POE switches and lightning

Mark Mayfield mark.mayfield at metro-inet.us
Thu May 13 18:26:10 UTC 2010

About a month ago, we had a lightning strike near our main campus.  We lost one POE Cisco 3560 completely (apparently blown power supply), and in a separate but nearby building, another 3560 lost the ability to deliver POE, but continued to operate as a switch.  Both had to be replaced. Both were on wiring closet type UPS'es with surge suppression, and those were unaffected.


-----Original Message-----
From: Caleb Tennis [mailto:caleb.tennis at gmail.com]
Sent: Thursday, May 13, 2010 10:37 AM
To: North American Network Operators Group
Subject: POE switches and lightning

We had a lightning strike nearby yesterday that looks to have come inside our facility via a feeder circuit that goes outdoors underground to our facility's gate.

What's interesting is that various POE switches throughout the entire building seemed to be affected in that some of their ports they just shut down/off.  Rebooting these switches brought everything back to life.  It didn't impact anything non-POE, and even then, only impacted some devices.  But it was spread across the whole building, across multiple switches.

I was just curious if anyone had seen anything similar to this before?  Our incoming electrical power has surge suppression, and the power to the switches is all through double conversion UPS, so I'm not quite sure why any of them would have been impacted at all.  I'm guessing that the strike had some impact on the electrical ground, but I don't know what we can do to prevent future strikes from causing the same issues.  Thoughts?

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