Contactor wiring to d/b

[c.boy]

Hi all,
Now every days a school day!!Not had many dealings with contactors!!!!!I know it's just basically a switch but better to ask I feel!!I have a new consumer unit to install for a 7 storey block of flats.The (sub)d/b is for the stairwell and the communal lighting. The lights are to be controlled with a photocell and contactor.The ? I have is can I take the live and neutral from the main d/b into the contactor first L1 and L2 then into the main switch in the new d/b, the photocell will be off another mcb and the switched live goes into A1?? For testing r1 r2 link the live through at the contactor??

 

[Leesparkykent]

Why do you want to take the distribution circuit for the new DB through the contactor ?

 

[davesparks]

If you need the whole DB controlled then you could just use a contactor incomer instead of a switch.

 

[ImpededLoop]

You can indeed switch the supply to the 2nd db using a contactor. The control circuit can be fed from another circuit breaker as you suggest. Control circuit line and neutral to A1 & A2 via the photocell.

Suggest you also install a switch in parallel with the photocell for testing/override purposes.

 

[c.boy]

Why do you want to take the distribution circuit for the new DB through the contactor ?

I was thinking that as the new d/b is controlling all the lights when the contactor kicks in then the d/b is energized.

 

[c.boy]

You can indeed switch the supply to the 2nd db using a contactor. The control circuit can be fed from another circuit breaker as you suggest. Control circuit line and neutral to A1 & A2 via the photocell.

Suggest you also install a switch in parallel with the photocell for testing/override purposes.

Yeah forgot to mention that in the post!! Thanks

 

[c.boy]

If you need the whole DB controlled then you could just use a contactor incomer instead of a switch.

I'm not supplying the material I will suggest this tho!!

 

[Leesparkykent]

When installing a new DB, where possible I would leave spare ways for future additions. If the supply for the new DB is switched through the contactor the spare ways would be basically redundant as they would be controlled via the photocell/contactor. IMO it would be prudent to put the stairwell & communal lighting on its own MCB/RCBO on The new sub board so at least any spare ways would still be useable for any future additions that don't need to be switched via the photocell/contactor.

 

[c.boy]

When installing a new DB, where possible I would leave spare ways for future additions. If the supply for the new DB is switched through the contactor the spare ways would be basically redundant as they would be controlled via the photocell/contactor. IMO it would be prudent to put the stairwell & communal lighting on its own MCB/RCBO on The new sub board so at least any spare ways would still be useable for any future additions that don't need to be switched via the photocell/contactor.

Valid point leesparkykent!!This is the designated communal lighting d/b tho,there will be spares in the board,however there isn't any space to add anymore lighting in the building!! There are another 3 d/b's and a 3 phase for the laundry rooms in the switch room. How would you do this?? As I said not had many dealings with contactors!

 

[Leesparkykent]

Valid point leesparkykent!!This is the designated communal lighting d/b tho,there will be spares in the board,however there isn't any space to add anymore lighting in the building!! There are another 3 d/b's and a 3 phase for the laundry rooms in the switch room. How would you do this?? As I said not had many dealings with contactors!

excuse the cr@p drawing. suitably rated mcb, neutral bar in sub DB. Earths omitted for clarity. Alternatively the control (photocell to coil) could be on it's own circuit if need be.

 

[c.boy]

excuse the cr@p drawing.

Thanks mate appreciate that!!cant beat a drawing!!!

 

[ImpededLoop]

Just a thought. Are any of the lights emergency lights? If so you won't be able to switch the whole board like like you propose.

 

[c.boy]

Just a thought. Are any of the lights emergency lights? If so you won't be able to switch the whole board like like you propose.

No none of the lights are emergencys on this d/b,it's a strange set up!!! They are fed from another switch room next door!! If this was the case would you have to do as leesparkykent said??the lights on one and the emergencys on another contactor?? So the emerg feed to the battery isn't interrupted?

 

[Deleted member 26818]

No, you would just bypass the contactor with the permanent live, and not bother running the neutral through the contactor.