On Jun 16, 2007, at 2:01 PM, graywolf wrote: > Please note that I am living in the mountains and thunderstorms > walk through this valley very frequently. When I lived in the > lowlands I never actually experienced lightning damage to my > equipment. And the recent damage was to network stuff which was not > protected. 3 other of the 5 apartments in the building had more > damage than I did. Luckily no fires.
I used to work for a company that designed power equipment that was often used in cellphone towers. We had to put a lot of thought into surge-protection at the distribution, system and module levels. We had a clever machine in our test lab that could simulate lightning impulses on the power line to the IEC 61000-4-5 standard. That is not a nice test to have to design for, especially if you test to a higher voltage than the minimum that the standard requires, but you do end up with a pretty robust product. The standards also cover things like data inputs. For large amounts of energy it is best to use a spark gap to divert as much energy as possible. MOVs work by absorbing and dissipating the energy but there's only so much they can take before they wear out. A combination of both is often used. It is also important to minimise the resistance and especially the inductance of the ground circuit. However, if you need to go that far in a domestic environment I'd be worried :) For lightning-prone areas I agree with having protection at the switchboard, in addition to good surge protectors on the equipment that you can't unplug, and don't forget the phone/cable lines as well. We don't often get thunderstorms in this area, and when we do I can watch the connection light on my DSL modem blink off for a few moments every time there's a flash of lightning. I tend to unplug it in that situation... - Dave -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
