Elk wiring question

[apostolakisl]

If you put a 500 ohm resistor in series at the panel with each zone, you will end up with the following:

Short 2.8v (A short in the wire out in the home bypassing the 1000 ohm eolr but not the 500 one on the panel)
Secure 5.9v (Zone feeds through both the 500 ohm at the panel and the 1000 ohm eolr)
Open 13.8v (There is no short and the door/window contact is open)

Elk range is
0-3.9 short
4.0-8.8 secure
8.9-13.8 not secure

The numbers from putting a 500 ohm resistor in series will allow you still maintain eol resistor benefits without tearing open your walls to find the resistors.

If you use a 1200 ohm resistor in series at the panel, should a short occur (screw through a wire, bypassing EOLR but not 1200 one at panel), the system will see 5.2v, which it will erroneously register as a secure zone.

You do run the risk of the 5.9v "secure" voltage level being kind of close to 4.0 and it is possible the value may drift for some reason and erroneously report a short. You would need to hook it up and see just how stable it is. In my experience, I have never seen an eolr secure zone differ from the expected 7.4v by more than .2v.

 

[Del91574]

So, how often do we hear of tampering related to residential contacts? I mean, if anyone has seen that happen, please - share your story. It seems like overkill in a residential environment.

That said, for testing - I do believe in walk tests - do them often! It can be as simple as keeping your system on Chime and making sure you get the appropriate alerts when you open the doors and windows. Because of kids, I always make sure my door/window contacts are working as intended.

Much less a tampering issue, however I have seen it happen with security screens and someone attempting to take a lighter to the leadwire/plug to short out the screen so it could be removed without setting the alarm off, same thing happened at a couple of residences around here where it turned out to be a memeber of a crew, can't remember if it was the cleaners or a trade. We've had some dummy phone drops that we installed as tamper loops up the side of the residence to generate a line cut signal first over the LRR before the panel saw the telco go away get monkeyed with, and it wasn't the telco that did it, as the NID and weatherhead were tagged. We've also seen people monkey with tamper loops/magpulls that were connected to movable equipment on a site. We've had venting magnets moved and their polarities "flopped" so the magnets as they sat on the window N-S N-S acted as a big magnet and gave the window a huge dead area where it could be opened up without setting off the alarm.

Tamper isn't the main importance, however we have issues with wire damage from animals chewing wires, such as squirrels and mice as well as wiring damaged by other means....carpet and hardwood installers, homeowners by accident with a closet run....and a lot of outbuildings where the wiring is not or was not installed in conduit. I've done takeovers of "perfectly" working systems and fixed fire alarm supervision issues (T-taps) and other wiring issues to find staples through wires, crushed conductors and chewed cables. I typically cut the pieces out and hand them to the homeowner and provide an explanation, which when it's proven their system wasn't working properly or sometimes, zones were not working at all.

Walk tests are great, but in reality, how many end users do them on a residential system?

 

[frankv]

Thanks for all the info, lots to digest. Sounds like I could live with the existing EOLRs or try adding at the panel and test the results for extra protection, but basically it should work. Replacing the existing ones is not really a viable option for some of them.

Honestly didn't expect that many options and implications, definitely learned from this thread!