Single light on radial - inline switch?

[alanl]

I'm wiring up my garage.
As there will be only one light fitting on the 6A radial, is there any reason why I couldn't put the switch inline, between the MCB and fitting, rather than the more typical cable to fitting, then a switched live going to the switch from the fitting?

I can't see why not, but would like the opinion of more experienced people.

Thanks
Alan.

 

[malcolmsanford]

As you can use the MCB as your switch why not just do that and save any kind of switching. I'm assuming you have a the MCB local in ther garage.

 

[malcolmsanford]

I initially made a mistake in part a) which I corrected. I believe your book does not account for the translational energy of the extended cord. If I use only the 18.62 J of rotational energy divided by time, I will get 100.7 J. Also it is not clear whether the mass of 100 g includes the extended cord or not. This may account for the discrepancy between my answer and the book's.

hmmmmmmmmmmmmm there's me thinking that a 1 gang would have been ok

 

[alanl]

As you can use the MCB as your switch why not just do that and save any kind of switching. I'm assuming you have a the MCB local in ther garage.

Yes, 3 way DB fed by SWA from the CU in the house. Only 2 outlets in the garage, a double 13A socket, and the light. No, the MCB won't be used for the switch, not easy enough to turn on (behind cover, and 6 foot high), and it is not designed, IMV, to be used as an on/off switch for an outlet.
Alan.

 

[Adam W]

Yeah fine, nothing wrong with that at all, just connect the neutral in the back of the switch so it's accessible.

 

[malcolmsanford]

So if you CU is 6' in the air and you want to wire direct from the MCB via an in line switch to your light which I assume is on the ceiling, where are you going to fit the switch?

 

[alanl]

So if you CU is 6' in the air and you want to wire direct from the MCB via an in line switch to your light which I assume is on the ceiling, where are you going to fit the switch?

Around 18" below the DB. Straight run down to the switch,and back up to the ceiling.

 

[Hawk81]

As you can use the MCB as your switch why not just do that and save any kind of switching. I'm assuming you have a the MCB local in ther garage.

I might be wrong and don't have the regs with me at the mo but I think that an mcb should not be used for functional switching.

 

[malcolmsanford]

Then what your describing is every switching arrangement in every house in the UK. An in line switch to me is a topedo switch similiar to what you would have in a flexible cord of a lamp.

Instead of a loop in out system at a celing rose. your just doing a loop at the switch system, where you normally have the line/neutral at the switch and the S/L neutral at the light

 

[malcolmsanford]

I might be wrong and don't have the regs with me at the mo but I think that an mcb should not be used for functional switching.

Table 53.2 a BS 60898 Circuit breaker can be used for isolation, emergency and functional switching.

 

[Hawk81]

Table 53.2 a BS 60898 Circuit breaker can be used for isolation, emergency and functional switching.

Ok I was wrong

 

[malcolmsanford]

I know I expect your like me it does not sit right switching off a lighting circuit from the DB, but a lot of retail shops do this as it saves money on running switch lines and lives back down to switches.

An older engineer told me that in fact the switching mechanism of an MCB is far superior to that of a normal switch, and I never had reason to doubt him as he was normally right.

 

[Hawk81]

Yeah he probably is right. I just don't like the thought of people have to constantly go to a DB to turn lights on and off.

 

[malcolmsanford]

Totally agree with you in that. or you throw the wrong MCB it is fraught with many problems, but is is still done in many places.

 

[telectrix]

just visualizing one of those open blade double pole switches on the wall like in frankenstein's lab, loads of sparks and the monster twitches. LOL.