EOL resistors?
- Thread starter RogueOne
- Start date
A set of EOL resistors is included with the M1.
EOL resistors make it possible for the alarm panel to monitor the integrity of the wiring for each zone circuit. Without EOL resistors, the panel would normally see a short circuit when the contact switch for a door or window is closed, and an open circuit when the door or window is open.
The problem is that if the wiring develops a short between the wires for some reason, the alarm panel can no longer tell when the door/window is opened. It would look closed all the time, and someone could walk right in and the alarm would never go off.
With the EOL resistor, a short would look different from a closed or open contact switch, allowing the panel to report a trouble condition.
EOL resistors are also used to monitor the integrity of wiring for smoke detectors and siren/bell circuits. These are sometimes different value resistors from the zone EOLs.
Sometimes, an installer will place the EOL resistors at the panel, rather than at the far end of the zone wiring. Placing them at the panel is the wrong way to do it, and they provide no supervision that way. Always put them at the far end of the wire, at the last contact in the zone.
Here's more information:
http://security.livewatch.com/forum-ref/what-are-end-of-line-resistors-and-do-i-need-them-on-my-alarm-system
EOL resistors make it possible for the alarm panel to monitor the integrity of the wiring for each zone circuit. Without EOL resistors, the panel would normally see a short circuit when the contact switch for a door or window is closed, and an open circuit when the door or window is open.
The problem is that if the wiring develops a short between the wires for some reason, the alarm panel can no longer tell when the door/window is opened. It would look closed all the time, and someone could walk right in and the alarm would never go off.
With the EOL resistor, a short would look different from a closed or open contact switch, allowing the panel to report a trouble condition.
EOL resistors are also used to monitor the integrity of wiring for smoke detectors and siren/bell circuits. These are sometimes different value resistors from the zone EOLs.
Sometimes, an installer will place the EOL resistors at the panel, rather than at the far end of the zone wiring. Placing them at the panel is the wrong way to do it, and they provide no supervision that way. Always put them at the far end of the wire, at the last contact in the zone.
Here's more information:
http://security.livewatch.com/forum-ref/what-are-end-of-line-resistors-and-do-i-need-them-on-my-alarm-system
RAL
I've read that the resistor should not only be at the sensor at the farthest point of the zone but I have also read that it should be on the common side of that sensor. Can you explain how it can make any difference which side of the sensor the resistor is located on?
Mike.
EDIT
I'm talking about three state zone with the resistor in series.
I've read that the resistor should not only be at the sensor at the farthest point of the zone but I have also read that it should be on the common side of that sensor. Can you explain how it can make any difference which side of the sensor the resistor is located on?
Mike.
EDIT
I'm talking about three state zone with the resistor in series.
Ground fault. If on the high side of the zone, a ground could bridge and complete the circuit. Common occurrence at a local university here when they were running 3 state EOLR's. Ground fault or a moderate resistance bridge to ground (aluminum extrusions with fished conductors are notorious) can cause enough for the loop to set up but have a high resistance ground fault. Also depends on the reference your system has.mikefamig said:
Depends on the nature of the fault. If the resistor is on the high side, you could have a short to ground that completes the circuit, such as the aluminum extrusion of a storefront and building steel....the variable is whether or not the low side of the zone gets a ground reference or not. Same issues occur on fire alarms with cabling. Two ground faults essentially equals a short circuit on the same loop. If you have a powered detector, that's even worse as you have 2 locations you can get a ground or external reference.
Think of it on a zone with multiple contacts wired in series. If you have wiring between them and a short on the high leg to ground, you effectively shunt all the downstream contacts and the panel never sees them.
Back in the old Logiplex access control days (and security systems) at a local university, they had multiplex zones on a single cable pair. Enough high resistance faults or a ground or two, you could open up one of the zones and the panel would never see it (part of why I hate zone "doubling" on panels).
Easiest way would be to think of it in automotive terms, where is the ground of a typical car located? Is there one or can I pick it up almost anywhere?
Think of it on a zone with multiple contacts wired in series. If you have wiring between them and a short on the high leg to ground, you effectively shunt all the downstream contacts and the panel never sees them.
Back in the old Logiplex access control days (and security systems) at a local university, they had multiplex zones on a single cable pair. Enough high resistance faults or a ground or two, you could open up one of the zones and the panel would never see it (part of why I hate zone "doubling" on panels).
