Can Magnetic Contact Lose Effectiveness?

[johndoe74]

I have a weird situation here. Last night we had a thunderstorm all night long and late in the night I noticed that one of my zones is now 'opened', even though the magnetic contact is right next to the zone sensor.

I double checked wiring on the panel and at the window, and they're OK. So there are two possibilities here: 1) Somewhere inside the drywall, the wiring became loose, 2) Magnetic contact loses its magnetism due to the storm?

I don't even know if it is possible for a magnetic contact to lose its magnetism, but it seems more plausible because nobody has come anywhere near the zone, so a loose wire is unlikely.

Has anyone encountered this before?

 

[PaulH]

A lighting strike nearby could produce a large EM pluse that could magnetize the 'leaves' in the switch causing them not attract. I don't know how close a strike would need to be to neutralize a magnet.

JMTCW

 

[Digger]

I doubt its the magnet. Try putting an EOL Resistor on the zone at the panel to make sure the panel was not damaged by the storm. If that is ok try shorting the wiring at the contact.

I would think that the wiring or the switch is the problem with a slight chance of it being the panel (transient from the storm might have blown the zone)

When I was on vacation we had a bunch of storms and I came home to a locked up keypad that has lost communication with the panel. The wiring is ok but the keypad is frozen in armed state with an alarm condition. Strange but it happens. Lightning can do lots of damage (I am only assuming it was the lightning in my case)

 

[pete]

um . . . you can test the magnet with a peice of metal
Pete C

 

[Steve]

I have seen that sometimes the reed switch just gets 'sticky' and can stick open or closed. You may want to just tap the sensor to see if it changes.

 

[elcano]

Is it possible for the reed to get burned because of a high induced current EMF?

 

[johndoe74]

Well, I tested the zone with EOL and it works. Also made sure that the magnetic contact is working. So now it's down to wiring or the reed switch.

Where can I buy a reed sensor and how easy is it to change the reed switch? Mine came prewire so I have never done this before. Thanks.

 

[Digger]

Radio shack has a VERY limited selection of reed switches if you want to buy local. Most alarm equipment distributors dont sell over the counter to the general public.

If you are willing to buy over the net there are tons of places. Auotmated Outlet (Martin) and a few others on here sell to the DIY market.

Heck I bought some great tiny ones on eBay last year.

TANE makes a decent switch as do many others.