Ground Ring

[buddy91082]

Attached is a very rough sketch of a simple oneline grounding scheme of two buildings.

Building #2 is served from Building #1.

My concern is the ground ring at Building #2. The installation has the ground ring at Building #2 back to the groudn bar in the distribution panel at building #2. The bare copper conductor for the groudn ring is routed to the distribution panel and bonded to the distribution board enclosure and terminates at the ground bar. The ground ring at Building #2 is also connected into the lightning protection system for Building #2.

When i saw the bare copper ground ring bonded to the distribution board enclosure my spidey sense kicked in.

If anyone has any refernce is this is code compliant I'm all ears. I'm not looking for opinions; just want to know if it's right or wrong.

thanks.
b

 

[resqcapt19]

That appears to be exactly what is required for a second building by the 2008 NEC. 250.32(A) requires a grounding electrode at the second building. The ground ring, assuming it was installed per 250.53(F) is the required grounding electrode. 250.32(B) requires that an equipment grounding conductor be run with the feeder conductors and be connected to the building disconnect enclosure and to the building grounding electrode. I don't have the section, but NFPA 780, the Lightning protection code, requires that the electrical grounding electrode and the lighting groundind electrode be bonded together.

 

[resqcapt19]

Taking a second look, it looks like the ground ring is the lighting protection grounding electrode. If that is the case a grounding electrode for the electrical system will be required. I don't know how big, or what type of construction the second building is, but starting with the 2005 NEC, if the footing or foundation had 20' or more of #4 or larger re-bar, you are required to use the re-bar as a grounding electrode and that could be the electrical system grounding electrode.

 

[buddy91082]

Thanks resqcapt19.

I forgot to put in the one line that incoming water pipes (which also originate at building #1) are used as the grounding electrodes for building #2.

So it's ok to have the bare coper conductor (uninsulated) for the ground ring at building #2 to be installed through the distribution board enclosure? I would have thought it would need to be insulated when in the distribution board enclosure.

thanks
b

 

[jghrist]

NEC Article 250.50 requires all grounding electrodes to be bonded together.

 

[rbulsara]

The sketch looks OK to me, code wise.

 

[resqcapt19]

I see no issue with the bare conductor in the panel. It is common to run a bare grounding electrode conductor in a panel and with some wiring methods the equipment grounding conductor is bare.