Re: Causes of Ground Faults

["FIRETEK" <firetech(change-the-ch-to-k)@telus.net>]

Add to all of the ones mentioned:

The cover plate screws on full JB's.  As you're turning them in, they're
"rubbing" against the wire and "Voila"- ground fault.

How about this rather strange one?

Large Notifier AFP 400 with two 5000 satellite panels.  The "installer"
(probably closer to Bass' definition of one) "T" tapped one of three of the
400's remote annunciators (data loop only - the annunciators are powered by
the respective 5000's power supply which are incidentally NOT commoned to
the AFP-400's power supply).  As soon as you hook the sucker up, you get a
GF.  The "installer" solved this problem by snipping a resistor on the power
supply board that turns out to be part of the ground fault detection
circuit.  Neither of the 5000 panels detected a ground fault after this
operation.

I use "installer" singularly but there were too many "hands" in this one to
pin the blame on one particular individual.  The original verification
(performed by none other than Grinnell - who was at the time the authorized
Notifier Rep) was subsequently rejected by the AHJ because the Notifier
equipment wasn't installed in the proper backboxes.  The contractor had to
make good and re-verify the system.  The second verification was also
rejected because it was performed while the system was registering a "ground
fault".  The second VI only made it into the hands of the AHJ four years
after the system was installed.  The contractor (either deliberately or by
accident - take your pick) failed to transmit a copy of it or call for a
"final".  Needless to say, "heads will eventually roll" and I will be only
too happy to help hold the "axe".


"Michael" <sirflannelS@xxxxxxxxxxxx> wrote in message
news:j5geo2535pd69ppr41o5sliiccahf8cp3q@xxxxxxxxxx
> On 18 Dec 2006 12:12:04 -0800, jonlevis@xxxxxxxxx wrote:
>
> >I have been asked to present a training seminar regarding fire alarm
> >systems, in particular addressable systems. I am looking for common
> >causes of Ground Fault Troubles that people have come across. Any one?
>
>
> Let's see....
>
> Wires stripped back too far behind devices touching back box
>
> wires stripped back too far in the control panel
>
> wires pulled tight and tye wrapped or secured around sharp metal
> corners
>
> wires pulled roughly during wiring, causing nicks in the wire
>
> heat detector and pull station  in resturaunt kitchens getting sprayed
> down during nightly cleanup
>
> leaky roof above smoke detector
>
> non-weather resistant horn strobe placed outside, moisture getting
> inside box, corroding wire and damaging horn strobe
>
> 50 feet of slack crammed into a 4-O box behind a horn strobe getting
> nicked and crushed inside the box
>
> Anyone think of anything I missed ?? <g>