National Electrical Code Articles and Information
| by Mark
A Master Electrician relates this true story:
The electrical services firm I work for sent me to a plant that had all kinds of power quality problems. The "geniuses" there decided to "isolate" the equipment so it wouldn't "pick up noise from ground." So the whole place floated. It took me about three hours to understand how they had configured their system (no drawings, naturally). They had an ungrounded 480Y277 system. They had even removed the bonding jumpers inside the transformer housings at every drop on the 480V system, which also blew my mind. So they didn't understand grounding OR bonding.
We did manage to get them to approve bonding the equipment, but they told us we could NOT tie the service to any ground rods. I said we MUST tie the service entrance ground to earth via an electrode system of some sort and they said absolutely not.
At that point, I called the frickin' utility and had them send a couple guys out to explain why ground was needed. The breaker operation argument didn't work, because the customer had been told you don't need ground for a breaker to operate. The lightning protection argument didn't work, but--even though they had aerials on their roof--I did not understand why (they had just one insulated downconductor--"isolated" from building steel--running way out to an electrode at the edge of their property, and it wasn't tied to the service ground). The "we will shut your power off if you donít do it" argument did work--imagine that.
This was originally a thermography job, and it quickly morphed into a battle with a customer--in this case, it was a public safety issue and we couldn't just walk away from it. Half the crew walked off the job when they found out there was NO grounding, further complicating this project. They said they'd come back to fix that if the utility would shut the power off (which they did!). Our guys were afraid of being electrocuted from touching a raceway feeding the 277V loads.
That was the most screwed up place I had ever seen. I told my boss they must have a collective IQ of about 40, and he told me to quit flattering them.