On Fri, 20 May 2016 11:45:39 -0700 (PDT), westom
wrote:

On Friday, May 20, 2016 at 4:08:59 AM UTC-4, Gz wrote:
Came in on phone line. Phone line also needs protection.

Phone line must already have been protection installed for free. Unfortunately that protector is only as effective as an earth ground that you provide and are responsible for maintaining.

Most common incoming surge path is AC electric. Once inside, it hunts for earth destructively via household appliances. Damage means both an incoming and an outgoing path must exist. Damaged are appliances that make a best outgoing connection to earth.

Incoming on AC mains into an answering machine. Outgoing to earth via the telco 'installed for free' protector. Damage is often on the outgoing path.

You assumed the outgoing path was an incoming path. Why would a surge enter on a protected wire. And not enter on the most commonly unprotected wire - AC electric. You had damage because a surge was all but invited inside. It more likely found an excellent outgoing path to earth destructively via the answering machine and phone line.

Modems were the first things we determined would benefit from a point
of use protector and with thousands of them installed, we had lots of
chance to test the theory. The telco protection was designed to keep
an old style Western Electric phone from catching on fire, not to
protect CMOS. On a recording volt meter we saw alarming transients
getting past their "gas" protectors. If you still had the carbon rods,
you might as well just tie a knot in the cord.
Certainly you need to be sure the Telco protector is bonded to the GES
on the service but that is not all you need. The longer the phone
wires are on the customer side of the Dmark, the less protection you
have.