Problem of the week

[Doc Hudson]

Has anybody asked themselves WHAT voltage is usually applied to the interlink wire in the smokies?

As most mains powered, battery back-up, interlinked smoked detectors, still work interlinked whilst running off the batteries. Any signal down the interlink wire is unlikely to be greater than the back-up battery voltage. Typically this could be a 9v DC alkaline battery. The interlink would not be 230v AC as it would not work when the mains fails.

Doc H.

 

[ProDave]

...part of the reason why BS5839 forbids the use of the brown wire for the interlink (see quote below)...."Clause 16.5 © of BS 5839-6: 2004 states, with regard to the wiring of Grade D and E systems, that ‘conductors used for interconnection of smoke/heat alarms should be readily distinguishable from those supplying power (e.g. by colour coding)’.

... should be identifiable not by the colour brown (which is used for the phase conductor of the 230 V a.c. power supply), but by some other colour appropriate to a phase conductor, which must be in accordance with the requirements of BS 7671.

Has anyone else seen certain makes of smoke alarms that nicely colour code the terminals for you?

L in is brown. N is blue, and the interlink is GREY.

So your 3 core & E interlinking cable goes brown to L, Grey to inter link, and erm,well that only leaves BLACK for the neutral. Oh dear, that means by following the manufacturers instructions as close as I can, I have comitted that cardinal sin, of using a BLACK for neutral.

Sorry for the thread drift.

 

[Evans Electric]

OMG!!! He used Black as Neutral !!!!! What sort of people are on this Forum ???? How dare he use his own initiative ,OMG! the confusion of opening one of his smoke detectors and seeing a BLACK neutral , I mean what would one do when faced with such a diabolical disregard of the perceived method of forgetting that the black used to be neutral but now we use the grey and colour it BLUE and because the black will now be the interlink we colour that brown , I think !! :C

 

[ProDave]

I've thought for a VERY long time that we are short changed with the available colours of cables. The 3 core cables are all geared up to being 3 phase colours. But I'm willing to bet in 99% of cases they are used on single phase installs.

How much better it would be, if we had a 3 core cable available to us coloured brown, blue and grey.

Back to the thread topic. When is Steps going to publish the answer?

And if nobody else has a question, I have one for next weeks "question of the week" Should I start that as a new thread once this weeks answer has been posted?

 

[Evans Electric]

Best to wind this one up first ....COME ON STEPS ...what was going on ? Dave has next weeks on the back burner.

 

[steptoe]

sorry guys, been crazy hours this week, as I said didnt get home til gone midnight last night, Im going to do a drawing as I think that will be easier,

I'll get it done as soon as I have had some food.

 

[donnie1986]

This same problem was highlighted on a t&i course I attended by the lecturer. To which everyone looked at him in confusion.

If a 3 core + e was used and the grey was not used as the common, capacitance can build up and cause cheap CFL lamps to strike, then go out, when the capacitance builds up it strikes again. This is fixed by using the grey as a common, which means the earth takes away any charge.

Does this sound like the problem you were facing?

 

[steptoe]

this , my friends, is as best as I can envisage the fault,

I actually sorted it by ripping out most of the connections, doing some continuity testing and reconnecting with less wires than were there when I started,

any ides as to what was occurring? I have my own thoughts, but I may be wrong.

nb: please dont be jealous of my artistic skills, a lifetime of learning with an inbuilt natural talent.

 

[Manator]

I will just rotate that for you Steptoe

 

[steptoe]

I did actually when it came off the press,

well I did it the way Deke told me to. :|

 

[Manator]

I can see the problem now a diagram has been posted, speaks far louder than the written word.

 

[springcrocus]

Steps, are you missing a pair of wires? How did they turn the hall light on?

 

[steptoe]

TBH its pretty much irrelevant. the only fact having a bearing was the landing light having its feed from the hall, and the fact the hall light when on was providing a feed, the actual switch doesnt have a bearing so I saw no need to include it.

you can put 2more terminals beside the downstairs landing light switch if you want.

 

[kme]

All I can say is, the loft light only matters insofar as it was the catalyst for the JB to be added...........and that looks like one mega balls-up

 

[ProDave]

The obvious mistake is the smoke alarm interlink appears to connect to the hall switched live.

So I take it the smokes are goosed as well?

 

[steptoe]

yep, the smokes were goosed, so just expensive JBs ! and a mess up of linking the wires through them, notice how they are fed from both lights!

 

[Evans Electric]

So, where do I collect my prize?

 

[Doc Hudson]

I have split the two subsequent problems off onto their own threads as this thread will become excessively long over time and it will be hard for new readers to locate the beginning of a problem. All problem threads have been moved to the Student area as this was the intention that Guy implied form his initial request, for experienced members to post problems to help student get their heads around problem not encountered in a college environment. Please Start new problems on a new thread.

Doc H.

 

[steptoe]

So, where do I collect my prize?

P155 off you old fart,

I told you it was for learners, oh, ok then, you can have any can of cheap cider from under the counter!