Full rewire

[amtodd]

Breezer, I'm just checking what I thought I'd learned properly is correct.

Can you please clarify whether mains powered smoke detectors (as opposed to intruder or proper fire alarms, where I know to fit an independant supply) may be wired from a lighting circuit. My understanding is it is preferred to run a seperate circuit, but that connecting - in a domestic premises where a fire alarm is not required (House in Multiple Occupation, certain multi story builings etc.) - smoke detectors to a lighting circuit is an alternative provided the circuit is labled as powering smoke detectors.

 

[breezer]

you can

 

[masona]

smoke / heat detectors wired to an intruder alarm are a pain in the elbow, you are led to belive you have a fire alarm,

I can't see how ? mine is link up to the alarm system and have no link-up to police or fire station etc.Maybe you're not talking about the one I've got?

 

[breezer]

i am, seen lots of them, people say something like "are you going to make any smoke as i have a fire alarm, and the alarm company will send the fire brigade if you set it off"

they say that when i get there but never the plumber who does make smoke.

you look for a fire alarm and can only see one smoke detector, few questions later, and you find out it is on the burglar alarm, I then expalin the difference

 

[masona]

"are you going to make any smoke as i have a fire alarm, and the alarm company will send the fire brigade if you set it off"

Ahhh you see,how will the alarm company know my fire alarm gone off ??They have no way of knowing as the same as the police and the fire station.My alarm is internal alarm for my family.

 

[breezer]

i did read your post, in that it is "bells only" but i was generalising regarding smoke detectors on intruder alarms

 

[Knightswood]

I should have said smoke alarm in a domestic cct.

That'll go on the Lighting cct since I don't have any spare circuits in the box and I'll mark it up as an Smoke Alarm & Lighting Bla....


Thanks for your help.

 

[eyeofthebeholder]

sorry to pull up an old topic, but it is quite relevant.

I am currently planning for a rewire (as you have probably guessed by now ). It says above that mains smoke/heat/CO2 alarms need to be run from their own CCT rather than from the lighting CCT.

My problem is that, as I have a town house, and wish to put an alarm in most of the the rooms (9 in total) across the three floors. This will probably exceed the 100m cable run for the one CCT. Based on the regs for fixed lighting cable length, 100m is the maximum run and therefore will have to install two CCTs just for the alarms.

Is this correct? Is there anyway round it?

Thanks

Ad.

 

[Adam_151]

Where have you got this 100m figure from?

Design the circuit properly and you can have any length you want

 

[eyeofthebeholder]

Looking in the 'Electricians Guide to the Building Reg'.

It shows a table with Maximum cable lengths for various final circuits. The specific heading is 'TN-C-S PME earth Ze up to 0.35Ohm'

Eg.
Cooker: 30m
Immersion Heater: 30m
Shower: 40m
Fixed Lighting: 100m*
*including switch drops.

Is this not what is it talking about and I am barking up the wrong tree?

Cheers

Ad.

 

[CallEdsFirst]

I had an ADT alarm which was linked to the smoke alarms. In theory if the smoke detectors were tripped and not reset within a few minutes (I think it was two minutes) the system dialed the control centre. The control centre then dialed me. If i was at home I could tell them the alarm was false, and they would reset, but if I was not at home, they would advise the Fire Service, who would go round and break the door down!

Fell out with ADT, so the present system is mains with duracell back-up.

By the time they'd smashed 8 doors in, I was pretty angry!

By the by, Eyeofthebholder, by the time you have got all the knowledge to complete the various projects you are asking about on here, you may as well do an apprenticeship, C&G, NVQ and part P 5 day wonder!

 

[Adam_151]

Do you have a TN-C-S supply for a start? no good using that table if you have a TNS supply with Ze of 0.5 is it?

Anyway, thats a catch-all chart of 'standard circuits' it seems to be an even more basic version than the OSG gives you

quick fag packet calculation indicates that its not the R1+R2 that seems to be biting,must be the volt drop, and with smoke alarms the design current is going to be tiny, so it shouldn't be a problem to design a compliant lengthy circuit without pushing up the world copper price , even if the circuit was for luminaires you could still do it, you'd just have to pick a suitable cable size

 

[eyeofthebeholder]

Cool - thanks for your help!

 

[eyeofthebeholder]

By the by, Eyeofthebholder, by the time you have got all the knowledge to complete the various projects you are asking about on here, you may as well do an apprenticeship, C&G, NVQ and part P 5 day wonder!

I have thought about this, but what would I do with it afterwards, as unless I keep up with doing electrical work I would loss my Part P would I not?
How much does it cost to do all the required exams and training off the top of your head?

Cheers

Ad.

 

[CallEdsFirst]

so it shouldn't be a problem to design a compliant lengthy circuit without pushing up the world copper price

Do it! More margin for me!!!! Mwahahahahahah