Landing light on a Re-wire..

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Feb 12, 2008
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Hello chaps,

I have been thinking...

When you do a rewire (16th Ed) Do you think it waould be a good idea to put a landing light and the Smokes on the same MCB? I know that it is recommended to have the smokes on their own dedicated radial, but it's just a thought.

So that would be upstairs Radial, Downsatirs Radial and a smokes & Landing light Radial.

What do you think?

Nay or Yay?



Feb 14, 2008
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Ive read something before cant remember where about this it recomends putting smokes on with landing light so when ur ****ed u cant tamper with the smoke if it goes off when your burning the kitchen down with ya chip pan because you cant see.

It makes sense if you cant see then your less likely to tamper.

Regards darron

Mar 7, 2008
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In the office again.
Afternoon Wizzer.....

I`d have to say nay - don`t actually see any point in it ? (sorry)

Landing light would be on up radial, which is likely to be in the vicinity anyway.

Anyway, T+E to 1st smokey, then 3+E to rest (as per BS5389-6) - easier to take twin to hallway or lounge smokey (dependant on layout obviously)

I may be wrong on this final point, as I haven`t checked yet, but my belief is that the smokeys should be on a dedicated mcb - BS5389-6 again (IMHO).



Mr Sworld

Electrical Technician
Mar 21, 2008
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Yes, I have thought about lights on a smoke alarm circuit. There is a school of thought that if the smoke circuit trips out then a houseowner may not realise it or care! However if one or two lights go out as well they will realise it and do something about it. :eek:



Well-known member
Mar 24, 2008
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Yeah i agree with you with leaving a landing light on for identifying your escape route and to aid you if it does trip like the above point says.

But i do agree with it being on its seperate circuit as it should be.

A bit of tricky one this. ?:|

Is there no where that sells smokes with a light fitting on it and it comes on when no mains power or activation.


biker mike

Senior Member
Feb 15, 2008
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Yes, I have thought about lights on a smoke alarm circuit. There is a school of thought that if the smoke circuit trips out then a houseowner may not realise it or care! However if one or two lights go out as well they will realise it and do something about it. :eek:
I agree Mr S ,people are lazy how many houses have you been to where the 9v battery has gone flat in the smoke sensor,or not one there at all , so if its on the lighting circuit ,you know that it will be on all as long as the circuit hasn't tripped and if the lights dont work they'll take positive action to turn them back on again ,whereas if they are on a seperate circuit unless they test them everyday manually by pressing the test button then they wont know if they are working.

I know some come with led's but honestly how many people look to see if they're on ?? personally i'd connect to lighting circuit ...


Mar 28, 2008
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Evenin chaps'

wherever possible I always wire smokes onto thier own dedicated circuit.

[ I have only once put them onto a lighting circuit when it was nigh on impossible to get a cable run down the the fuse box without wreking the decoration and the customer didn't want to pay a lot. ]

Here's my reasons.....

first the bedtime reading bit: You 'can' do either...

reg 563-01-01 pg 131 16th ed, and reg 560.7.1 pg 153 17th ed

refer to circuits suppling saftey services, (which include fire detection),

stating they should be on thier own dedicated circuit.

On-Site-Guide 7.4.1 Pg 56 says smoke alarms in single dwelling can be wired as above OR from a local regularly used lighting circuit.

Whichever method you chose...

you need a means to isolate the smoke alarms for maintenace work.

i.e. when you change the battery on a lot of alarms you need to unplug the mains connector to open the battery compartment.

(not good for customer to do this on a live circuit!)

where are you going to put your isolator switch?

probably need a fused spur off light circuit because

not much good turning off lights MCB as you may not be able to see what you are doing?

What is the real risk of a dedicated smoke circuit tripping itself off?

As you are not putting any extra load on or switching stuff on or off..

why would the smoke circuit trip out??

unless you manually isolate it I guess it will just stay on!

Whereas a lighting circuit is more probable to trip cuz a bulbs blows!!

There is more probability that you would have the light circuit turned off for repairs/alterations/additions...

whilst you do this your smoke alarms are not powered!!

There is a greater risk that DIY bob changes a light fitting and may leave a wire off/lose/reversed...

jeapardising the continual supply to the smokes.

How can you easily check the supply is on to the smokes?

I put a FCU with neon indicator next to the CU!

smokes from MCB through FCU (only need 3A anyway not 6A protection)

Then supply to downstairs then to upstairs (and on to loft if applicable).

Quick glance at the neon on the FCU you know the smokes have power.

Also FCU provides nice easy Double Pole isolation for customer (or spark) to use when changing batteries!

When you are teaching customers about the MCBs & RCD operation.. you just tell them to keep an eye on smokes.

any person who is genuinley concerned about the saftey of thier family will check it and keep an eye on it & change batteries...

Customer who dont care wont give a fig or do anything no matter what circuit you wire it from!! :|

Well thats my four penny worth! :D :D

me fingers are worn down:( & now Im going to have a cup of tea... :D :)