4 wire smokes and EOL's

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

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

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

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.

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

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.

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.

Some of those old building can be a real pain. I did a number of really old mansions in CT years ago and they could be a challenge.

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

I can only think of two possibilities

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