Re: Configuring CO loop on NX8E

[chasbo@xxxxxxxxx]

The disadvantage of using only four conductors in the standard
configured loop with the eol resistor at the CO unit is that if I run
the loop through the contacts of the relay, it will give an alarm
signal when power fails or for some other internal problem unrelated
to the presence of CO.

Therefore you can plainly see that if I wish to avoid sending the fire
department using the configuration in the previous paragraph I can not
make use of the trouble relay contacts -- which is a terrible waste of
good engineering and leaves the homeowner vulnerable to a unit that
someday will faill -- and I and the homeowner won't know about it.



On Fri, 19 Jan 2007 21:16:26 -0500, chasbo@xxxxxxxxx wrote:

>I've used this trick ("borrowing" from the power negative terminal) in
>cases where a customer wanted an additional Motion Detector near an
>existing one, in order to meet my requirement for placing the 2nd MD
>on its own zone.
>
>I've also used the same trick when installing a new CO unit above an
>existing NX8E Keypad.  I feed the CO with 12vdc from the pad, feed the
>negative to the CO relay terminals, and ship the signal back to the
>panel on the unused 4th wire of a standard quad cable (keypad only
>requires three conductors).
>
>To reiterate my original goal, I'd like to use a four-conductor cable
>for alarm and trouble signals for CO Detector configurations, rather
>than run extra cable and use up another zone.
>
>but On Fri, 19 Jan 2007 20:34:47 -0500, "Robert L Bass"
><robertbass1@xxxxxxxxxxx> wrote:
>
>>> CO Detectors are available with an
>>> internal "trouble" relay, which can
>>> be made part of the protective circuit
>>> so that when the relay opens its
>>> closed contacts (as when the power
>>> fails or when the unit fails, etc), a
>>> trouble signal at the control panel is
>>> the result.
>>
>>One problem with wiring the trouble relay on the CO detector into the alarm circuit is that a trouble condition at one detector can
>>block an alarm at a detector farther from the panel.  You might want to consider using a separate trouble loop, wired to another
>>zone.  If you have lots of spare zones at the panel but the wiring is already in place, this can be done using only 4 wires.
>>Connect power for the detector in the usual manner.  If the panel uses a common negative for the zone loops, connect positive to the
>>appropriate power terminals the negative at the detector to "C" on both the alarm and trouble outputs.  Return "NC" from the alarm
>>amd trouble relays on the two remaining wires.