Fire alarm goes off whenever there is Electrical Storm - ADT System

Old 07-15-05, 03:55 PM
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Fire alarm goes off whenever there is Electrical Storm - ADT System


I had an ADT system installed in my home when I first moved in. Yeah yeah--I'm generally a DIYer, but my house is 100 years old and I was too busy to do all that fishing when I first moved in. Once I looked at the price of buying equipment myself, their deal was a steal for the amount of labor involved in fishing lines in my old house. It's an Ademco system.

Well, I'm past my "90 day warranty" (it was installed during the winter), and now I have problems. We've been getting thunderstorms, and they ALWAYS set off the fire alarm. We even had the fire department come once when they couldn't reach us in time on the phone. The idiots at ADT told me that this is "normal" and "all alarms go off during electrical storms". But, since it's past my 90 days, they'll look at it for a minimum $120 service call!

After this last storm when it went off 3 times, I looked at the panel to just fix the thing myself. The panel is powered by 2 power wires going to a non-ground wall transformer (2 plug). I looked at the screws on the board. One was labeled, "Earth Ground". For some odd reason, there was NO WIRE GOING TO IT! Just a resistor hanging off it (why, I don't know). I'm an electrical engineer, so this makes sense as a cause of my problems. If there's a surge, there's nowhere for the current to bleed off.

So I hooked some heavy gauge wire to the Earth Ground and to my house ground. But I have to wait for the next storm to see if it works. Any other advice on protecting my system from having the fire alarm go off during storms? I also put a surge protector on it, but I doubt that will do much. I'd hate to have to buy a $1000 active UPS or SOLA CVS.
Old 07-16-05, 07:45 AM
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Assuming that the smoke detectors in your system are hardwired, the thing to do is make sure that the wires at the terminals at the smokes are tight. If they are wireless, then the lightning strikes can create a false signal.

It's unusual for an major brand alarm to so consistantly false for storms.

The surge supressors are actually a good idea, especially in a storm prone area. Normally the ground isn't an absolute requirement due to the way ground and neutral in modern residential electrical systems is wired, but in your case, it's worth a shot.

When you get these incidents, have you checked to see if any of your smoke detectors are showing an alarm (steady led)? It's possible that a close strike has damaged one of them, or even something as simple as an insect inside the sensing chamber, and the storm activity tips it past the active point.

Don't get focused on the control unit, often, it's the devices at the other end of the wire that are the culprit.
Old 08-03-05, 10:59 AM
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Thumbs up Fire Alarm Lightning solution

I have researched in this area for 15 years and I have come up with a way to stop this problem. I will need your assistance. You are an Engineer, and you would agree, that if I could create an alternative path way for lightning to go around your system/by-pass your system and at the same time prevent a feed back loop up the case ground. You have to agree, that the tap transformer used on your system is not a ground isolation transformer with a static shield, much less a spark gab between the windings. Normally the problems come in the RJ31X, and also other zones that are attached to HVAC, and metal frames on the window, have a ground loop/difference of potential. You would have to agree that in-line series surge suppression with inductive coils also will play a significate roll.
If you would like to study my approach, you can e-mail me and I will send you pdf files. These files will allow even novice or none technical individuals to agree that I might have the answer they are looking for.

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