC code or equivalent.

3.- To test again looking for static charges

4.- Based on the foundation drawing , review grounding as far as lightning ( NFPA 780 or equivalent)

About grafite an cadweld I mentioned "it has nothing to do" . I was meaning the GEM or powder of gafite use to enhance electric contact to ground

Thanks again
 
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hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
Generally these static lines run for miles atop the towers, and are apparently isolated from the towers themselves as it was mention that if a bond was used between the tower and static line the accident would not have happened. most of the charge on these lines can be from capacitive coupling from the current carrying lines and from solar and wind, I have even witnessed this trying to install a light pole under a set of 500kv lines much father away, if this static line was bonded to the towers which are mounted on concrete bases, I would think this static voltage would have been drained off. this is why I cant seen this kind of voltage building up on a water tower mounted on a concrete base.
 
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