Suitable Class of Surge Protective Device

GA! Teach him(her) how to fish, instead of giving him(her) a fish.

I was about to say the same thing!

Thank you very much for your valuable references. For overhead line, it is clear that it will be subjected to direct lightning strike. But for underground cable, it is not clear very much. At the transformer (because it is on the ground and if there is no any lightning protection), it can be subjected to direct strike and surge can be propagated to the load through underground cable. Except this, I think that surge can be created in underground cable only by induction due to indirect strike.

So, what are you going to do?

I think it is better to use class 1 surge protective device because of possibility to subject direct lightning strike at the Transformer or load (because cable is on the ground and there is no any lightning protection at transformer or load end).

All that is needed, then, is a second person check on the proposed design:

• Bounce the idea off a mentor at the facility before invoking it.

Lyn: Thanks for those links. I'm assembling an article on surge protectors for my local computer support group. I printed these for later reading, but the third one didn't work for me.

https://blog.schneider-electric.com/power-management-metering-monitoring-power-quality/2013/03/19/how-to-choose-the-right-surge-protector/