OK to use 14 ga. wire for smokes?

[JonR]

My electrician ran wire for line-voltage smokes on the upper floor before I could get the inspector to approve my use of System Sensor 4-wire smokes. Now I either need to use the 14 ga. wire that's up there or rip it out and run the 18 ga. FireWire I've already purchased. Although the smoke install instructions indicate that the terminals will accept 14 ga. wire, will it be a problem getting it onto the Elk? Are there any other issues to consider? The existing wire is all bundled with all the other line voltage wire so I don't know if interference would be a concern.

Thanks,
JonR

 

[Sandpiper]

Isn't the #14 wire short on conductors? (You mentioned using 4 wire smokes).

 

[Spanky]

Functionally, the 14 ga. wire is no problem. It is lower resistance than the 18 ga wire.

You need it series wired for the smoke detectors to have an EOL resistor at the end of the circuit. "Star" wiring will not give you supervision of the fire circuit.

If you have only 3 conductors, the negative of the +12Vdc is the same as the negative on the smoke zone input. They connect together in the M1 Control.

 

[JonR]

Thanks for the info. I believe the wiring that's up there is 4-conductor but I know there are at least three.

Another wrinkle is that the existing wiring is not run back to the panel so is it OK if I use 18 ga. to run from the panel to the first smoke and then use the 14 ga. that's already in place?

JonR

EDIT: Clarified first sentence. A visit to the site verifies that the wire has 4 conductors but one is a bare ground wire.

 

[CORT]

Another wrinkle is that the existing wiring is not run back to the panel so is it OK if I use 18 ga. to run from the panel to the first smoke and then use the 14 ga. that's already in place?

You may want to run the 14 ga wiring to your panel just in case you decide to sell the house and take your Elk system with you. This way you have the option of converting back to the standard 120V connected smoke detectors at a later date.

 

[Steve]

I'm assuming you are using 4 wire detectors because you already have them? - Because doesn't daisy chaining them negate the benefit of 4 wire smokes - zoning?

 

[Spanky]

You can daisy chain 4 wire smokes the same as two wire. When daisy chaining, you do not get the individual fire zone annunciation like having a 4 wire smoke on an individual zone.

 

[CDC]

JonR, were you the post who was trying to get your inspector to permit your use of system smokes? If not, sorry. If so, aren't you are using a polarity reversing relay to sound all your detectors. I would rip out the 14/3 and repull it with the 18/4 FPL cable. It can't be that much cable. It would suck to have the insepctor bust you later. If you leave the 14/3, be sure to remove it from the last box that would be energized with 120v to the first box with the 12v smoke. You don't want someone to be able to make a joint in that box and put 120v on your system. And again your inspector may want to see "red" fire cable that identifies it as such. I am a contractor, so I would not use the 3-conductor cable with the 4-wire smokes. I just would not take the chance with smoke detectors. I have done it with security devices when left without any other option. Unless the drywall is up, I would start out doing it correctly. JM2C

 

[JonR]

Thanks for the replies. I am in fact the one who was recently able to sell the inspector on the low-voltage smokes so I'm not going to risk it by using the 14/3 wire. We'll pull all of it out and I'll run the 18/4 Fire Wire. The electrical contractor wants written confirmation that the city inspector is agreeing to the low-voltage smokes because in his mind this doesn't meet code. I didn't figure it was worth arguing the point with him - if the inspector is going to sign off that's all that matters.

I'm going to use 4-wire smokes. It was my understanding from another thread that I can zone my smokes while still having a single polarity-reversing module "driving" all of the sounders. I was planning to zone the smokes by floor (= 3 zones) plus separate zones for a couple heat detectors.

For the last week I've been busily pulling wire - I calculated that I'll have just short of a mile's worth of wire in by the time I'm done. Thank goodness for bundled cables!

Thanks,
JonR

 

[Digger]

It was my understanding from another thread that I can zone my smokes while still having a single polarity-reversing module "driving" all of the sounders.

Are you sure about this? It is my understanding that you need a seperate polarity reversal module per zone. All of them would be tripped by the bell output of the panel as the trigger.

You might want to verify this before you get to far into it. I personally like to zone my detectors but I dont use sounders in mine (I have 4 speakers in my house which is VERY loud).

 

[jlehnert]

Yes, it's correct. The reversing relay is only reversing the POWER, not the zones themselves. Since all the power is coming from a single location on the Elk, he only needs a single reversing relay. The only time he would need multiple RRs would be if he had multiple cans, each with it's own power supply (and had smokes going to the cans of course). He DOES need multiple EOL relays, one per zone.

 

[Digger]

Yes, it's correct. The reversing relay is only reversing the POWER, not the zones themselves. Since all the power is coming from a single location on the Elk, he only needs a single reversing relay. The only time he would need multiple RRs would be if he had multiple cans, each with it's own power supply (and had smokes going to the cans of course). He DOES need multiple EOL relays, one per zone. [/QUOTE

OK I agree with that for multiple zones for 4 wire. This would not work with multiple zones of 2 wire (granted ELK only has one but others have multiple).