Electronic Alarms and Home Security Devices - Basic Alarm System Questions here

The sticky threads were helpful but I still have a few more questions.

First some background on my situation. About 20 years ago I installed a Radio Shack Safe House alarm system. Back then my family was building our own home. We ran alarm wire throughout the house, but not thinking in terms of modern alarms systems we simply hardwired various groups of windows/doors into loops -ie there is no individual wiring for most contact points leading straight back to the control box.

We started with pressure switches on all the windows. I believe this is what would be called "Normally Open". If the pressure is let off one of the switches it closes the circuit and trips the alarm. This method worked well with our hardwired loops. The system never was 100% reliable, but we had good neighbors that could reset the system as needed. At such times we assumed one of the pressure switches was a little flakey. But after all these years it's clear there are now serious problems with the control box and we're looking to upgrade.

We're considering buying a Honeywell system, but not sure how programmable they really are. So here's my questions:

Do modern systems only work with Normally Closed type switches now? Or is this a programmable option? (I noticed some systems support N-Open Fire alarms, but didn't know if this was just an allowed exception.)

On the Honeywell website I see magnetic contacts and embedded magnetic contacts, but isn't not clear if these are NO or NC. Is there any easy way to tell? (Actually, I suppose it may not matter. I've found I can take NC contacts, offset the magnet, and put them into a NO wiring setup. When the window slides open it moves the magnet past the sensor and triggers it closed. Maybe a bit unorthodox, but on the up-side, if anyone sticks a giant magnet against the window hoping for an easy break-in they're going to just complete the circuit themselves. lol)

Oh what I wouldn't give right now to have properly documented all my wiring when I installed the first system. Now, trying to figure out again which windows/doors are on which hardwired loops is going to be lots of troubleshooting work.

So I guess my only question right now is "How programmable are the Honeywell system? Can they use a NO system as is, without me having to rewire everything to NC?"

If you wired the loops with NO switchs in parallel, then current generation systems will let you use that configuration. You have to use zone resistors for this to work. You would be wiring them just as if they were fire zones.

Thanks for the reply. Just a few more questions.

I think I read somewhere, maybe on this boards stickies, that on some systems I have the option to turn off the need for the EOL resistor. Do you think that would be an option I could use for a fully NO system? Or do you think I'd still need the resistor anyway. (I ask because adding that resistor basically means pulling every sensor out of the wall and remembering how I did the original wiring -only a short different between that and just converting to an NC system.)

Still considering my options. I may decided to just go with finding another older Safe House system and replace the existing one rather than a full upgrade to a newer one. If I went the replacement route and I wanted to add a motion detector to it, would such a detector handle an NO system? Are they perhaps switchable between the NO/NC?

Thanks in advance.

No, to use normally open contacts, you _must_ have the resistor across the NO circuit. For a residential system, you can put it at the motherboard end of the circuit and it will work just fine, but it's best to put it across the last NO contact in any given string.