Comcast Modem Surge Protection

[CRCom]

Never had problems until lately with 2 surge damaged phone systems (Lightning), Both with Comcast dial tone feeding 4 lines.

What do you do to protect the system other than the standard C.O. line protectors? Comcast does not provide any protection on the dial tone. There is a dependable UPS on the power to the system, and secondary protection(sneak fuses) on the C.O. lines from before the Comcast install with no problem. Could a bad or no ground at the Comcast primary connection be the fault? It did not look good when I checked it. Loose and corroded.

Thank You for any help

 

[mforrence]

I would think that lines from a Comcast gateway would be fairly well protected as the lightning would need to traverse the gateway's circuit board. In these cases, did the Comcast gateway suffer any damage? I would make sure that all grounds are properly bonded to ensure that surges aren't finding a better path to ground via your phone system.

 

[CRCom]

Thank you for the reply.
Well, it did fry the Comcast modem the first time. Replaced the system and it happened again after adding a dependable UPS. That's why I'm thinking it's a Comcast surge. I plan on adding more protection on the lines from Comcast. I know I shouldn't get into redoing the way the lines feed the equipment from the modem, (and the bad ground)- but I will, just to get this resolved

I should add that I didn't install this system initially. Lucky Me!

 

[westom]

First understand why damage happens. A destructive current found a path to earth apparently via your phone systems. If properly installed, the Comcast already has the best possible protection. A wire from the cable to single point earth ground. A current that is earthed BEFORE entering the building does not find earth destructively via the phone system or anything else.

However, the system must be implemented on everything. A lightning strike far down the street is a direct strike incoming to everything electrical. Is everything damaged? Of course not. To have damage, both an incoming and an outgoing current path must exist.

Incoming on AC mains. Outgoing to earth via the Comcast (if properly earthed). Because you all but inviting a surge to enter and go hunting destructively via AC electric.

Every incoming wire inside every cable must connect low impedance (ie 'less than 10 feet') to earth BEFORE entering. Otherwise all protection is compromised.

Comcast has the best protection possible - a wire connection. Other wires cannot connect directly (ie AC electric). So we do the next best thing. We make the same connection with a protector.

That is what a protector (or UPS) does. Either make that low impedance (ie 'less than 10 foot', no sharp wire bends, no splices, etc) connection to earth. Or it does virtually nothing but enrich the manufacturer.

A protector is only as effective as its earth ground. Only then do you know where hundreds of thousands of joules harmlessly dissipate.