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Default Power line follies

On Monday, April 29, 2019 at 1:27:31 AM UTC-4, wrote:
On Sun, 28 Apr 2019 18:19:51 -0700 (PDT), Its Me
wrote:

On Sunday, April 28, 2019 at 8:25:39 PM UTC-4, wrote:

They certainly only looked like a carbon/graphite rod that connected
the signal lines to ground to me. I suppose you could "fire" them up
but they were still just resistors that bled static off the line. I
may still have one here somewhere because that was what UTS was using
here until Sprint gave me a new Dmark. I doubt I threw it away. As
long as I was just using old school phones I didn't care but when I
hooked up a modem I had them change the protection.


They, in their new state, were just high resistance carbon rods. But they didn't bleed off static. They were primary lightning protection that basically shorted when the big lightning spike came in. That's how they bled off the big spike. It certainly wasn't because they were a high resistance resistor. They gave their lives to protect the equipment.

In the old days after a storm, and your phone didn't work or had a big hum on it, that's what the repairman changed out on the box on the outside of your house to fix it. That's what carbon protectors do.


Sounds like a resistor to me and when it gets wet it is a very low
resistance resistor.
There is no "active device" in a stick of carbon and no magic.
There might be an "over heating to ignition" effect and "fire" in that
sense but I have seen half watt carbon resistors give up their life in
the same way. It does get you closer to the bad part tho ;-)


I was curious, and found this:

http://doc.telephonecollectors.info/dm/56Aug_BLR_P298_Telephone_Protectors..pdf

Turns out they are just a carbon block or tube with an air gap to ground. The air gap fires when a lightning surge comes in. Big enough surge permanently bridges the gap and then it has to be replaced. I've always seen the later version of the second design that had hex head rods that screwed in.
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