With the M1 gold, and door/window sensors, when would you need EOL resistors?
- Thread starter ghurty
- Start date
tmbrown97
Senior Member
You don't need them - they're an extra layer of protection if you *want* them.
They help protect against a short in the wires that you don't know about, or the theoretical case where someone would short out the sensor wires before the sensor so they could open a door/window unimpeded (highly unlikely in a residential scenario).
They're rarely used in residential, if any security systems.
They help protect against a short in the wires that you don't know about, or the theoretical case where someone would short out the sensor wires before the sensor so they could open a door/window unimpeded (highly unlikely in a residential scenario).
They're rarely used in residential, if any security systems.
wuench
Senior Member
And they make for a more complicated and messier install for things like door and window sensors. At least for amateurs like me.
They are easier to use in motion detectors though since you usually have screw terminals to work with.apostolakisl
Senior Member
Without eol resistors the alarm has no way of knowing about a purposeful or accidental short in the wire.
With eol resistor in place there are only two states that the alarm should see, 2200 ohms, and open circuit. If a screw gets put through the wire or a mischievous service person is in your house decides to short out a zone for future access to your home, the alarm will see a "short" condition and report fault. Also, if a short occurs, the alarm reports it immediately. So if you are hanging a picture and put a nail through the wire, you will know right away and be able to pinpoint the problem. If you didn't get that immediate message, you might not discover the problem for months or years and have no clue when/where the damage was done.
If you don't have eol resistor mode on, the alarm will interpret a short as a closed window/door, since electrically they are identical.
With eol resistor in place there are only two states that the alarm should see, 2200 ohms, and open circuit. If a screw gets put through the wire or a mischievous service person is in your house decides to short out a zone for future access to your home, the alarm will see a "short" condition and report fault. Also, if a short occurs, the alarm reports it immediately. So if you are hanging a picture and put a nail through the wire, you will know right away and be able to pinpoint the problem. If you didn't get that immediate message, you might not discover the problem for months or years and have no clue when/where the damage was done.
If you don't have eol resistor mode on, the alarm will interpret a short as a closed window/door, since electrically they are identical.
drvnbysound
Senior Member
... and becase of them being identical with regards to electrical testing, that short will only be detected if the resistor is installed directly at the sensor.
If you install the EOL resistor at the panel, and the wire is shorted in the wall somewhere (e.g. nail) the panel will still read the EOL resistance and show that the door/window is closed, regarless of its actual state.
tmbrown97
Senior Member
Lou's absolutely correct... yet still they're almost never found in a residential install.
I'm pretty careful about who I let in my house - they're generally not people who would be tampering with my security system... plus I keep chime on and I always pay attention to the beeps when I open a door or window - kind of a continuous walk-test.
One per zone.
I agree, and I don't know why they aren't used in residential systems -- it is just not that big a deal to put them in. It does help if you know how to solder, but there are solderless connectors you can use, and with door and window sensors you'll have to use something regardless to connect the sensor leads to the cable.
I will point out something... I don't know how the Elk does it, but with an HAI system, a shorted security zone is treated as open, and it results in an alarm condition (rather than a trouble condition) if the alarm is armed in the proper mode for that zone.
drvnbysound
Senior Member
Regarding sensor leads connecting to the security cable .... none of my sensors had wire leads of their own. My sensors simply had set screws into the terminal block to fasten the wires directly to the sensor. I wasnt a fan of having the resistors exposed (if they were directly attached to the sensor) and I wasnt crazy about soldering them in-line shortly behind that inside the wall (possibly creating a failure point inside the wall, which wouldnt be easy to repair if something were to go wrong). Having said that, I am one of the residential people who decided not to install them.
Interesting... all of the door and window sensors I've seen have had leads. I solder the resistor in line with one of the leads, and then cover the whole thing with heat-shrink tubing. The other lead gets soldered directly to the corresponding wire and it also gets heat shrink. That way, no shorts behind the wall and moisture won't effect it. I always leave some slack wire in the wall so that I can pull the sensor back out if I need to. For sensors mounted flush with the door casing, I secure and seal them in with silicone caulk; if I need to, I can cut the silicone away with an exacto knife and pry the sensor back out. The sensor itself is a lot more likely to fail than the resistor is.
drvnbysound
Senior Member
Yeah, mine are similar to this:
apostolakisl
Senior Member
Yeah, mine are similar to this:
So with that kind of a connector you can screw down your resistor then solder the other end to one lead (makes no diff which lead) and screw down the second lead directly to the sensor. Of course if the wire doesn't immediately dive into a hole where the resistor is thus hidden, you may want to put a short length of wire in there to move the resistor far enough away that it gets hidden in the window frame or door frame.
The important thing is use only 1 eol resistor per zone and put it at the end of the run. So if you have more than one sensor on a zone, just put the resistor at or near the last one.
And you are right about that stuff, but, I have windows in my house that I have never opened in the two years I have lived here. So, I would never know if one of them had a bad wire but for using eol resistors.
drvnbysound
Senior Member
Yeah, unfortunately, mine were pre-wired, and the drywall contractor didn't leave any play room in the wiring. They way they installed the drywall didnt leave any room for the wiring to be pushed back into the wall. They basically notched the back side of the drywall and pressed the drywall against against the window frame, allowing the wire to pass through the notched cut. So the wire is basically pinched between the stud (where I drilled the hole and the wire feeds through) and the drywall. So I had the distance from the drywall, to the sensor to install a resistor (and I just chose not to):
apostolakisl
Senior Member
While doable, that would be a PITA.
