4 wire smoke detector wiring

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Old 01-24-18, 05:45 PM
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4 wire smoke detector wiring

hello,

just bought a new house and the smokes are very old and recommended to be replaced

the house has a vista 20psia (20p equivalent) panel and there are a total of 4, 4 wire smokes installed, 2 445ct and 2 449ct.

after looking at the wires at the smokes, im a little confused...

three of the boxes have 2 sets of 4 wires, red/black/green/white. I am replacing these units with new i3 4wta-b units.

at the end of the line, i have a 445ct. in the box, there is only a single 4 wire set. it is wired as expected, red is the +, black the -, green/white are the alarm loop with a EOL resistor between the terminals with the green and white wires.

i assumed there would be another 4 wire set acting as a return loop, but the resistor was wired onto the terminals of the smoke itself, and there is no red/black wires to return to the panel. i assume there is no power supervision, as at the alarm panel, there are instructions in case of fire to disarm via the keypad and then open/close the panel door, which has another sensor attached. I assume this is how the power is 'reset' after an alarm.

what i assume is the first smoke in the series is where i am confused.

two sets of 4 wires, but they are not attached as I would expect or as the other smokes with the two wire sets are.

here is a pic of the wires: https://imgur.com/a/l4y12

it looks like there was one red wire which was unused and just looped back around the conduit. two black wires, two green wires and the white wires are spliced together with two little green wires coming off of it.

Like an idiot I did not take a photo of how the smoke was wired before unwiring it. I remember there were multiple wires in some terminals, with some unused.

I could always just wire it as it should be by the book, reds +, blacks -, greens together and whites together, but i have a feeling that the lack of a loop back from the EOL is the reason that one of these reds is unused and the whites are spliced together?

help!
 
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Old 01-24-18, 08:23 PM
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There should be a supervision relay at the end. It's job is to open the EOL and signal the panel with a fault if the 12vdc power gets lost. Depending on who did the wiring... it would not be uncommon for the relay to not be there.

Pretty hard to comment on the wiring methods used there and those splices.
The system wiring is very basic. 12vdc + & - and the two wires for the zone.
 
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Old 01-25-18, 04:47 PM
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There was one of the versions of the ESL 400 series that had a built in power supervision relay, but I suspect that what you have is the fairly common scenario of the eol relay failing, and someone chucking it and just dropping the resistor onto the terminals, assuming it was ever installed to begin with.
 
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Old 01-26-18, 07:24 AM
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thanks for your replies

so 2 of the smokes were wired as per instructions, 8 wires total (2 red/2 black/2 green/2 white). those i replaced fairly easily.

one smoke had only 4 wires, 1 red/black/green/white, with a resistor on the terminals between green/white. i replaced that with just 1 wire to each terminal and the resistor across the alarm terminals as it was before. there is no resistor across the power terminals.

the one I am at a loss on is in the basement, which i would assume is the first in the chain. the picture is in my original post.

it would seem like one of the red wires was not being used as it was originally wired.

in my two attempts at wiring it, i have had it trip the alarm and also give a trouble signal-- wouldnt that imply there was power supervision?

from what i remember (really kicking myself in the ass for not labeling or snapping a photo before unwiring it), there was a red and black wire in the same terminal and i think a black and green in the same terminal

any guesses as to how this could have been wired? as i mentioned there are instructions from the prior owner on how to reset the fire alarm involving disarming by keypad and then opening/closing the panel's door, where a sensor is attached to the door.

i really really appreciate your help!

Thanks
 
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Old 01-26-18, 04:24 PM
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Is it possible that the smoke you removed was actually a 2 wire model? I don't think it's likely.

There is a way to wire these using only 3 wires. Remember, the zone common, and aux power - are normally common on most common alarm controls, so it's possible that one of the cables has a bad wire, and they are using a single common and splitting it out to catch the alarm terminals as well as power negative. The remaining wires leave you with power incoming on one cable, power outgoing on the other cable, and zone in and out. A little checking with a multi meter would fairly quickly determine which.

One cable will have power, the other won't; but the one without power, you should be able to see your end of line resistance on common and one of the remaining wires.

A photo of the original would helped you out a lot. What was likely done here was once a fairly common hack.
 
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Old 01-26-18, 09:41 PM
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its definitely an ESL 449ct, although the wiring was not 'normal' since there were some terminals with more than 1 wire and some unused --which i dont really understand to be honest.

using the multimeter helped, i found that the grey conduit's green wire was 12v +

so far i have this:

grey (i assume goes to the panel)
green - +
white - spliced together to white from other conduit (common ground?)
red - unused
black - alarm circuit?

white (i assume goes to the next smoke)
red - +
black -
green alarm
white - spliced together to white from other conduit

i hooked up the smokes with the green wire from the grey conduit to +, and the red from the white to +
one of the common ground splice offs to - with the white conduit black wire (ground to next smoke) to the -

all the smokes power on now with the LEDs flashing, but i am still getting a smoke trouble alarm

im just not sure what to hook up to the alarm terminals.

the white wires seem to be ground, the green to the next smoke and the white splice offs show as in continuity with the multimeter

i feel like im close.

thanks
 
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Old 01-27-18, 03:31 AM
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What you are missing is continuity to the end of line resistor.

My best guess is that the black from the grey cable goes with the green from the white cable under one alarm terminal, and the common remaining common split off goes under the other alarm terminal. If they did what I'm guessing, that should restore your continuity to the EOL. and let you clear the zone trouble.
 
