Digital signals - lightning protection

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Thread Starter

Daniel Uhrin

Hi,

is it necessary to shield digital signal cables routed outside in buried conduits (dunno whether these are SS or concrete yet) to fulfill lightning protection needs?
 
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curt wuollet

Probably no simple answer. And lightning has a way of doing as it pleases. In plastic conduit, I would shield for sure. Metal conduit may actually render shielding ineffective due to transmission line effects. But you have to be more specific about "digital signals", a line from a microswitch is much, much, different from a RS485 cable. And distance plays a role as does spanning two power systems. And "lightning protection" is a pretty broad term. I worked on a compound in Florida that got hit a couple times nearly every day. It took a while and considerable work before equipment would survive a week. And some of the solutions defied conventional wisdom. In general, I consider overt protection whenever a line leaves a building. But the protection is different depending upon the signal and cable type. And there is much judgement and some magic involved after the engineering. In the end, we don't know much more about it than Ben Franklin did.

Regards
cww
 
Daniel Uhrin... lightning problems can be exacerbated by something as simple as the connections used to ground or earth electrical equipment.

For example, if the groundING or earthING conductor is routed through a piece of magnetic conduit, the conductor MUST be bonded at both the entrance and exit of the conduit.

Regards, Phil Corso
 
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