Re: why ground an alarm panel.

[robertlbass@xxxxxxxxxxx]

> (the following looks like it may sound like I'm arguing.  I'm not.  I am =
just trying to get to the meaning of 'best'.    )

Questions and answers are what the newsgroup is for.  Well, that plus a
few flames... :^)

> Thank you Robert for your response to this and others that you have
provided in months/years past.  Very appreciated.)   :-)  :-)  :-)

You're most welcome.

> Robert, I had a question.  You mentioned in an earlier post on this threa=
d=2E..

>> that is not the best place to earth your panel.  The best method is to c=
onnect it to the building's common earth ground...

> If someone was putting an alarm in a house from, say, the 1950's that had=
 no ground originally and had various electrical upgrades over the years, I=
 can understand the cause for concern and reasoning for running a copper wi=
re from the alarm panel directly to the common earth ground.

Although there is the possibility that the outlets are not properly
grounded that's not the primary concern.  If you connect the panel's
"earth" terminal to an outlet the lightning will have to pass through
multiple connections before reaching the ground rod.  Each of these
connections adds a little resistance.  Additionally, there are often
numerous bends (some of them tighter than a hard 90=BA) in the
electrical wiring in a home.  LIghtning likes short, straight runs with
the least impedance.  Anything that hinders its course can cause it to
look for another route and that route can easily be through your
electronic gear.

> If someone was putting an alarm in a house that was less than 5 years old=
 that was built to code and properly inspected and they have absolutely no =
reason to believe that anything was done wrong.  Why not just use the groun=
d at the outlet?

See above, please.

> I'm not arguing, I just don't understand why that won't be completely
adequate?

No problem.  The objective is to make things clear.  If you're unsure
of something, ask away.

>  If someone were putting an alarm in a new construction house and the wal=
ls were all still open and the installer could physically see and test that=
 the ground on that piece of Romex is connected to the buss bar in the brea=
ker panel which is connected to the buss bar in the meter which is connecte=
d to the ground rod.  Wouldn't that be more than adequate?

Not really.  Modern alarms have some pretty sensitive circuitry in them
and you really want to have the best possible ground connection.  That
means you need to keep the run short (less than 10 feet if possible).
You want a direct connection from the panel's earth terminal to the
ground rod.  Make gentle, radiused turns in your grounding conductor,
too.  I know that sounds silly but it's true.  You don't want any hard
right angles bends in the ground wire.

> Thanks again for your well thought out responses...

[blush]

> And while I'm at it, (hypothetical situation.  This is probably more a co=
de question than anything.) if it were an install in a house from the '50's=
 and you run the new dedicated wire from the panel screw to the building's =
common earth ground.   What gauge wire should that be?

I use the largest that will fit under the screw terminal -- usually 12
or 14 gauge.

> The Ademco manual didn't specify as far as I could see.  Would the wire n=
eed it's own new ground rod, bonded to the other(s)?

No.  Just connect it to the main rod, using a strong ground clamp.
Home Depot has them in their electrical department as does every
electrical supply house.  The most common are a rigid brass clamp or a
flexible copper strap.  I like the brass ones but either type will do
the job.

Caution!  DO NOT slip your ground lead into the ground clamp of another
service provider (such as the telco, CATV or electrica service.  If you
do a service tech may cut your ground off and never tell you about it.

> If there is only one ground rod can I clamp my wire on using a new clamp?

Yes, that is the proper method.

> Or can I just loosen the existing clamp and stick my wire in it?

No.  See above, please.

> If there are multiple rods (a big one for power, a small one for phone, a=
 small one for CATV) all bonded together does it matter which one I clamp t=
o?

If they're properly bonded together you can connect to whichever rod is
closest to your panel.

Regards,
Robert L Bass
www.BassBurglarAlarms.com