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Old 01-28-18, 07:45 AM
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no luck... still getting a trouble alarm with all the smokes powered. tried the black and green on one alarm terminal and the black with the green spliced off the white on the other terminal...

for some reason i remember having a red and black wire together on one terminal on the old smoke... wouldnt make sense to me given the red is definitely the + to the next smoke, but could it be some hack to reset the smokes?

i tried the black and red both on the second + terminal and powered up, the alarm went off with a fire signal.
 
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Old 01-28-18, 10:41 AM
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You have a confusing mess of wiring that you need to understand.

We open the connections and use a toner to follow the cables to their end. You can do the same with an ohmmeter. You need to get the cable from the panel to the first smoke wired so that you have red and black for power and white and green for the alarm point. Then do the same to the next smoke.

Without a standardized coloring method..... it's just guessing,.
 
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Old 01-28-18, 08:51 PM
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i agree... ill try that next.

before even starting this, a question i would have is how would the wiring differ if you were to wire these 4 smokes in a chain rather than a loop? i know thats how these are wired since the last smoke only had 1 set of wires and the resistor across the alarm terminals.
 
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Old 01-28-18, 09:30 PM
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Chain.....loop.... basically the same difference. The wiring starts at the panel, loops from detector to detector and ends at the last one. So the first three will have 2) four wire cables and the last will only have one cable. The EOL resistor goes across the zone point at the last detector.
 
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Old 01-30-18, 07:05 PM
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i followed your advice and traced everything back from the first smoke to the panel.

at the panel, there is a magnetic surface contact (which i assume acts to reset the smokes by opening/closing the panel after the smokes trigger). Wired red and black. Red goes to the panels 4 terminal. Black goes to a wire crimped to another black wire, which is part of the same 4 wire set that goes to the 1st smoke. Green and white wires go into a 4219 zone expander (Smoke is on Zone 12), red is unused.

after tracing it back it struck me that I was replacing these detectors, which I could never test b/c I didnt have 'canned smoke'. Why was I assuming they were wired correctly at the panel before?

I traced it again, thought a little and the red wire should not be on terminal 4 (ground), but on terminal 5 (aux +). Switched that guy over.

at the smoke, the black wire is (dc +) when the panel door is closed. green is the dc + from the zone, not the power for the smokes! white is the common ground, and red is unused, but could have just been ground if they attached ground at the panel end. hell they should have just crimped the black return from the mag sensor to the red of the 4 wire and grounded the black and the wires would have been sensical.

red/black/green/white to the next smoke are as they should be.

i am now realizing that the old 449CT and 445CT's didnt have a power LED, just an alarm LED. I could never trip the sensors to test that LED. They've likely never been on, presumably for the last 15ish years this system has been installed. Now i can truely understand the value of the EOL relay. If one had been used, this would have troubled from the start.

So now I have powered smokes that will alarm!

Thank you to you both, I wasnt really comfortable with the panel wiring but your encouragement pushed me to nose around and figure it out.

what I didnt know that would have helped me figure this out faster was the alarm loop also carries 12v + (makes sense in retrospect)

now to add the EOL relay...

I assume i just add this

https://www.systemsensor.com/en-us/Pages/EOLR-1.aspx

at the last smoke, such the red is to +, black to - and the violets are across the alarm terminals? if the system loses power it will latch and set the zone to trouble?

Thanks a BUNCH!!!
 

Last edited by SmittyMD; 01-30-18 at 08:16 PM.
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Old 01-30-18, 07:41 PM
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Not really, at most it's the same 1-2 volts that is used to supervise the loop.
 
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Old 01-30-18, 09:26 PM
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hmm.. i have a cheap multimeter, lights at 6 and 12... maybe its less and just fooling me.

but this site makes me think it could be closer to 12?

https://www.alarmgrid.com/faq/what-d...vista-p-system

there is no resistor at the panel or first smoke, just at that very last smoke, so wouldnt it all read close to 12?

either way, smokes powered up and pushing the test button triggers the panel and the onboard sounder, so I feel good about it.
 
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Old 01-31-18, 03:21 AM
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The smokes are supplied with 12v power from the smoke power source. The alarm loop supervision voltage is going to be less than 5 volts on most systems.
 
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Old 01-31-18, 08:57 PM
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Just to add my two cents worth. If you put those two purple wires directly across the zone point.... when power is lost... the fire alarm will be tripped. You need the EOL resistor in one of the purple wires.

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Old 02-04-18, 09:59 PM
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i see what your saying pete, i tried it with purples across the alarm terms with green on one and white on the other with the resistor across both terminals and the fire alarm signaled immediately after powering back on...

so should it be the green and purple to one terminal and the other purple with the resistor wired to the white on the other alarm terminal?

whats the best way to attach the resistor to the wires?
 
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Old 02-05-18, 03:28 AM
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No, the resistor goes _across_ the alarm terminals on the last device, otherwise, being a normally open circuit, the system never sees the resistor, and stays in trouble.

If you have an end of line _relay_, the resistor goes in _series_ with one relay leg, and that is connected across the alarm terminal on the last device.
 
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Old 02-05-18, 07:10 PM
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sorry now i am confused.

one alarm terminal have green and violet wires

the other would have violet and a leg of the resistor, other leg would be attached to the white wire?
 
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Old 02-05-18, 08:31 PM
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See if this helps a little better.

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