Re: why ground an alarm panel.

[Mike Sokoly <secure15@xxxxxxxxxxxxx>]

w_tom wrote:
>   A rule for someone who intends to meet the purpose of the
> National Electrical Code and UL is simple.  If it has
> conductive parts that a human can touch, then somehow those
> parts must connect to building's safety ground system.
>
> mikey wrote:
>
>>"Bill" <bill190nospam@xxxxxxxxx> wrote in message
>>news:3vmfvmF16g7jeU1@xxxxxxxxxxxxxxxxx
>>
>>>...
>>>And an air conditioning system can malfunction sending house
>>>current through all the metal vents and an alarm wire might
>>>be shorting to same.
>>>
>>>All rare, but possible...
>>
>>I'm sure it happens, I'm re-considering my stance.
Let's Talk amongts ourselves.

Article 100
  Bonding
Permanent joining of metallic parts to form an electrically conductive
path that ensures electrical continuity and the capacity to conduct
sfaely a fault current that is likely to be imposed. It is to creat a
low-impedence path for the removal of dangerous touch voltage from metal
parts

Grounded
The connection of metal parts TO EARTH for the purpose of directing
lightening AND OTHER high-voltage surges to ground.

Ground- The earth

Grounding of Electrical Equipment
Metal parts of electrical equipment in a building are GROUNDED to earth
by means of the grounding electrode conductor to an appropriate
grounding electrode (EARTH)
Grounding equipment also helps prevent the buildup of hi-voltage static
discharges on metal parts. Grounding metal parts to earth does not
protect equipment from lightening voltage TRANSIENTS.

Bonding of electrical equipment
To remove dangerous votage the metal parts of raceways, cables,
enclosures, and equipment SHALL be bonded together. In addition the
metal parts SHALL be bonded to the grounded (neutral) terminal of the
supply source.

The NEC does not permit a ground rod  to be used as a sole
EQUIPMENT(bonding )conductor. A supplementary electrode IS permittted
but not alone, there must be equipment bonding conductors to the
disconnect equipment.

Supplementary Electrodes
Are NOT required by the NEC. Are NOT required to be directly connected
to the grounding electrode system nor is the conductor required to be
sized by NEC 70 Article 250.66. If it is aground rod it is NOT required
to comply with the 25 Ohm resisitance requirement. In addition EARTH
cannot by used as the equipment grounding conductor!

Termination
No more than one conductor SHALL terminate to the grounding electrode
and only by a listed fitting.

Communication Systems
An accessible and external means SHALL be provided at the service
entrance for grounding communication equipment.

Bonding of separate electrodes
a 6AWG bonding jumper is required for bonding COMMUNICATON SYSTEMS
to the Power grounding electrode SYSTEM if a supplementary electrode is
used away from the service entrance location.

Note bold print.
Above from the NEC Code 2002 and Understanding the NEC 2002 by Mike Holt.
Mike has suggested to me that if we want we can take up the topic at his
Code Forum on his Website ;
www.NECcode.com