Grounding and stray voltages....

Status
Not open for further replies.
M

MrHandy2005

Member
We have installed a new 200 amp service in my son's shop.
While I was wiring up some of the outlet boxes(metal), I noticed a slight 'tingle'. The floor is concrete, 10" thick and a bit damp. When I went back to the service entrance, I measured between the earth ground (2-8' copper ground rods, 10 feet apart) and the concrete floor and read a voltage of 1.995 volts AC. I could not read nor detect any current flow.
My question is this- Is this a potential hazard and what would either cause this or what would I need to do to remedy this situation? The building is a steel building and I have grounded the frame of the building. Will bonding the frame of the building to the concrete floor clear this problem? I have no way of getting to the reinforcing mesh without a lot of work.
Thanks,,,,,,
BTW- everything is run in 3/4 EMT
 
Just curious. Is this building fed from another building? In other words, is the panelboard re-grounded at this "additional" building. Maybe there's a metallic path from the main building to this building and the bonding jumper is installed which re-grounds the neutral and perhaps there's neutral current returning and you're feeling that....?:smile:
 
This is likely the voltage drop on the utility primary neutral. This voltage drop raises the voltage on the secondary neutral and everything connected to it with respect to "remote" earth. (earth that is away from any grounding electrode. In you case if the concrete reinforcing is not bonded, the concrete can be the remote earth. The only way to get rid of this voltage is to raise the voltage of the concrete by bonding the reinforcement.
Don
 
I would not expect you to feel that voltage unless it is on your teet.
Is your shop located under high tension wires or a stones throw from a high power RF antenna?
Does the shock dissipate or continue as long as you are in contact?

The PoCo can be helpful in investigating neutral/ground problems at neighbors services and transformers.
 
The "tingle" dissipates,,,and to describe it,,,,if you barely touch the boxes,,,,and like I stated , the floor was quite damp.....
 
I believe I found the problem.....

I believe I found the problem.....

There is a secondary box in the old section of the shop that I tied in to use the existing wiring until this new wiring is all done. The neutral in the secondary box IS bonded to ground. Whomever installed that box has both neutrals and grounds going to the same point in the box on the busses.
I will remedy that and then check the results. The first thin I will do is kill the feed to that box.
Sometimes these things are right in our face and we don't see it!!!
 
I was alluding to the well documented phenomena in which bovine exhibit hypersensitivity to small AC voltages, particularly in milking parlors, that humans appear immune to and generally are oblivious that the voltage exist at all.

I was curious about the voltage sensation dissipating because that is what RF/induced voltages feel like when you touch them. They generally have no ?power? behind them and your body quickly equalizes the potentials. I was GUESING that perhaps a neutral/ground problem would feel more constant. Probably a dumb guess but my only experience is when it knocks you on your rear. All right?I admit, sometimes voltmeters and ammeters are better then your sense of touch
 
Status
Not open for further replies.
Top