Easy contact question

[PHJ424]

Starting to run some wiring for the contacts and when my contacts arrived I see that some are marked
Normally Open and Normally Closed.

The package also states if I run more then a few hundered madc thru these that I can fry them out.

So this I have two questions

1, How much current will a DVM run thru the circuit when checking for resistance? I know they use a 9 v battery but never really paid too much attention to the current it pushes thru a circuit when checking resistance? So can you use a DVM to check most magnetic pickup contacts or not?

2. When a contact is labeled Normally Open is that with the magnetic target in range (IE. with the door or window closed and the magnet is actuating the switch?)

I know these are real NuB questions thanks for the assistance.

 

[BraveSirRobbin]

You can use a DVM to check magnetic contacts without a problem (and a good idea for a check of the system once you get them wired up). Most security panels require that the contacts are closed when the magnet is near the contacts (i.e. a door/window is in the closed position).

What security panel are you going to use? Have you considered the pros/cons of EOL resistors, or will you just not use them? Can your panel run in a 'non EOL' mode if you are not using them?

You may also want to view my How-To on this topic as well.

 

[PHJ424]

Thanks for the info Robin.

I am installing an Elk system.

Looks like there will be EOL's in the circuitry and it shows wiring diagrams for using EOL's in detection wiring that has a mix of NC and NO contacts.

Some zones I plan on having only one device on for a few zones. So on those zones with a NO contact and an EOL should work well with the system.

 

[Neurorad]

Brave questions.

I'm researching alarm installs to death before making the plunge.

I'm currently halfway through Low Voltage Wiring: Security/Fire Alarm Systems by Kennedy and Traister.

Some decent info on installs, though ~half deals with the business side of alarm installations. Seems like a textbook for an alarm installer certifying exam prep course.

I over-think everything - sometimes a good thing, other times self-defeating.

 

[felixrosbergen]

Neurad:

I started off that way and tried to plan everything to the nth degree. Now I can actually start a wire run not knowing the full path and just make it up as i go....feels good....hahaha

Almost eveything can be undone....so why worry...

 

[Neurorad]

Almost eveything can be undone....so why worry...

For me, it's mostly about feeling comfortable. I don't like feeling anxious about anything - am I doing it 'the right way'. The more I know about a topic, I'll more likely make 'correct' decisions.

Which alarm products do I need to replace my current system? How do I use a multimeter correctly, without breaking it? Should I buy a reel of 18-2 or 18-4? Won't 22-4 suffice? Can I use some of my current wireless sensors in the new setup, or do I replace them with hardwired?

Which distributed audio system is best for me? Should I risk buying a used system? Can a used server rack suffice in the mechanical closet, if I've never even laid my hands on a rack?

The answers to most of my questions are buried in online forums, and a few select books. Takes a lot of time to learn the details.

Wrong decisions cost money and more time, cause me frustration, and decrease the WAF. I love things to work correctly, and I appreciate exceptional design. If something doesn't work well, I don't want it. I'd much rather do without, than use something that is sub-par.

Sometimes I hate trying to be a perfectionist, but the end result is usually pretty darn good. It helps a lot in my line of work, too. I don't take chances.

Maybe I need to start practicing Buddhism, and learn to accept better.

 

[beelzerob]

Almost eveything can be undone....so why worry...

Once I finally overcame my fear of ripping out and re-patching sheet rock...I was able to sleep at nights, knowing nothing was impossible anymore.

 

[tmbrown97]

heh - it's only time & money, right?

I researched - panicked a lil thinkin' it was over my head, etc - but I had the basic premise of NO/NC contacts already because I've also always installed my own car alarms... Yeah - there's a few extra parts in my Elk part's bin (yeah, it has its own) - and there's a wire run or two I would've done differently, or missed all together, or are unused - but hell - it's all easy enough... and while the manual intimidated me at first, now it just seems insanely simple once you get how it all works.

I will say I'm not a fan of NO - if a wire gets cut you'd never know it unless you explicitly test the zone... though you'd know if there were a short (i'm thinking a window or door that's not opened often). With NC you tend to know if the wire failed or a connection came loose. It's all preference tho. Also, it affects how you'd wire them if there are several on a circuit. With NO you run them in parallel, whereas NC you'd run in series - it could affect how your runs are laid out.