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Discuss Smoke detectors + 17th edition in the Electrical Forum area at ElectriciansForums.net

S

stevie h

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Doing a rewire at the mo , its my 1st one under the new regs , going to use a 17th edition double split RCD board , are the mains smokes ok to go on one side of the board ? or do they need to go on there own RCBO

Cheers

Ste
 
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E

EasyFox

  • Thread Starter Thread Starter
  • #2
Idealy need to be on their own rcbo.
 
G

greekislandlover

  • Thread Starter Thread Starter
  • #5
Well, what we were tought at college is that smokes can either be connected to their own circuit , or run off the lighting circuit - preference being lighting.

Reason being that if the smoke alarms sound, then the occupants can flip off the breaker. And the problem is that when they do flip off the breaker with the intention of getting it fixed they never do. Therefore, if the smokes are connected to the lighting circuit and a fault develops they can't just switch off the breaker without losing the lights - they have to get it fixed.

So I'd personally still wire them to the lighting circuit.
 
T

tony.towa

  • Thread Starter Thread Starter
  • #6
If you are wiring of a lighting circuit remember to rum the live and neutral from the same circuit. The majority of detectors on the market have the third wire connection link which is basically a switched live which closes when a detector operates. If the detectors are not fed with the live and neutral from the same lighting circuit when they operate one of them will have a "borrowed neutral" which will trip the rcd and hence no alarm operation. If possible use the downstairs lighting circuit then you will also be providing the downstairs neutral to the area of the landing light.
 
P

PAUL M

  • Thread Starter Thread Starter
  • #7
dont forget you are not supposed to put smokes on the same rcd as socket outlets,i know its a crock but its in the regs.
 
S

stevie h

  • Thread Starter Thread Starter
  • #8
dont forget you are not supposed to put smokes on the same rcd as socket outlets,i know its a crock but its in the regs.

Thanks Paul , this is the reason i started the thread , i remember seeing this somewhere (professional electrician mag maybe)so if i put in a 17th edition board with the up skts on one side and down on the other, i cant fit the smokes on it ??..... unless i use an mk board which has 2 rcd,s and space for RCBO,S

Cheers

Ste
 
P

PAUL M

  • Thread Starter Thread Starter
  • #9
you need to fit what they call a high integrity board,or in normal language a board which as a couple of unprotected ways for your rcbo,crabtree do one but its quite big ,depends how much space you got i suppose.
 
A

ash2020

  • Thread Starter Thread Starter
  • #10
To my mind, the most suitable option is definitely to run the smokes off a lighting circuit, preferably downstairs. There's too much temptation to sometimes leave them switched off if they're separate.
When battery only ones were used, which one of us didn't disconnect the battery sometimes? (When my Fluke battery went flat it was the obvious place to find a 9V PP3!)
Why would you want to use an RCBO if you didn't have to?

Cheers
Andrew

BTW. I definitely don't feel like a junior member. Coming up to 60, all my hand joints ache after a day on the tools and don't get me started on the state of my knees!

Still, I've now got myself some very nice trousers from Screwfix which have knee pockets for soft knee pads. New lease of life!

Andrew
 
Last edited by a moderator:
S

stevie h

  • Thread Starter Thread Starter
  • #11
You arnt allowed to put your smokes on the same rcd as your sockets , so on a new 17th edition board you have up skts and up lights on one RCD protected side and down skts and lights on the other .... now as smokes cant be on the same side as the RCD protected skts were do they go ?

RCBO i assume ? and i take it that is the reason that lots of 17th edition boards come with 1 x 5amp RCBO

Well that's how i see it now after some advice off you guys :)

Ste
 
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D

DYCHE4230

  • Thread Starter Thread Starter
  • #12
Well, what we were tought at college is that smokes can either be connected to their own circuit , or run off the lighting circuit - preference being lighting.

