w_tom wrote:
As others have noted, grey telephone box (NID) contains a surge
protector that is effective if earthing connection exists. Phone will
work with or without earthing wire. But without that wire, then human
and transistors are both at risk and phone installation violates code.
Telephone installations must have that 'whole house' type protector and
earthing. Earthing wire must be continuous, no splices, not bundled
with other wires, short (ie 'less than 10 feet'), and connected to same
earthing electrode used by AC electric and cable company ground wire.
As others noted, you want that earthing wire corrected - and without a
splice.

Hum may be from a partially damaged surge protector inside NID.
Determine whether hum is inside house or in NID box. By doing as Alan
has recommended, open 'Customer access' side where your wire connects
to their box via RJ11 phone plug. Simply disconnect your wire and plug
a telephone directly into that phone jack. If hum is heard, then
problem is on telco and they pay. Otherwise problem is on your wires
and you pay (or fix it yourself).

Thanks to all who replied. I did do as you say, on the first day. The
hum was the same when plugged into the NID. I called the telco while
outside in the drizzle, and still plugged into that NID jack. The
customer rep told me that someone would arrive the next day, and if
they plugged into the outside jack and there was no hum, I'd get
charged $99 for the visit. I said that the problem might be gone the
next day, which was forecasted to be dry and sunny - so I told her not
to send anybody.

That decision saved me the $99. By 11am the next day, the hum was gone.
But the day after that was rainy again, and the hum was back. I
disconnected and reconnected the ground, which had no effect
whatsoever. Next, I fiddled with the wires inside the NID. Then the
phone was clear. A half hour later, the hum was back. I removed the
plug and sprayed electronic cleaner into the jack. (Note that wasps had
made a nest inside, since abandoned - but there could be some fine
organic material all over.) The noise came and went with no rhyme or
reason on that day, but was gone the following day.

There have been some slight rains since, with no hum. I guess I have to
wait for bad rains, and try to schedule a visit while it is still in
the rain period. It's a crap shoot.

In the meantime, where could I get the exact same grey wire that the
telco uses for ground?
I don't want to one day have them show up and charge me a small fortune
to redo it. Thanks.



That 10 AWG earthing wire (they are responsible for it) must be
fixed. But first determine where problem exists - on your side or
theirs.

wrote:
There is a heavy wire running from the outside phone box (company side)
to a big spike in the ground. I clipped that with hedge clippers some
years ago, then I repaired the break merely by twisting the ends back
together and that worked okay for many years..

Today there is a bad, constant hum on all phones. When I plugged a
phone into the outside box jack, the hum was the same. It has also been
raining for several days.

Can a bad ground cause a hum? Vigorously shaking the ground wire caused
no static. What should I expect if I disconnected the ground entirely?
(As I write this, I'm thinking maybe with corrosion the path to ground
is now non-existent.)
...