Re: Ademco TUFFTACT rollerball contacts....

["Robert L. Bass" <robertlbass@xxxxxxxxxxx>]

> I don't have a problem using the resistors
> if I must, I just didn't think I had to...

You were correct.  You don't have to, but you may want to consider using
them just the same.  The purpose of the EOL resistor is to supervise the
zone (sensor loop) wiring so that a short or break will always be seen at
the keypads and/or cause an alarm.

Closed circuit devices such as common magnetic door sensors (contacts) would
be wired in series with the resistor.  IOW, the circuit comes from the
panel, passes through the EOL resistor and the sensor, then returns to the
panel.  Instead of seeing 0-2 Ohms on the panel loop the panel looks for say
1000 or 2200 Ohms.  A dead short on a closed circuit zone's wiring would
render the sensor ...er, muzzled and you might not know of it.  A dead short
across a loop that is supposed to show 2200 Ohms can be programmed to
display "Zone Trouble" at the keypads.  Usually the panel will also refuse
to arm unless you bypass the faulted zone.  This makes certain that the user
is aware of the problem in case of an accidental short or deliberate
tampering.

As with all things concerning alarms, you must decide whether the extra
security is worth the minor hassle of using EOL resistors.

> With each zone only having a single contact,
> what do I do with the resistor? Do I simply
> wire it inline on the HI side...

Yes, that or the low side.  It really doesn't matter which side of the loop
you wire it to.  The thing that does matter is where in the loop you install
the EOLR.  Inside the panel they are worse than useless.  The "proper" place
is right next to or (whenever possible) inside the cover of the detecting
device.

> between the panel and the contact? Does
> it need to be protected at all?

Good question.  You should always try to obscure the EOLs.  Inside motion
and glass break detectors there is usually room for an EOLR or three.  Most
techs who use EOLs at the EOL position place them in series with one
terminal of the magnetic contact.  I used to like to wire them between the
NC of the alarm relay and the C of the tamper switch.  This just provided a
convenient place to "splice the EOLR into the circuit.

Many years ago I used to buy sensors with built-in EOLRs directly from
Sentrol (which is now part of GE).  Unfortunately, they stopped making them
that way.  I think you actually can still get them if you pay an exhorbitant
fee for setup and order several $1,000 worth of them (or some such minimum
reuirement).  You might try GRI if you're interested in getting some.
They're a much smaller manufacturer and they tend to be a bit more flexible
than GE.

> ... I was directed towards the rollerballs.
> Is there a better contact option for this
> particular situation?

Opinions vary on this.  I happen to like Sentrol's (GE's) 3005
roller-plunger contacts.  If there's enough room beneath the sash to hide
them from external viewing, you should consider using them.

--

Regards,
Robert L Bass

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