Do reed switches go faulty?
Discussion
With the cold weather, the alarm sensor on my back door has been going a bit bonkers, triggering the alarm at silly times of day and night.
Its almost certainly related to the cold temperatures, its a wooden door and not particularly well sealed.
So do magnetic reed switches tend to go faulty in this manner? Its a cheap replacement either way, but I just wondered.
Its almost certainly related to the cold temperatures, its a wooden door and not particularly well sealed.
So do magnetic reed switches tend to go faulty in this manner? Its a cheap replacement either way, but I just wondered.
Hi POD,
Yes they do - particularly the cheap ones.
If the door in question is one that is not opened/closed regularly, this can also contribute to the switch failing.
As you say - a cheap and easy fix - just make sure you put the system in engineer mode first (or deafen everyone when you break the tamper circuit!)
If the sensor is on an EOL circuit rather than double pole, I would be tempted to change the resistor at the same time.
ETA: If the sensor is recessed into the door frame rather than a surface mounted one, check for damp in the recess - and treat as necessary.
Yes they do - particularly the cheap ones.
If the door in question is one that is not opened/closed regularly, this can also contribute to the switch failing.
As you say - a cheap and easy fix - just make sure you put the system in engineer mode first (or deafen everyone when you break the tamper circuit!)
If the sensor is on an EOL circuit rather than double pole, I would be tempted to change the resistor at the same time.
ETA: If the sensor is recessed into the door frame rather than a surface mounted one, check for damp in the recess - and treat as necessary.
Edited by Meeja on Tuesday 22 December 14:10
ok thanks. I wish I could remember the engineer code, I've got it written down somewhere...
I'll probably just replace the thing. I did wonder though, as its in a kitchen, if there wasn't a bit of moisture in there that had been freezing.
I'll open it up tomorrow (if I find that code)!
I'll probably just replace the thing. I did wonder though, as its in a kitchen, if there wasn't a bit of moisture in there that had been freezing.
I'll open it up tomorrow (if I find that code)!
For the sake of a few quid, I would replace the sensor/switch as a matter of course
If you can't find the code, then depending on the panel, you should be able to pop the cover of the a PIR detector to trip the tamper, punch in your normal user code to silence the alarm, and then work on the door contact without re-tripping the tamper
Once finished, refit the PIR cover and enter your code into the panel again to clear down.
Depending on the make and model of panel, I may have an installation manual which would allow you to default the panel settings, and reprogramme (so you would be able to create a new engineer code)
Happy to help offline if needed (out of the public forum) - drop me a line via profile if needed
If you can't find the code, then depending on the panel, you should be able to pop the cover of the a PIR detector to trip the tamper, punch in your normal user code to silence the alarm, and then work on the door contact without re-tripping the tamper
Once finished, refit the PIR cover and enter your code into the panel again to clear down.
Depending on the make and model of panel, I may have an installation manual which would allow you to default the panel settings, and reprogramme (so you would be able to create a new engineer code)
Happy to help offline if needed (out of the public forum) - drop me a line via profile if needed
If you have a contact like this, which i suspect you will
the zone is on the silver screws and the tamper, if it has one and doesn't use end of line resistors, will be 2 twisted cables connected to one of the bronze screws. So long as you don't untwist the 2 cables and replace like for like, you shouldn't set off a tamper alarm.
If you have a contact that has tamper switch like this
or uses EOL resistors, then you may have a problem depending on the panel you have.
Got any piccies of it?
the zone is on the silver screws and the tamper, if it has one and doesn't use end of line resistors, will be 2 twisted cables connected to one of the bronze screws. So long as you don't untwist the 2 cables and replace like for like, you shouldn't set off a tamper alarm.
If you have a contact that has tamper switch like this
or uses EOL resistors, then you may have a problem depending on the panel you have.
Got any piccies of it?
Edited by Westy Pre-Lit on Wednesday 23 December 17:53
Its ok I've done it now, the sensor doesn't have a tamper circuit, but the wires were shorted to trigger the tamper alarm if the cable was cut.
I've popped a new reed switch in there, and will see what happens. Didn't need the engineer code but I got it anyway, so reprogrammed the message on the ctrl unit which has been the same for about 8 years!
I've popped a new reed switch in there, and will see what happens. Didn't need the engineer code but I got it anyway, so reprogrammed the message on the ctrl unit which has been the same for about 8 years!
The cables shorted out at the sensor is the tamper circuit - that is correct, and unbelievably used to meet regs.
These days, decent surface contacts have tamper protection on the actual reed switch, so that you cannot access any of the wiring without tripping the tamper circuit - the downside is that it makes the actual unit much larger. Helps with double pole wiring (which is what yours is) - but highly unlikely that you would suffer from someone tampering with your wiring in a domestic property.
In the (very) old days, the door contacts were recessed, and were hard wired - and you had to fit a tamper proof junction box on the door frame where the cable from the panel would meet the hard wiring from the sensor.
EOL wiring is much better, as the risk of tampering undetected is greatly reduced, and means that you can run less cables around a building (or in reality, run the same amount of cables, but have spares for expansion and fault repairs) - as the tamper and alarm circuits are the same, and each sensor only uses two wires.
Anyway - glad you got it sorted - hope it solves the problem!
ETA: just a thought, but if it is an eight year old system, has the battery in the panel been changed? - If not, I would replace it when you have a bit of spare cash (£20 or so) and five minutes.
These days, decent surface contacts have tamper protection on the actual reed switch, so that you cannot access any of the wiring without tripping the tamper circuit - the downside is that it makes the actual unit much larger. Helps with double pole wiring (which is what yours is) - but highly unlikely that you would suffer from someone tampering with your wiring in a domestic property.
In the (very) old days, the door contacts were recessed, and were hard wired - and you had to fit a tamper proof junction box on the door frame where the cable from the panel would meet the hard wiring from the sensor.
EOL wiring is much better, as the risk of tampering undetected is greatly reduced, and means that you can run less cables around a building (or in reality, run the same amount of cables, but have spares for expansion and fault repairs) - as the tamper and alarm circuits are the same, and each sensor only uses two wires.
Anyway - glad you got it sorted - hope it solves the problem!
ETA: just a thought, but if it is an eight year old system, has the battery in the panel been changed? - If not, I would replace it when you have a bit of spare cash (£20 or so) and five minutes.
Edited by Meeja on Wednesday 23 December 21:16
Most of the backup batteries in the alarm trade are Yuasa branded and havge a useable life of up to five years - sometimes less.
Certainly worth changing every three years or so to be sure.
Last thing you want is the alarm going off in the event of a power failure because the battery can't maintain the system!
Certainly worth changing every three years or so to be sure.
Last thing you want is the alarm going off in the event of a power failure because the battery can't maintain the system!
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