Lightning surge protection on underground network cable 1

[nicole10g]

My company have an automatic outdoor carpark barrier system installed on three exit points. This carpark barrier system are interconnected to a master network system which include booth payment counter, autopay console and proximity card access system. Since the carpark barriers are installed outdoor, the comm cable are buried underground. Sometimes during a thunderstorm, the NIC card of various system were damaged which we think is the surge from the lightning to the underground network cable. we have installed a Furse ESP 06D on all the NIC however the recent thunderstorm kill 3 of the NIC card. Any suggestion to help to improve the situation is highly appreciated.

 

[VEBill]

So to confirm, all lightning damaged items were associated with the Ethernet cabling, and nothing else in the system was damaged? If true, then that's clear cut evidence where the surge originated.

Good luck with the fibre optic conversion. It should eliminate at least that particular damage mechanism. Hopefully it doesn't introduce any other weak spots.

 

[nicole10g]

Yes, it is confirmed that the damages all related to the network components. Now the carparking system is up and running again.

 

[djs]

I typical lighting strike is not 20kA. It is more in the order of 200kA. All surge suppression devices are rated in maxium surge capacity. Typically signal (non-power) surge devices are rated to 10 to 20kA. Power surge devices can are are rated much higher. Apply a 200kA surge to a device rated 10kA and it explodes. I have photos to prove it. Even is cases of large scale, large size power surge devices, in the event of a direct strike, it will conduct the surge to ground, but destry itself in the process. Fortunately direct strikes are very-very rare. By direct strike I mean that the lighting stroke actuals hits a conductor.