Pete,
It may not all be the installers fault. My 15 year old panel at the farm called out in the owners manual for the resistors to be in the panel. This might be for a different purpose, but I remember that either the NO or NC configuration called for resisters in the panel. My panel did both and didn't care as long as the resistor was put in for the correct configuration.
buckeye and Danno are right in their posts. And the "Hope this makes sense" is right on the money too. All to confusing. That's why I just like to say what I want to have when the door is shut, and I'm sorry that I was not clear and that this doesn't help someone buy a magnetic plunger reed switch.
Cyril, I've been chewing on your post all day. If you had NC swtiches (which would have open contacts when the door is shut) and if you had a system where each zone had a pull up resistor on it, and if the controller did not have programable thresholds (most don't), then putting the EOL on the controller makes it work. You see 2.5 Volts when the door is shut, and ground when the door is open. You can not tell when the wire has been cut. This is why I like the Normally Open ( NO ) switch which has the contacts closed when the door is closed because you can tell when the wire is cut (if your controller supports this). I had one house where the finish carpenter put a nail right through the plunger. It was nice to only have that door bad, and to be able to diagnose it easily.
On my house, I did not use EOL resistors on the doors. The NO switches were just fine, and wiring problems just look like the door is open. Each door is a home run. But the EOL's are fine, and my decision might just be another case of the cobblers children have no shoes.
So on some systems, you need to set up the system with the knowledge of the polarity of each zone (i.e. is it a NO or NC) and the voltages are fixed. Why is it when there are only two possibilities, people manage to make things the most complex :confused2:?
I think this could lead to installers always putting the EOL at the controller because it always works as far as sensing where the door is. And if they blow off the cut wire functionality, life is simple. I have seen the EOL on systems with NO switches at the controller. One industrial site in particular had never ending alarm problems they could never diagnose because they could not tell if the wires were intact. Walking and flying rodent infestation didn't help either. They ended up re-wireing the entire plant (and got a new alarm contractor who did it right).
Realizing I'm long winded, let me try to summarize all this for people who want to make stuff work. IMHO, I would:
1) Use Normally Open (abbreviated NO) door plungers so that when the door was shut the contacts are shorted.
2) Put the EOL resistor at the device, realizing you may need to select what system you have so you know the correct value for the resistor.
3) Solder, tape, and heat shrink because you're burring this thing forever.
4) Home run all doors in your prewiring. You can determine zones later and it's really not that much more work. It will also make it much easier to diagnose wiring problems should they show up later.
5) I'd use an 18 gauge stranded wire with an overall jacket. It's a little more money than the 22 or 24 gauge stuff you can get, but it will stand up to the riggers of construction. You can step on it, hit it with a hammer and pull it and it is still good.
Pete
Edit: Yeah, that cobbler looker yummy !
