petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Storage trailer grounding
- Thread starter gsurace
- Start date
- Status
RichB
Senior Member
- Location
- Tacoma, Wa
- Occupation
- Electrician/Electrical Inspector
Correct--sort of--
What I am seeing and what I am finding during research into this is----When most of these installations were done (10, 20 30+ years ago) the RMC and poles were bonded together, relying on the RMC as the EGC and not pulling in a ( at the time"redundant") ground/bond of the wire type--The RMC corroded and the low impedance path was consequently lost---Resulting in the dangerouos and life threatening situations we now have.
I was sure that's what you meant. I was just clarifying.
The metal conduit is an acceptable means of a ground return path, just like the EGC in the cord that the
OP has installed. If the return path was to fail in either of these instances,a driven ground rod attached
to the structure would be of no help to clear a ground fault due to to the high resistance of the earth.
That is unless the resistance between the driven ground rod and source was low enough for a high enough
current to flow and trip the breaker. Which I have yet to witness.
Yes it does, but your talking about a failed return path not a properly working return path that is bonded to
the pole.
- Location
- Illinois
- Occupation
- retired electrician
Most of the cases like this that I have read about were installed by utilities using the NESC and not the NEC. The NESC does not require an EGC.
- Location
- Illinois
- Occupation
- retired electrician
The key here is "nearby earth". You would be subjected to ~85% of the voltage if you are touching the trailer and standing on the earth 3' from the ground rod. At 5' you would have almost 100% of the voltage.
I know someone based those numbers on empirical tests... but I believe that depends on the conductivity of the earth at whatever location it occurs, and not all areas are the same. But the implied principle is correct... that's why I mentioned the grounding grid (equipotential grounding plane). Say someone went to the degree of covering the entire earth in the area with sheet steel and bonded it to the trailer. That would be an example taken to the extreme :happyyes:
Additionally, as I stated earlier that many factors are involved, the person's body is not necessarily subjected to full voltage. It depends also on what they are wearing at the time. If standing and wearing highly insulative shoes, they may not even feel a tingle.
- Location
- Massachusetts
- Location
- Massachusetts
Of course, but it takes very little conductivity to feel it and not much more to hurt you.
- Location
- Massachusetts
Dig a little deeper... (hint: see definition of the terminology used in my post)
RichB
Senior Member
- Location
- Tacoma, Wa
- Occupation
- Electrician/Electrical Inspector
Correect again!! You win a cookie!! :thumbsup: What movie is that quote from??
Anyway--The 2 areas I have been involved in are under the NEC and the systems are all at least 20 years old here in Seattle and that is what I am baseing my observations on for the purpose of this discussion. WHeew that's a long winded way of saying something>
Anyway--Love the discussion and as always I learn something from all of you everyday
Thanks!!
- Location
- Massachusetts
Does not change my opinion.
What we work with are not designed to be hooked up by anyone but an electrian. IMO that article does not apply to what the OP is describing.
As much as I value your opinion, I think I'll go with this one...
- Status