Accenta G4 - 1 Wire Zone Possible?

[NickH]

I would like to add an additional zone to an existing install. 

 

Sadly, although the cable i have access to is 8 core, some clown has cut/failed to connect one of the cores further up the line, so instead of a spare pair, i have a spare single!

 

I was wondering if it is possible to share a common return for a zone to add an extra door contact.

Without going into full detail, lets assume (ignore tamper and power) i have a PIR zone on yellow & blue, and a spare orange wire.

 

I was thinking about linking out the first pin on zone 1 (blue) with the first pin on zone 8 at the board.

The second pin for Z1 (yellow)

The second pin for Z8 (orange)

 

The PIR is then wired on z1 across Blue/Yellow

The new door contact on Z8 across Blue/Orange

 

This seems like it would work assuming the microprocessor regards each input as either a isolated switch, or shares a common +ve or -ve for each zone (actual system schematic would help) In the latter case it would be essential to know which of the zone pins is shared.

 

Has anyone ever tried this before?

 

Nick

 

[james.wilson]

I have on bigger panels. In theory it should work using the output of the circuit for 2 inputs

[al-yeti]

1 hour ago, james.wilson said:

I have on bigger panels. In theory it should work using the output of the circuit for 2 inputs

On a G4?

[PeterJames]

Ive done it before you need to see which circuit terminals are common, I havent tried with an Accenta. But that said I would think the person who ran the cable would be more of a clown if he joined one of the unused wires and not the other, my money would be on a damaged cable rather than a clown installer. 

 

Is  EOL not available or is the panel too early?

[al-yeti]

2 hours ago, PeterJames said:

Ive done it before you need to see which circuit terminals are common, I havent tried with an Accenta. But that said I would think the person who ran the cable would be more of a clown if he joined one of the unused wires and not the other, my money would be on a damaged cable rather than a clown installer. 

 

Is  EOL not available or is the panel too early?

Op installer ......

[NickH]

The original install was a 2 Zone Bently system installed 30+ years (cabled during construction). Over time all the panel LEDs have blown, and recently during some decoration work tradesmen removed the PA causing the panel to go into alarm. At this stage, we realised that the bell was no longer working. Some testing later and there is no supply for the bell from the Mosfet. Hence a new panel.

 

The old install had a PIR and door in series for INT and TA, but on an 8 core cable so it seemed an obvious choice to use the spare pair for the second zone, except as above shorting the pair at the far end gave no continuity. (but i can prove the orange is good by shorting to the TA pair)

 

I don't understand the reason why (perhaps you guys might know?) but for this circuit they ran an 8 core from the panel but only a 6 core comes out of the coving to the PIR, with a junction behind the coving. The 8 core then continues behind the coving round the room before popping into a small loft where the 8 core is junctioned onto 6 core for the door. The black and red is disconnected onwards from the PIR which makes sense, as there was no need to run power to the door. Why would they have used 8 core - maybe they had loads on the van, but i cant see any other reason to have done so? 

 

I'm a comms guy, so I have tone tracers and a TDR meter which shows that the "break" is about 20cm closer to the panel than the pair used for the PIR power - My guess is therefore that the break is at that first junction which is not accessible

 

The G4 zones don't seem to have common pins - there are a few kohms between the first pin on each zone, and more between the second pins, so i'm guessing all go back to the micro rather than a simple pullup/pulldown arrangement.

 

 

[sixwheeledbeast]

Replacing a 2 Zone Bentley (ok in it's day) for a relatively budget G4 panel seems a bit of a downgrade. Decent panels would have give you EOL options.

Years ago cable was relatively expensive so you often had situations where only the cable with cores required was used in each run. 6core to a PIR then 4core from there to a door and the like.

Could also be what they had in the van to get it working, or some dodgy repair, who knows.

Really it just needs those zones re-cabling instead of messing IMO,

[al-yeti]

2 hours ago, NickH said:

The original install was a 2 Zone Bently system installed 30+ years (cabled during construction). Over time all the panel LEDs have blown, and recently during some decoration work tradesmen removed the PA causing the panel to go into alarm. At this stage, we realised that the bell was no longer working. Some testing later and there is no supply for the bell from the Mosfet. Hence a new panel.

 

The old install had a PIR and door in series for INT and TA, but on an 8 core cable so it seemed an obvious choice to use the spare pair for the second zone, except as above shorting the pair at the far end gave no continuity. (but i can prove the orange is good by shorting to the TA pair)

 

I don't understand the reason why (perhaps you guys might know?) but for this circuit they ran an 8 core from the panel but only a 6 core comes out of the coving to the PIR, with a junction behind the coving. The 8 core then continues behind the coving round the room before popping into a small loft where the 8 core is junctioned onto 6 core for the door. The black and red is disconnected onwards from the PIR which makes sense, as there was no need to run power to the door. Why would they have used 8 core - maybe they had loads on the van, but i cant see any other reason to have done so? 

 

I'm a comms guy, so I have tone tracers and a TDR meter which shows that the "break" is about 20cm closer to the panel than the pair used for the PIR power - My guess is therefore that the break is at that first junction which is not accessible

 

The G4 zones don't seem to have common pins - there are a few kohms between the first pin on each zone, and more between the second pins, so i'm guessing all go back to the micro rather than a simple pullup/pulldown arrangement.

 

 

Dude get rid of it and buy a hybrid panel and your done really 

[MrHappy]

3 hours ago, NickH said:

The original install was a 2 Zone Bently system installed 30+ years (cabled during construction). Over time all the panel LEDs have blown,

 

Really ?

 

What other 30yr old constantly on electronic kit in your house have you still got ?

 

3 hours ago, NickH said:

I don't understand the reason why (perhaps you guys might know?) but for this circuit they ran an 8 core from the panel but only a 6 core comes out of the coving to the PIR, with a junction behind the coving.

 

 

The sensors been dropped when the coving was added...

 

3 hours ago, NickH said:

Why would they have used 8 core -

 

 

Many people only buy 8 core.... saves having lots of different reels & wiring in 6 when 7 pairs are needed....

 

3 hours ago, NickH said:

I'm a comms guy,

 

 

you have my my deepest sympathy...

 

3 hours ago, NickH said:

I'm a comms guy, so I have tone tracers and a TDR meter which ....

 

You need nothing better than a DVM - Voltage, Current, Resistance. voilà every measurement need for an alarm circuit

 

3 hours ago, NickH said:

The G4 zones don't seem to have common pins - there are a few kohms between the first pin on each zone, and more between the second pins, so i'm guessing all go back to the micro rather than a simple pullup/pulldown arrangement.

 

 

Throw it away & buy something less shite,

 

If I wanted to bodge your knacked old alarm to together-

 

Adjust stetsons to correct angle, check for indians (not you Al  )

 

Assume tamper is a negtive loop,

 

Assume 12hr circuits are positive loops 

 

At the controls place + voltage into one leg of an unused unlinked zone, if not closed try the other leg

 

Should it not work or the controls start smoking see underlined text or try - ?

[Hillbilly]

Bin everything and go wireless!