grounding and bonding

[petersonra]

I will not reveal the culprit, but I ran into the following situation recently. I thought maybe some of you could help me make the installation code compliant.

A certain customer was convinced by a sales rep that it was necessary to improve their grounding. They went out and bought five 9-foot long ground rods, drilled some holes in their floor, and sank the ground rods into the ground, leaving about a foot exposed. They then added a clamp on the rod, but no wires. Each of these rods is adjacent to columns holding up a crane, that is eventually welded and/or bolted to the building steel.

It would be difficult to convince them to remove the rods, so I am thinking what might be done to make the installation code compliant. It seems to me that all that needs to be done is to run a #6 wire from the ground rod to the steel support beam, which would bond the ground rods to the existing GES, presuming the building structural steel is already properly grounded as part of the GES.

Now if I can only convince them the building steel is not the place to run their EGC to for temporary machine connections, I will have made even more progress. I think their intent was to use the ground rods as a place to connect their EGC to rather than the building steel.

 

[charlie b]

Can't you just tell them to pound the five new rods further into the dirt, then fill in the holes in the concrete, so that they essentially don't exist? The owner can then have a discussion with the sales person, concerning a total refund for an unnecessary sale? You could even suggest that the owner tell the sales person that he can retrieve the ground rods from the ground, if he wishes, before the holes are filled in.

 

[petersonra]

Can't you just tell them to pound the five new rods further into the dirt, then fill in the holes in the concrete, so that they essentially don't exist? The owner can then have a discussion with the sales person, concerning a total refund for an unnecessary sale? You could even suggest that the owner tell the sales person that he can retrieve the ground rods from the ground, if he wishes, before the holes are filled in.

That would have been my first choice, but sometimes you have to have some tact, not something I am real good at. The plant electrician was not thrilled about doing this either, but when someone orders you to do something, and holds your paycheck in his hand...

BTW, the sales rep that convinced them to do this did not sell them the ground rods. I am not entirely sure just how he came to have such influence with them that they would do such a thing.

 

[haskindm]

Treat them as supplementary ground rods. They are not covered by article 250 and may be installed in any manner that they choose. Just do the proper grounding and bonding for the equipment acording to the NEC in addition to these supplementary rods. See 250.54. These are grounding electrodes that are installed because someone does not understand what grounding is.

 

[tom baker]

A study done by the EPRI regaring this type of installation states that is some cases the ground rods contribute more noise to the equipment, as they are not at the same potential as the electrical system grounding.
I consider these time and material electriodes as they are not required and serve no apparent usefull purpose.

 

[1793]

No wires...

No wires...

...and sank the ground rods into the ground, leaving about a foot exposed. They then added a clamp on the rod, but no wires. Each of these rods is adjacent to columns holding up a crane, that is eventually welded and/or bolted to the building steel...

OK, what have I missed? What good are these rods doing installed as stated with no wire(s)?

 

[petersonra]

OK, what have I missed? What good are these rods doing installed as stated with no wire(s)?

A salesman convinced them to do this. Who knows what he had in mind.

My guess is that he wants to use the rod to connect the EGC to.

 

[S'mise]

OK, what have I missed? What good are these rods doing installed as stated with no wire(s)?

The OP says "They then added a clamp on the rod, but no wires. Each of these rods is adjacent to columns holding up a crane, that is eventually welded and/or bolted to the building steel."

Scounds like they plan to bolt the clamp to the colum. ?

Sounds like these supplemental ground rods might be a requirment of the crane manufacture? Thats what hapens when Lawyers do your engineering for you.