Easiest way would be to think of it in automotive terms, where is the ground of a typical car located? Is there one or can I pick it up almost anywhere?
OK I was thinking of a single sensor on the zone and couldn't see any difference in whether the resistor was on the high side or the common side of the sensor.
Having several sensors on one zone complicates things and I can't really imagine how the elk would interpret a ground fault that occurs somewhere in the middle of them. I CAN see how it would be difficult to troubleshoot, especially if it was a high resistance fault to earth.
Mike.
Having several sensors on one zone complicates things and I can't really imagine how the elk would interpret a ground fault that occurs somewhere in the middle of them. I CAN see how it would be difficult to troubleshoot, especially if it was a high resistance fault to earth.
Mike.
vacationer
Member
Just wanted to "piggyback" and ask a few questions (newb so still trying to learn):
1. I will assume according to RAL's initial post that even if you don't have EOL resistors as part of your system the system itself will still "work" it just won't be able to tell if a door/window is open if the wiring develops a short (is this the same thing as a break in the wiring or something)? I was just asking because I am fairly confident my system does not have EOL resistors and it "appears" to be working....just wanted a real life home environment example of how it could potentially stop working because I do not have EOL resistors.
2. When you install EOL resistors and say you are wiring windows....I have read you should not put them on the panel end but rather the door/window contact end. Well my question is, how the heck would you install an EOL resistor on a window contact and still hide it from being seen yet still get to it if something goes wrong with it in the future and it needs to be replaced?
Sorry for the newb questions
1. I will assume according to RAL's initial post that even if you don't have EOL resistors as part of your system the system itself will still "work" it just won't be able to tell if a door/window is open if the wiring develops a short (is this the same thing as a break in the wiring or something)? I was just asking because I am fairly confident my system does not have EOL resistors and it "appears" to be working....just wanted a real life home environment example of how it could potentially stop working because I do not have EOL resistors.
2. When you install EOL resistors and say you are wiring windows....I have read you should not put them on the panel end but rather the door/window contact end. Well my question is, how the heck would you install an EOL resistor on a window contact and still hide it from being seen yet still get to it if something goes wrong with it in the future and it needs to be replaced?
Sorry for the newb questions
vacationer said:
Without the resistor the system can only sense two states, open=0.0 vdc and closed=~13.8 vdc. Adding the resistor adds a third state. open still = 0.0 vdc but closed = ~7vdc due to the 2.2k ohm resistor being in series in the circuit.
Adding a third state allows the Elk to detect if the circuit is shorted. An open sensor still = 0.0vdc, a normally closed zone will = ~7vdc while a shorted closed circuit will = 13.8 vdc.
You do not need to use eol resistors. Elk RP2 allows you to configure the zone as either with or without depending on whether or not the resistors exist.
vacationer said:2. When you install EOL resistors and say you are wiring windows....I have read you should not put them on the panel end but rather the door/window contact end. Well my question is, how the heck would you install an EOL resistor on a window contact and still hide it from being seen yet still get to it if something goes wrong with it in the future and it needs to be replaced?
Sorry for the newb questions
Good question. I struggled with this and finally came up with a splice that fit nicely in the 3.8" hole in the window sill. It involves using sensors with screw terminals, single stranded wire and neat splices with heat shrink tubing.
RogueOne said:
Which sensors require EOL resistors varies with the alarm panel. On some panels, if you use an EOL resistor on one zone, then you must use them on all zones.
On the Elk M1G, you can configure them zone by zone and use them only where you want.
You also need EOL resistors on any smoke detector zones. For 2-wire smokes, you need to use an 820 ohm resistor, rather than the 2.2k you would use on other zones. 4-wire smokes use 2.2k.
The Elk keypads connect to the data bus, which is different from a zone circuit. The data bus uses terminating resistors rather than EOL resistors. The data bus needs to have exactly 2 terminating resistors on it. These are configured using jumpers on the M1G panel and the keypads (also zone expanders and the M1DBH, if you have those).
In simple terms, the two terminating resistors go at the two endpoints of the data bus. Understanding what an endpoint is is the tricky part.
For a single keypad and no other data bus devices, you put a jumper on JP3 on the M1G and also on the one keypad.
Refer to the manual for more information on this, and how to configure the jumpers for other situations.
