Powering up puzzle
#14
(2017-06-15, 12:05)BobW Wrote: Not going to have a big discussion here about this.

Wise, lightning protection is up with politics and religion.

(2017-06-15, 12:05)BobW Wrote: what I suggested doing is covered by article 810 of the NEC.

An American thing, this side of the pond finds it all a bit weird.  The UK and probably Europe as whole don't "ground" feeders, phone lines(*), etc where they enter the property. Exposed conductive parts (pipework, equipment chassis (unless double insulated, fittings etc) within a building are bonded to the "Main Earth Terminal" (MET) and that is connected to any conductive service pipes at the point of entry as well as the supply earth. But this is to ensure a low earth loop impedance for fault protection and to ensure that all exposed conductive parts are at the same potential.

Lightning "protection" in the UK is done with lightning rods connected to low impedance earth spikes via 1 x 3/16" ish copper strip. These leak the charge building up between cloud and ground, hopefully keeping the potentail below that required for a strike to occur. But you'll only find lightning rods on large commercial type buildings not on peoples homes.

(2017-06-15, 12:05)BobW Wrote: It's tough to survive a nearby flash, but pretty much anything that picks of current at point of entry helps.

A nearby strike is going zap stuff or not. A few pence device (MOV, gas discharge tube, WHY) isn't going to make much difference, the energy levels are just too high. I'm with Cutty, if you have some "protection" device how do you know if that device is still functional after a nearby strikes or is that strike?

I don't know the details of that American electrical code but I doubt it is written with much attention paid to keeping noise out of sensitive RF receivers. With the E-field screen grounded when there is a storm in the vicinity it'll start to act like a lightning rod. There will be current flows and thus voltages in the screen. The E-field is an unbalanced input it'll "see" the screen potential moving around as a signal.

Found the spec of that inline coax supressor, triggers @ 65 V, 500 A, 2 x 10 us. If I've got the maths right [ (65 * 500) * 20^-6 ] = 6.5 joules, a tiny amount of energy. I like the claim "Does not degrade with repetitive strikes" decent strike and it'll be degraded all over you back yard! To be fair it doesn't make any claims about lightning.

Sorry BobW, as you can tell I'm of the view there is not a lot you can do about lightning, at least not without spending a small fortune on protection. Switching transients on your incoming electrical power is another matter but they don't have anything like the energy of a lightning strike.

(*) Just remembered phone lines have a gas discharge tube across the pair. No ground connection though.
Cheers
Dave.

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Messages In This Thread
Powering up puzzle - by MonkeeRench - 2017-06-12, 21:15
RE: Powering up puzzle - by kevinmcc - 2017-06-12, 23:03
RE: Powering up puzzle - by MonkeeRench - 2017-06-13, 15:51
RE: Powering up puzzle - by kevinmcc - 2017-06-14, 00:13
RE: Powering up puzzle - by MonkeeRench - 2017-06-14, 02:15
RE: Powering up puzzle - by kevinmcc - 2017-06-14, 05:03
RE: Powering up puzzle - by DelandeC - 2017-06-14, 08:42
RE: Powering up puzzle - by allsorts - 2017-06-14, 10:03
RE: Powering up puzzle - by kevinmcc - 2017-06-14, 23:12
RE: Powering up puzzle - by BobW - 2017-06-15, 04:11
RE: Powering up puzzle - by cutty - 2017-06-15, 05:38
RE: Powering up puzzle - by allsorts - 2017-06-15, 16:20
RE: Powering up puzzle - by kevinmcc - 2017-06-16, 22:57
RE: Powering up puzzle - by BobW - 2017-06-15, 12:05
RE: Powering up puzzle - by allsorts - 2017-06-15, 18:18
RE: Powering up puzzle - by Jon Point - 2017-06-16, 01:11
RE: Powering up puzzle - by allsorts - 2017-06-17, 22:39

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