CPC used as interconnect on smoke detectors

[S P]

We all know this is wrong and breaches regulations and manufacturers instructions.

Good tread on this:
https://talk.electriciansforums.co....link-on-smoke-alarm-circuitwhat-would-you-do/

However the question is does it warrant a C2 over C3?
My recommendation is going to be radio link and reinstate CPC or rewire with 3-core. But what code to give?

GN4 recommends a lighting circuit supplying only class 2 as C3

 

[Octopus]

if you give it a C3, then the customer gets a satisfactory report ........ and who's to say they will do anything.

Whether you can justify a C2 is somewhat debatable, except all fixed mains cables should have a CPC in them which is functional - so a C2 imho

EDIT: I think the GN4 advice alludes to lighting circuits without CPC's and your installation has clearly been done incorrectly so the C3 is not really an option.

 

[Midwest]

Its just so wrong. How about that for a code.

 

[buzzlightyear]

I would code it c2 considering using the earth for the three core .

 

[telectrix]

debatable here. if the cpc is used as the interlink, then it's not carrying 240V. not right, but a C2 might be a little harsh.

 

[buzzlightyear]

debatable here. if the cpc is used as the interlink, then it's not carrying 240V. not right, but a C2 might be a little harsh

bit harsh ,why not, what if you hit them with a stick then!

 

[S P]

Thanks guys, have to send it off tonight so going with C2 under points 5.8 + 5.9 of the inspection schedule

 

[pirate]

as a non-electrician, I have a question...
if the cable used to interconnect is at mains voltage, shouldn't it have a cpc, even if the individual detectors don't need one?

If the detectors were non mains supplied, then any 3 core cable would do the job, but T&E presence might cause unnecessary confusion to someone opening up at a later date?

Radio interconnect is an option (a good one, imho) but not an option in rented housing...but in Scotland it will be soon, thankfully.

Hope i have explained that correctly...

 

[S P]

There is a DIY fitted duel RCD board with all the circuits on one RCD and the second empty!!! Except for 2 lighting circuit non RCD protected.
Idiots!
I've got it down as C3.. Sup bond in place

 

[buzzlightyear]

Thanks guys, have to send it off tonight so going with C2 under points 5.8 + 5.9 of the inspection schedule

is it nice to get it off your chest.

 

[S P]

It's not a separate cable the've used Pirate, it's T+E with the CPC over sleeved live and used as interconnect. Hence the problem, no CPC and no basic insulation for interconnection

 

[Midwest]

Well every point on a low voltage circuit has to be provided with a cpc (reg?). So that's that surely code whats is face.

 

[westward10]

A few years ago I did a periodic at a charity shop which had Part 6 detection. The shop was in darkness when I showed up because the manager was waiting for me to turn up to show me a trick. As she switched on the shop area modular fluorescents the detectors triggered. Turns out the interconnection was the cpcs which were also connected at some point to earth.

 

[Nigel]

Interesting one here.

My initial reaction is a C2. Then when you think about it it is 8-12 volts DC that only has a single layer of insulation.

Would I C2 a speaker cable in the wall? No of course not.

If everything is also Class 2 then again I fail to see how to code this.

 

[sparkdog]

Don't think its really a potential danger per-above post.

 

[sparkdog]

Don't think its really a potential danger per-above post.

 

[Lucien Nunes]

My initial reaction is a C2. Then when you think about it it is 8-12 volts DC that only has a single layer of insulation.

But 12V with respect to what? A live conductor. If you connect one side of a PP3 to mains, the PP3 is still 9V but now it's potentially lethal (pun intended).

 

[Wilko]

as a non-electrician, I have a question...
if the cable used to interconnect is at mains voltage, shouldn't it have a cpc, even if the individual detectors don't need one?

If the detectors were non mains supplied, then any 3 core cable would do the job, but T&E presence might cause unnecessary confusion to someone opening up at a later date?

Radio interconnect is an option (a good one, imho) but not an option in rented housing...but in Scotland it will be soon, thankfully.

Hope i have explained that correctly...

Yes all cable installed shall have suitable cpc travelling with it. I'm not aware of battery alarms that ask for wire interconnect, so not thought about that one. It does annoy me that some folks steal it for some other purpose. Radio clearly the way forward for difficult situations .

 

[Pete999]

The cpc in this case, has a distinct possibilty of making contact with one of the Live conductors in the detector and or the cable itself, if the cable become damaged, the cable is not being used as it should, so it should be replaced with a cable that is fit for purpose.
It's an inherently dangerous thing to do in my bok, would you use the cpc in respect of the strappers in a 2 way lighting circuit, well I know I wouldn't with that in mind you should code it as dangerous.

 

[Risteard]

Then when you think about it it is 8-12 volts DC that only has a single layer of insulation.

The cpc core is uninsulated.