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Ross Herbert

On 14 Nov 2006 21:23:55 -0800, 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.)

Also, there was a wasp nest in the customer side of the outside box
(but not in the company side). The nest didn't seem to create any
obvious destruction, though. If I connect a phone to the jack on the
customer side, then the nest seems to have no involvement anyway since
the terminals on that side become irrelevant - but you never know.

The 'ground' connection is most likely associated with a lightning
surge protection device if you are in an area prone to lightning. In
normal circumstances a phone line which isn't prone to lightning will
not have a lightning protector and therefore no 'ground' connection.
It is simply a 'protective ground' for this purpose.

Having said that, if there is a protector and it has received a
'splat', it may have broken down and caused one or both legs of the
telephone line to become low insulation to earth, which will cause hum
on your line.

If there is a protector I would try disconnecting it (temporarily) so
that the incoming line pair is connected straight through to the
phone. If hum is still present then you need to do some further
analysis since the fault could be internal to your house telephone
wiring or external to the house in the incoming telco cable. If you
can disconnect your internal cabling from the external cabling jury
rig your phone instrument to the incoming telco pair and then see if
the hum is still present. If it is then the fault is either in your
instrument or in the telco line. Only a known good instrument (or
buttinski) will determine which of the latter two cases it is.

Of course, you may not be allowed to play with your telephone cabling
depending upon your telco regulations so I leave it up to you to
determine. After testing is completed make sure that you restore
everything to the way it was or you might incur the wrath of the telco
if you weren't supposed to be playing with the line.