Concrete Encased Electrode

[petersonra]

I attended a grounding class about 10 years ago, wherein the instructor used an example of a hotel in Chicago that updated its phone system to a PBX. The installers decided to establish a GES around the new phone closet. They did not bond the new GES to the old GES. Lightning hit the service and blew up the phone system. I'm not sure that helps.

But was the cause the failure to bond the two together? I am always suspicious of attempts to blame "bad" grounding for anything.

 

[don_resqcapt19]

Dan,

Notice the black bar running down the left side of the paragraph - ALL of it. That means the ENTIRE paragraph was rewritten in the 2005 Code.

No it doesn't mean that. It did prior to the 2002 code, but starting with the 2002 code, the complete paragraph gets the verticle line even if they only added a comma.
Don

 

[infinity]

Dan,

No it doesn't mean that. It did prior to the 2002 code, but starting with the 2002 code, the complete paragraph gets the verticle line even if they only added a comma.
Don

I wish that my book had those lines since I find them useful. The 2005 NEC Handbook doesn't have any.

 

[dsteves]

But was the cause the failure to bond the two together? I am always suspicious of attempts to blame "bad" grounding for anything.

Yes, Bob, the root cause was the absence of bonding between the two GES's. The absence allowed a significant potential difference to develop between the GES's, and since the PBX was electrically common to both systems, the entire potential drop was imposed across the PBX.


Dan

PS - The author agrees with Don on the vertical bar clarification point.

 

[dsteves]

I wish that my book had those lines since I find them useful. The 2005 NEC Handbook doesn't have any.

Nor do the 2002, 1999 or 1996 handbooks, unfortunately. It seems it was a good choice to buy the Handbook and the Code text together each year...

Dan