Re: Causes of Ground Faults

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 ??

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all of the above caused by DIY'er taught over the phone in 30 minutes by unscrupulous retailers.

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This is one of my all time favorites, especially when it fills the pipe up behind the device. Then the customer says that YOUR installation is junk (because they can't pressure wash an electrical device)! After that it is always nice to have them stand right there when you remove the device and hear the water making a good glug-glug-glug sound as it pours onto the floor. Please sign the service ticket, thanks and see ya next time! I have had customers in auto garage shops pressure wash keypads, but it's just not the same type of fun for some reason. Mostly because the system goes nuts and it looks like the keystone cops as they try to turn the system off without a working keypad.

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What about the CAT HAIR!!

Does everyone know what I mean by cat hair? It's the fiber that comes in the jacket... No, Jack.. It ain't complimentary floss!

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G. Morgan

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".

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