The answer to this question appears at the end of this newsletter.


Repair Your Procedures, Too
Over the past couple of decades, various initiatives, such as ISO9000 and TQM, have influenced maintenance practices. One of the positive developments was the documentation of repair processes. People performing repairs without written procedures were said to be “repairing per trade craft.” That’s another way of referring to the “wing-it” method.

Documentation allows you to standardize each repair process to what is presumably the best procedure. But in many facilities, the documentation has become so unwieldy over time that people ignore it and revert back to the wing-it method.

Review your documentation for bloat, and ruthlessly cut it. Otherwise, its existence is pointless.


Fuses and Motors
If you use fuses for motor overload protection in a 3-wire grounded system, you must insert a fuse in each ungrounded conductor and also in the grounded conductor [430.36].


Operation
NEC in the Facility
You’re supposed to make appropriate provisions to minimize the possibility of damage to transformers from external causes where the transformers are exposed to physical damage [450.8(A)].

Noticing that the only protection for a 75kVA transformer was a caution sign, a facility manager had a bollard installed in front of it. Later that same week, a lift truck driver drove around the bollard and hit the transformer. Lesson: Sometimes, an obvious improvement may not be enough.

You’re not required to prevent mechanical damage, but failing to minimize the likelihood can leave you open to personal liability for damages. You don’t want to be the person blamed when a lift truck driver takes out a critical transformer, and you certainly don’t want people injured or killed in your facility.

To comply with 450.8(A):

• Examine the transformer environment for potential sources of physical damage.
• Analyze mitigation steps, such as relocating the transformer or reconfiguring specific aisle ways.
• Evaluate physical barriers for adequacy. For example, two bollards spaced at less than the width of a lift truck will prevent lift truck entry.
• Erect physical barriers per standard practices. For example, anchor bollards at sufficient depth.
• Add barrier inspection to your PM schedule. Where there is evidence of repeated strikes on a barrier, something is wrong, and it’s only a matter of time before that barrier is breached or somebody is injured. Fix the underlying problem.

Usually, the easiest way to fix this problem is to bond from that driven rod of the network to the grounding point of the power system. If the location of the driven rod makes this impractical, you will probably need to remove the rod and run a bonding jumper “farther upstream.”