Re: Can't Mix Smoke Models....really?

[JoeRaisin <joeraisin@xxxxxxxxxxx>]

Point is moot in this case since the 2WT-B is not an audible...

But, what about line reversal?

We used the 2100AT's for quite a while and now install the 2WT-AB's.  We
can't mix them because the line reversal is handled differently.

Nomen Nescio wrote:

> mbbaker said:
>
>
>>Each test is conducted using one
>>make and model of smoke detector.  They don't mix makes and models on
>>the same circuit, therefore, the manufacturer isn't making any
>>warrantees as to the reliability of mixing different types of smoke
>>detectors on the same circuit.
>>
>>The test is described in UL 864 8th edition:
>
>
> The tests you quoted have nothing to do with compatibility.  Operating
> voltage doesn't mean compatibility.  It has more to do with the current
> draw of the two-wire smoke in alarm condition, and whether that increased
> current from a particular smoke is sufficient to cause an alarm on a
> particular control panel's circuitry.
>
> I've looked at a couple of panel instruction manuals, and although they all
> list which two-wire smokes are approved for use with those panels, I don't
> see anything that prohibits mixing those approved smokes on the same
> circuit.  I don't see any logical reason why it should make any difference.
>
> When multiple two-wire smokes are connected on the same zone, the only one
> that counts is the first smoke to go into alarm.  When that first smoke
> trips, it places the entire zone into alarm until manually reset:  the
> other smokes no longer do anything useful at that point.  So, if there are
> three different brands of two-wire smokes on the same zone, and all are
> approved for use with that panel, then any one of those smokes is capable
> of causing an alarm.  Once it does, the other two smokes no longer matter.
> In fact, they probably don't even do anything, since many two-wire smoke
> zones can only supply enough current to power one smoke detector in alarm
> condition.
>
> Finally, if there were any problems with mixing different brands on the
> same zone, it would become obvious during testing.  I'll bet no one has
> ever seen a smoke fail to operate as a result of mixing approved smokes on
> the same zone.
>
> - badenov
>