What is a Friday Afternoon Repair?
A Friday-Afternoon-Repair isn't a repair. It's a way of hiding troubles on a fire alarm control panel so the owner doesn't have to listen to the trouble sounder all weekend. Presumably this is done so the fire alarm service company can return the following week to fix the troubles.
By Douglas Krantz
If the fire panel shows normal, you may never get back to fix a trouble; if the fire panel shows trouble, you'll always come back to fix it.
Sometimes, when replacing a fire alarm control panel, ground faults suddenly show up on the building wiring. The ground faults
actually had been there all along, but were hidden.
The previous fire alarm company had performed a "Friday-afternoon-repair" by disconnecting the ground fault circuitry - - and had the intention of finding the ground fault
the following week. They never got back to fixing the ground fault.
This kind of "fix" is common among some fire alarm service companies, and is a problem.
Whether it's moving the end-of-line resistor
to the beginning of the line, paralleling a single phone line to make the panel think there are two different lines, or disabling the ground fault circuitry, be careful when making the panel normal.
If you don't return the next week, you may never return because, at least from the owner's perspective, there is no reminder on the fire alarm control panel
that the system needs fixing.
The trouble light and sounder on the fire alarm control panel is a reminder that there is a problem. This reminder isn't just for the fire alarm service company; it's also for the owners. If the panel shows its trouble light, and keeps sounding the trouble buzzer, to the owners there's a problem that needs to be fixed
. The owner won't let the alarm company forget the problem, which is actually a good thing.
If you have to leave for some reason, whether it's a broken connection on a class B circuit, bad phone line, or a ground fault on the system, leave the panel in trouble.
Remember, rather than "fixing" the trouble light, you're better off leaving a panel in trouble and explaining the trouble to the owners. They'll be the ones to want you back to fix the trouble.
Having serviced fire alarm systems for nearly 20, Douglas Krantz has compiled his knowledge of the causes of Ground Faults and how to reliably detect them into the book Make It Work - Hunting Ground Faults
. The book shows the three types of ground fault, what equipment should be used with each type of ground fault, and how to locate those hard-to-find ground faults.
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