4 wire smokes and EOL's

[CH®IS]

Ideally, you'd have only one smoke on a zone. Unfortunately, I didn't
install todays disaster where there are 9 smokes on 2 zones. Are zone
expanders really that expensive?

Anyway... I'm now wondering about how to do resistors correctly when you
have more than one smoke (either daisy chained or home run) on a zone. Do
you have a resistor in each smoke, or just one at the end. Being a normally
open contact (DSC 5010), it would make sense to have them in each smoke, but
I've seen them installed both ways.

- Chris

 

[G. Morgan]

Anyway... I'm now wondering about how to do resistors correctly when you
have more than one smoke (either daisy chained or home run) on a zone. Do
you have a resistor in each smoke, or just one at the end. Being a normally
open contact (DSC 5010), it would make sense to have them in each smoke, but
I've seen them installed both ways.

All the wiring goes in parallel to the last detector, with a single resistor
at the last smoke. Also, you may need a power supervision relay if the smoke
doesn't have it built in.

This is really basic stuff, it sounds like you don't have the experience to be
working on a fire alarm reliably. Please have someone who knows what they are
doing inspect your work.

 

[CH®IS]

All the wiring goes in parallel to the last detector, with a single
resistor
at the last smoke. Also, you may need a power supervision relay if the
smoke
doesn't have it built in.

This is really basic stuff, it sounds like you don't have the experience
to be
working on a fire alarm reliably. Please have someone who knows what they
are
doing inspect your work.

This would make sense, as I don't do fire alarms.

Although now I see why you'd just have one resistor. I was thinking since
it's an "open circuit", it's open, but it's not. However, if they're all
home run, there's no supervision for the rest of the smokes on that zone.

- Chris

 

[G. Morgan]

Although now I see why you'd just have one resistor. I was thinking since
it's an "open circuit", it's open, but it's not.

To the extent of the EOLR's value I guess you could say it's not "open"

However, if they're all
home run, there's no supervision for the rest of the smokes on that zone.

You can do it that way by running 6 pair cable to each.

 

[G. Morgan]

4-Conductor is enough for 2-wire smokes and 8-conductor will handle 4-wire
models unless you're running auxiliary relays or something.

Right. I said 6 conductor because I thought just about every 4-wire detector
has a built in power supervision relay. It's been years since I've even
messed with 4wires though.

However, there
*might* be an issue with the inspector. Some I know mistakenly confuse the
requirement from old, Class "A" circuits that the "return" run be separate as
prohibiting this wiring scheme. I think they're wrong but there's that little
clause we all know and love, "The interpretation and application of this code
shall be subject to the discretion of the authority having jurisdiction." :^)

I've never had an inspector look that close. I would only do it in a retro or
repair type situation. I remember wiring a really old country club clubhouse
that had so many additions and modifications we had to use 4 conductor for the
2-wire smokes because many of the wireshots were in such tight spaces.

 

[CH®IS]

That is exactly right, Chris. So, unless you have lots of spare zones
available, you will want to wire the smokes to a single zone (in the
manner Graham suggested). Since smoke detectors have latching LEDs to
tell you which one is in an alarm state, it's OK to have them all in a
single zone or, perhaps, one zone per major area of the premises. We used
to run one fire zone per floor on residential jobs in Connecticut. That
way, the homeowner could see on the keypad if the problem was in the
basement, first or second floor.

In this case I don't have any spare zones, and there are only a few homerun
smokes anyway. However, it's listed on the keypad and in the file (never
trust the file unless i installed it and wrote it) that there's a zone for
the main floor smokes, and a zone for the basement smokes. Seems simple
enough, except that there are a few smokes on the main floor that have
resistors in them, but not all of them.

Of course this has to be a busy dentist office with no room to work and no
way to politely be making that much noise testing smokes. And of course
it's the type of building that seems to be renovated so often that it just
never stops being renovated. As soon as one project is done, another part
of the building gets rebuilt.

But really... 9 smokes in probably 3000 square feet? What do dentists have
on hand that's so flammable (other than the helium tank for the balloons)?

- Chris

 

[Jim]

...


In this case I don't have any spare zones, and there are only a few homerun
smokes anyway. �However, it's listed on the keypad and in the file (never
trust the file unless i installed it and wrote it) that there's a zone for
the main floor smokes, and a zone for the basement smokes. �Seemssimple
enough, except that there are a few smokes on the main floor that have
resistors in them, but not all of them.

Of course this has to be a busy dentist office with no room to work and no
way to politely be making that much noise testing smokes. �And ofcourse
it's the type of building that seems to be renovated so often that it just
never stops being renovated. �As soon as one project is done, another part
of the building gets rebuilt.

But really... 9 smokes in probably 3000 square feet? �What do dentists have
on hand that's so flammable (other than the helium tank for the balloons)?

- Chris-

I can only think of two possibilities

It's either got to be their egos or their money.