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InvalidError

join:2008-02-03
kudos:5
reply to rocca

Re: Fibre Installers

said by rocca:

For others reading/considering this - just FYI, using cat5e between buildings often creates a ground differential during storms which will blow out the ports on the switches attached.

Good NICs and switches have isolation transformers between the cable and electronics which can handle 2-5kV ground potential difference and eliminate the associated common-mode voltage spike so unless there is a lightning discharge through/near the grounding point or building wiring exceeding the transformers' rating, the likelihood of blowing up ports in a storm is low - DSL modems have ~1km of wiring to the DSLAM and millions of them have no trouble surviving thunderstorms.

Cheap equipment on the other hand may use capacitive coupling between chips and wiring, which would send a common-mode voltage spike directly to the chip. Thankfully, equipment cutting such dangerous corners is very uncommon.