Reason being that if the smoke alarms sound, then the occupants can flip off the breaker. And the problem is that when they do flip off the breaker with the intention of getting it fixed they never do. Therefore, if the smokes are connected to the lighting circuit and a fault develops they can't just switch off the breaker without losing the lights - they have to get it fixed.

So I'd personally still wire them to the lighting circuit.
Don't the Smokes still have to have there own form of isolation separate to the lighting circuit??? So they could just isolate the smokes anyway...Just a thought...

Looked thru the OSG last night could n't see anything about the smokes not allowed on the same circuit as sockets does it say this in the main Regs, if it does they should put it in the osg too don't you think or did I completely misread the OSG. (It was late)
 
A

Andy M

  • Thread Starter Thread Starter
  • #13
The new on site guide says "where all circuits are protected by rcd's there is advantage in supplying detectors and alarms from regularly used lighting circuits" page 66

so on one of these twin rcd boards (which personally i don't think comply, circuits should be divided....blah ..blahh to avoid inconvenience etc but customers don't really want to buy all rcbo's! ) you could put power and one lighting on one rcd and the circuits which traditionally (under the 16th) went on the main switch with the lighting circuit incorporating the smokes on the other.

two more points-

page 65 on site guide says " be permantly supplied from an independant circuit from the dist board or supplied from local regularly used lighting circuit(there shold be a means of isolating the suplly to the alarms without affecting the lighting).

what is this all about, blows the theory about the customer not turning turning off the smokes, it will be like fan isolators, which are intended for mechanical maintenance but are used so the fan doesn't wake up the house at night!

point 2 Why shouldn't the smokes be on the same rcd as the sockets ? what reg is this ? what difference does it make, whether the smokes share an rcd with sockets or cooker or lighting circuits for that matter?

i consider myself reasonably intelligent, despite only getting 57 out of 60 in my 17th regs exam the other day ( maybe i should have attended the course and paid £500 rather than self study!) sorry couldn't help a bit of showing off. But as per usual the regs are as clear as mud and i am confused.com!!!!!!!!!!!!!!!!!!


Oh **** it i am going to bed!
 
D

DYCHE4230

  • Thread Starter Thread Starter
  • #14
The new on site guide says "where all circuits are protected by rcd's there is advantage in supplying detectors and alarms from regularly used lighting circuits" page 66

so on one of these twin rcd boards (which personally i don't think comply, circuits should be divided....blah ..blahh to avoid inconvenience etc but customers don't really want to buy all rcbo's! ) you could put power and one lighting on one rcd and the circuits which traditionally (under the 16th) went on the main switch with the lighting circuit incorporating the smokes on the other.

two more points-

page 65 on site guide says " be permantly supplied from an independant circuit from the dist board or supplied from local regularly used lighting circuit(there shold be a means of isolating the suplly to the alarms without affecting the lighting).

what is this all about, blows the theory about the customer not turning turning off the smokes, it will be like fan isolators, which are intended for mechanical maintenance but are used so the fan doesn't wake up the house at night!

point 2 Why shouldn't the smokes be on the same rcd as the sockets ? what reg is this ? what difference does it make, whether the smokes share an rcd with sockets or cooker or lighting circuits for that matter?

i consider myself reasonably intelligent, despite only getting 57 out of 60 in my 17th regs exam the other day ( maybe i should have attended the course and paid £500 rather than self study!) sorry couldn't help a bit of showing off. But as per usual the regs are as clear as mud and i am confused.com!!!!!!!!!!!!!!!!!!


Oh **** it i am going to bed!

Exactly!!
 
  • Thread Starter Thread Starter
  • #15
Page 17 Professional Electrician october issue. There's an article on this.

Basically it says recently published advice from NICEIC, ECA and SELECT recommends not to use a dedicated circuit.

"If smoke alarms are on a dedicated circuit there is a distinct possibility that the user will accidently or on purpose turn the circuit off"


Mark
 
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