Class "E" FA..Spkr/Strobes

[horsegoer]

I have some speaker strobes that are labeled to be wired A&B loop. I understand this to be alternating wiring. Can someone give me an overview on how these are wired. Do you use 14/2 FA cable. Just want to know the RIGHT way to wire these. And I know you guys on here are very knowledgeable and good at your craft.

Thanks

[mdshunk]

You sure they aren't dual marked? I'm not sure how you'd wire class A and class B to the same horn/strobe.

[infinity]

He's asking about A and B alternating loops. Not the same as Class A systems. Generally you would have each adjacent device on a different zone than the one next to it. So a long corridor with say 3 devices would have the first device on loop A, the second on loop B, and the third on loop A, etc.

[peter d]

Do you use 14/2 FA cable.

At the minimum you need to use 14/2 for notification loops. You may need to upsize to 12/2 for longer loops.

[mdshunk]

He's asking about A and B alternating loops. Not the same as Class A systems. Generally you would have each adjacent device on a different zone than the one next to it. So a long corridor with say 3 devices would have the first device on loop A, the second on loop B, and the third on loop A, etc.
Cool. I've never seen that configuration.

[peter d]

Cool. I've never seen that configuration.

Cool. I've never seen someone who's never seen that configuration.

[mdshunk]

Cool. I've never seen someone who's never seen that configuration.Allow me to introduce myself...

[infinity]

Cool. I've never seen that configuration.


Judging from his location, this is SOP for NYC installations. If one zone fails the other will still operate every other device. Depending on the length of the runs we typically use #16 for speakers and #14 for strobes. Longer runs with many devices may require #14 and #12 conductors respectively.

[horsegoer]

Infinity are you in NY? Ok, I understand and thought it was done that way. One other question. So a speaker strobe on requires on cable not one 14/2 for the strobe and one 14/2 for the speaker?

Thanks guys....PeterD and MD that was a great "nice to meet you"..lol

[LarryFine]

Cool. I've never seen someone who's never seen that configuration.Cool. I've never seen someone who's never seen someone who's never . . . :grin:

[infinity]

Infinity are you in NY? Ok, I understand and thought it was done that way. One other question. So a speaker strobe on requires on cable not one 14/2 for the strobe and one 14/2 for the speaker?

Thanks guys....PeterD and MD that was a great "nice to meet you"..lol


I'm familiar with how things are done there. Yes the speaker and strobes each require a separate cable. For a combination device that is part of a loop that means you could have 4-2 wire cables terminating at the one device. SPK-IN/SPK-OUT STB-IN/STB-OUT

[iwire]

I'm familiar with how things are done there. Yes the speaker and strobes each require a separate cable. For a combination device that is part of a loop that means you could have 4-2 wire cables terminating at the one device. SPK-IN/SPK-OUT STB-IN/STB-OUT

I agree, the City of Boston also expects the circuits to be run in the same 'A, B, A, B fashion.

[horsegoer]

So it 14/2 alternating for the strobe portion and 14/2 alternating for the speaker portion?

[infinity]

So it 14/2 alternating for the strobe portion and 14/2 alternating for the speaker portion?

That would be one way of doing it. You also can use a 4 conductor cable. One cable in and one cable out. The conductor size is usually determined by the fire alarm vendor so it's their call as to whether or not #14 is good for both speakers and strobes.

[horsegoer]

Great got it. From an installation point of view. I gthin one cable(4 cond) would make more sense and be a bot less labor intensive????????? Infinity are you based in NY?

[infinity]

Great got it. From an installation point of view. I gthin one cable(4 cond) would make more sense and be a bot less labor intensive????????? Infinity are you based in NY?

I'm in NJ. One disadvantage of 4 conductor cable is that areas that have strobe only devices will now have the speaker conductors brought to those locations also. This could waste a lot of wire/labor and add many splices to your system.

[horsegoer]

Good point INF. So what would happen to the extra pair brought to a strobe only? You only suppose to term. the 2 pair for the strobe at that location, right?

[infinity]

Good point INF. So what would happen to the extra pair brought to a strobe only? You only suppose to term. the 2 pair for the strobe at that location, right?


Yes, the other pair (speakers) would get spliced through to the next device with 150 deg C wire nuts.

[brennan]

Yes, the other pair (speakers) would get spliced through to the next device with 150 deg C wire nuts.

Why the 150 deg C wire nuts?

[infinity]

Why the 150 deg C wire nuts?


I'm not sure if it's an NFPA requirement or a local requirement. The ones we use are small black wirenuts made by Ideal.

[brennan]

Is that on all FA splices or what?

[mdshunk]

I'm not sure if it's an NFPA requirement or a local requirement. The ones we use are small black wirenuts made by Ideal.
I use those for changing ballasts in HID fixtures. They're the only one's that last without turning to crumbles.

[peter d]

Is that on all FA splices or what?

Must be a local rule. It's not an NFPA 72 rule, that's for sure.

[horsegoer]

So I just want o make sure I have this right. If I have 10 spkr/strobes in area that is calling for "A&B" circuiting. I guess I can wheel of the total footage hitting each device and bring 14/4. that will cover the speaker portion then bring the same footage of 14/4 for the strobe. If I do it with 14/2 to 1,3,5,7, etc. device say 300' then say another 12/2 to 2,4,6,8, devices. Is either way correct?

[infinity]

So I just want o make sure I have this right. If I have 10 spkr/strobes in area that is calling for "A&B" circuiting. I guess I can wheel of the total footage hitting each device and bring 14/4. that will cover the speaker portion then bring the same footage of 14/4 for the strobe. If I do it with 14/2 to 1,3,5,7, etc. device say 300' then say another 12/2 to 2,4,6,8, devices. Is either way correct?


You will need a 14/4 for each of the A & B loops. The first 4 wire cable will contain say 1 pair for SPK a and 1 pair for STB A The next device on the B loop will require a 14/4 with 1 pair for SPK B and 1 pair for STB B.

[brennan]

I would use shielded wire for the speakers.

[infinity]

I would use shielded wire for the speakers.



I would only use the type of wire that is specified by the fire alarm vendor. I seen specs that call for shielded and others that say no shielded permitted.

[iwire]

I would only use the type of wire that is specified by the fire alarm vendor.


I agree, that is the kind if manufacturer recommendation I would follow to the letter.

The last voice evac system (Siemens) I helped with it was shielded for the strobes and non-shielded for the speakers. :-?:-?:-?

It was a MC job so it was all more or less shielded but we would not be able to get a single cable with one pair 14 AWG shielded and one pair 16 AWG non-shielded.