Re: why ground an alarm panel.

[w_tom <w_tom1@xxxxxxxxxxx>]

  As Mike has correctly noted, the term "safety ground" does
not exist in the code.  Other expressions such as bonding and
ground are used.  Well, which grounding?  Grounding for
earthing or grounding to breaker box neutral bar?  You are
expected to know which ground is discussed. IOW I have made is
simpler for the layman.  I have renamed what the various codes
call for by using more easily understood terms such as "safety
ground".  I have referenced overall concepts in various codes
into 'easier to grasp' terms - "human safety" and "transistor
safety".

  Numerous codes apply including UL, NEC, and maybe some from
your utility.  However all those codes come down to one
fundamental point - a point more important than codes - a
point based upon the purpose of all those codes:
>> If it has conductive parts that a human can touch, then
>> somehow those parts must connect to building's safety
>> ground system.

  Furthermore, that concept should be intuitively obvious.  If
enclosure is sheet metal, then it must have a safety ground to
meet UL requirements.  No way around that fact.  Safety ground
would be a third prong on AC electric plug.

Nomen Nescio wrote:
> Would you please cite a code reference for this?  Please keep in
> mind that the typical alarm control panel enclosure is 18 to 20
> gauge sheet metal, and is not equipped with a grounding terminal.
> As you know, a sheet metal screw is not an acceptable method of
> attaching a grounding conductor to an enclosure, therefore a
> sheet metal circuit board mounting screw would not be an
> acceptable method of grounding the enclosure.