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A mouse took down my factory!

Can you believe it?  Preventative maintenance increases safety and understanding your equipment can help keep you safe.

Preventative maintenance can help ensure your equipment is not damaged, as a result it keeps employees safe and it can also help to eliminate unplanned downtime.  Visual inspection of the exterior can also go a long way.  How often should you open your panels and look on the inside though?  You can't see on the outside where something like a mouse can enter.

NFPA 70B 2016 outlines the Recommended Practice for Electrical Equipment Maintenance.  Section 11.17.5 covers Inspection Frequency and Procedures.  This section states that
"Routine infrared inspections of energized electrical systems should be performed annually."

NFPA 70B recommends you open your panels annually this is also a great time to do other preventative maintenance.  Visual inspection is a great example and easy.

What should you be looking for?

  • Holes from the outside world
  • Evidence of water and or rust
  • Missing guards, covers or fasteners
  • Brittle or melted insulation
  • Evidence of excessive heat that the infrared camera might not see.  If the equipment is not under load at the time of scanning then no heat will show up
  • Loose connections
  • Smashed / bent / crushed conduit

Rozel had a customer mention a "nuisance trip" and the maintenance person had already tested the equipment and they verified the equipment was not at fault.  Proper device coordination was already established.  A ground fault was most likely the cause of the fault.  No obvious event caused the ground fault (i.e. fork lift running into conduit) however, there was obviously a cause to this issue.

Preventative Maintenance

From the outside this panel looks perfectly sealed:

hole in panel Preventative Maintenance

Upon further inspection it was discovered that the inside was not sealed:

breaker Preventative Maintenance

This might not seem like a big deal.  Look closer:

note the conductive path Preventative Maintenance

You'll see the culprit:

We've also encountered many live mice in large outside padmount transformers.  Luckily no one was hurt as they jumped and ran from phase to phase.  Here are two videos of surprise "residents" in electrical equipment:  https://www.youtube.com/watch?v=fEQSvd5hE1M and https://www.youtube.com/watch?v=iAedKPBAXRk 

Here's a picture of mouse beds in MCC buckets, you can imagine the potential risk these little guys cause without anyone realizing it:

mouse bed
mouse bed mouse bed

Many people have never heard of NFPA 70B and they don't realize they're already using it.  This standard generates most of the electrical preventative maintenance tasks that we are already familiar with and practicing.  There are many great items in this book and we recommend all factories have a copy on hand:  http://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=70B