Re: why ground an alarm panel.

["Robertm" <Respond@xxxxxxxxxxxxx>]

"w_tom" <w_tom1@xxxxxxxxxxx> wrote in message
news:4395F11C.9569D928@xxxxxxxxxxxxxx
>  To make a decision based only upon number of votes is a
> fool's errand.  First question to ask was, "Were underlying
> reasons for that vote also provided."  It is called  "the
> devil is in the details".  Too many just know without ever
> learning the reasons why.  That is how junk science is
> created.
>
>  Should you only take what I have posted as one vote, then
> reverse my vote.  I now vote for the most destructive
> alternative because you did not first do as even George Patten
> demanded: the good general knows what is happening three
> levels down.  My post provided some underlying details - and
> more than others had provided to justify their 'votes'.
> Knowledge of underlying technical details always trumps a
> thousand votes to the contrary.  Science types always demand
> 'why'.  'Yes or no' is not sufficient.
>
>  If you don't learn and appreciate the functions of grounding
> - why the same wire can serve multiple functions - then you
> have no answer. IOW without the why's, then the real answer
> provided was "I don't know".
>
>  Basic electrical knowledge says everything in the building
> must connect to the common single point ground.  This ground
> defined and essential for human safety.  Which is completely
> different from another single point ground for transistor
> safety.  Yes, both share common wires.  But, for example, the
> AC receptacle ground is not an earth ground for very good
> reasons electrical.  Yes, the AC receptacle ground is
> eventually connected to earth ground through a chain of
> wires.  But it is not earth ground.
>
>  If AC receptacle ground is earth ground, then printed
> circuit motherboard ground is also a good place to earth a
> lightning rod.  But since two ends of every wire is
> electrically different, then each ground is different.
>
>  The answer is not found in votes.  Answer is found in
> science.  The difference between resistance and impedance. The
> underlying reasons why.  How many of those voters even know
> the difference between resistance and impedance?  And how many
> can apply numbers to same?  Therein lies a criteria to count
> only votes based in science - not speculation.
>
>  Immediately, you know this if only for human safety.
> Everything must have a sufficiently grounded (low resistance)
> connection to the building's single point safety ground.  That
> unique safety ground is located inside main breaker box.  That
> safety ground is different from the earth ground.  Just
> another fact that responders must understand before your
> question could be properly answered.  Just another benchmark
> to weed out votes from the technically naive.
>
>  The alarm panel is typically the single point safety ground
> connection from alarm system to the building's single point
> safety ground.  That ground connection essential and required
> for human safety - either via AC power cord safety ground OR
> via dedicated grounding wire.
>
> autonut843 wrote:
>> Thanks for the responses.  I hope it doesn't sound like I'm beating a
>> dead horse, I'm just curious.
>> So it looks like we have two NO, two YES, and one YES/NO.
>> So, if you are a YES and you come upon a panel that is not grounded, do
>> you add it?
>> If you are a NO and you come upon a panel that IS grounded, do you
>> disconnect it?
>> If so, why and if not, why not?
>>
>> Regarding human safety and grounding the cans.
>> The Ademco and Moose cans I am familiar with do not seem to have a good
>> grounding location.  Sure, I could tap in a sheet metal screw and that
>> would cover it but it seems like if they didn't put it there in the
>> first place and they don't mention it in the instructions, then it
>> wasn't intended.  The screw on the board, however, they do mention.
>> You mention that DSC panels do provide hardware to ground the panel.
>> I'm curious, do they have a good connection between the can and lid as
>> well?  If it's a human safety issue I would assume that they have a
>> good non-painted contact between the two.
>>
>> Thanks all, have a great day!

An interesting observation was made that the Ademco screw on the terminal
board is mentioned, not the can. The circuit board attaching screw grounds
it to the can approx 3/8 inch from the terminal. Ground the screw on the
board and you ground the can.

Bob