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Tracing Ground Fault on Conventional Vs. Addressable

PostPosted: Sun May 21, 2017 8:40
by Zeus
Hello,

I would like to ask you all a question about ground faults. How would you go about trying to trace a ground fault for a conventional panel compared to an addressable? I know that there may be a few different procedures for each and I would love to hear your opinions. I have started to deal with more addressable and have been having some trouble with them.
:?

Thanks,

Zeus

Re: Tracing Ground Fault on Conventional Vs. Addressable

PostPosted: Sun May 21, 2017 11:25
by FIRETEK
Ground faults are typically a pain in the butt, but addressable systems are usually pretty easy to troubleshoot *IF* certain documentation and types of devices are present. Isolators make tracking a ground fault a pretty easy exercise, but intelligent isolators can home in on an area without having to wander through the building. This is where "documentation" comes in. If you're in Canada, the Fire Code states that the Verification Appendix "C" has to be retained on site for the life of the system. On programmable systems, the individual doing the Verification may not be the individual that's doing the programming, so, in order to perform the Verification, some other key documentation has to be gathered, reviewed, and hopefully included in the final report. This includes the device descriptions and addresses. Device descriptions will also include their locations, so if the ground fault you're investigating happens to include "dumb" isolators (they don't have an address), then finding them and disconnecting the loop serving each floor area will very quickly identify the area of the ground fault. If they're "smart" devices (have an actual assigned address from the panel), you can turn them "on" and "off" at will (as long as you have their addresses). If there are NO ISOLATORS installed, then you have a problem much bigger than a simple ground fault. Keep in mind that the requirement to LIMIT a fault on the Data Communication Link to a single floor area has been part of the Canadian Installation Standard (CAN/ULC-S524) since the 1991 version was published. If you're in the unfortunate situation of working with a system with NO ISOLATORS, you're going to have to try and find your ground fault the old fashioned way. Disconnect the DCL Loop at the common control. If the ground fault doesn't disappear, then it may be in another circuit. Isolate the common control by disconnecting your signalling outputs, the connection to your remote annunciator. Check to see how the annuncators are wired. I've seen them "T" tapped in one installation that was the subject of an upgrade. If you've identified the DCL loop as the culprit, then you're going to have to employ the time-honoured method of splitting the circuit. If it's a Class "A" loop, disconnect either the return or the supply side of the Circuit first at the FAS. If the ground fault disappears, it's somewhere in the field between where you are and the control panel. Reconnect the loop and move "closer" to the panel.

This would be a good subject for a Tech-inar session... http://www.traininginstitute.firetechs. ... cation.asp . :-)

Re: Tracing Ground Fault on Conventional Vs. Addressable

PostPosted: Mon May 22, 2017 2:41
by Centurion
Hi Zeus,

In my experience most ground fault are caused by:

1) Installation; wires pinched in a back box or a back box connector screwed in too tightly. :roll:

2) A supervision switch on a sprinkler system that has gotten filled with water after a defective seal.

3) Quite often I get the call after a painter had removed a piezo in a dwelling unit and pinched the wires upon reinstalling it. :roll:
Also water infiltration in heat or smoke detector is a common thing as well

To trace your ground fault, the methods described by Frank in the above post are your best way to go, but I also found a way of doing it sometimes faster if I'm lucky.

I use a meter called SureShot made by Platinum Tools which enables me to trace the distance of an open or a short on a cable.
The meter's price is hefty ( In the $300 and above range ) but it is well worth it.
On a class A circuit you would put your meter on both sides and the difference between the two would give you a pretty good appreciation of the location of your ground fault.

My 2 cents

Re: Tracing Ground Fault on Conventional Vs. Addressable

PostPosted: Tue May 23, 2017 1:34
by FIRETEK
And a much appreciated "two cents" worth, too! Thank you, GaƩtan!

Re: Tracing Ground Fault on Conventional Vs. Addressable

PostPosted: Mon Jun 05, 2017 1:35
by Zeus
Hello guys,

Thank you so much for your replies. Centurion, I will definitely look into buying that device because it seems like it may save a lot of headaches.
And FIRETEK, do you mind explaining in simpler terms? I am still fairly new to the fire alarm industry.

Thanks,

Zeus

Re: Tracing Ground Fault on Conventional Vs. Addressable

PostPosted: Thu Jun 08, 2017 4:46
by FIRETEK
Finding a ground fault can be a challenging process, unless it's something obvious (like water dripping from a heat or smoke detector, or an obvious damp spot on the ceiling around the detector. That's where you would normally start looking. To find a ground fault is the subject of one of our online techinars. http://www.traininginstitute.firetechs. ... cation.asp