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.