Contactors

[james king]

Hello.

I was was just thinking about contactors and wondered if it was possible to .....

3x 10a mcb supplying 3 lighting circuits is it possible to switch all 3 circuits on and off via one switch?

 

[Marvo]

It's possible but probably not good practice to have 3 circuits through a contactor when the originate from 3 separate MCB's.

 

[mayfair]

think relays might be better IMHO

 

[Guest77]

Hello.

I was was just thinking about contactors and wondered if it was possible to .....

3x 10a mcb supplying 3 lighting circuits is it possible to switch all 3 circuits on and off via one switch?

yes, but clarification of what your actually switching in regard to types of lights and enviroment would be helpful.

 

[Guest77]

think a relay might be better IMHO

why is that?

 

[Guest77]

It's possible but probably not good practice to have 3 circuits through a contactor when the originate from 3 separate MCB's.

why is that?

 

[infinity]

3 mcb's and a contractor is acceptable!? Or heating circuits for instance, one stat switching on a number of heating circuits is fine

 

[james king]

It's just an example... Just thought if it then. Only used it for switching one circuit in the past. How would this work?

 

[Guest77]

More than acceptable it is common practice throughout factories and business units in the uk. having 3 or 4 lighting circuits feeding lighting and a switch controlling the coil so last one out of the building can shut down the lot with one click is installed in thousands of business properties all over the country.

 

[davesparks]

I see no problem with doing it to be honest, the other option which I have used recently is to use a contactor to switch the feed to a group of MCBs that then feed the lights.

 

[Guest77]

To add sometimes a lighting board has it's main supply via a contactor and the coil switched from one switch so the whole dist board shuts down, never switch a neutral through the contactor on three phase though, if you use three phases of course, always make sure the neutral is permanently connected from the source to the board, otherwise you could hang the phases under fault conditions and blow all the ballasts and control gear lol

 

[Marvo]

It's possible but probably not good practice to have 3 circuits through a contactor when the originate from 3 separate MCB's.

why is that?

Single point of isolation. Depends if the MCB's are in the same DB, also light circuit neutral arrangements and whether D/P switching is necessary.

 

[GMES]

As above Mdj ^^
One switch is fine, it is only pulling the coils in.

 

[Guest77]

Single point of isolation. Depends if the MCB's are in the same DB, also light circuit neutral arrangements and whether D/P switching is necessary.

Can't see any issues myself, if the circuits are wired correctly cutting just the supply to the lights via just switch wires is no issue, if something specifically need to have the neutral broken as well then yes further thought would be required, I see your point but it is common practise for general lighting in large buildings, I prefer lots of switches or motion sensors myself, but one switch is nothing unusual over here.

 

[Darkwood]

industrial lighting often run multiple circuits through a multipole contactor using a control circuit for switching ... use a dedicated enclosure for contactors attached to lighting board using main switch as isolator .... but if not a warning label of multiple isolation points is adequate .... we have to remember here that anyone entering should be competent to do so and test first ...

 

[Knobhead]

Most of our plant lighting was fed by central panels. The TP contactors would energise banks of SP MCB’s.
Got to admit it makes me giggle sometimes when people worry about switching banks of lighting.

As for the original question, it’s not ideal but with the correct warning labels there’s nothing wrong with it. Never had a 160A fuse blow on a panel yet.

Oh No! I said put a label on it!

 

[Marvo]

Most of our plant lighting was fed by central panels. The TP contactors would energise banks of SP MCB’s.

This is the way we'd do it, a t-pole MCB supplying the contactor which in turn supplies the s-pole light circuit MCB's.

 

[james king]

Anyone have any diagrams to help me understand it more? would be helpful? what about if you want one switch to turn on 6 circuits?

 

[Darkwood]

TBH Jiga reviewing your history you have asked a large amount of what would be classed as basic knowledge questions on the forum on work you are actively carrying out, Im struggling to understand what level you are or your qualifications as the sheer quantity of basic questions implicates your either out of touch with changing regulations or your experience is limited in which case either do some refresher courses or work for a company that can guide you until your experience and competence is good.

This is not an attack at you but advice, there is a lot more to arranging a contactor controlled lighting system than just showing you a diagram of how to functionally switch the contactors allowing lighting banks to operate off one point, many other things have to be taken into account about the existing or be it new lighting install to pick the correct set-up. Simple things like spacers between contactors if you use more than on or the nature of the load to ensure correct AC rated switching is contactor switching is chosen.... all of which will make the difference between you returning back to the job replacing burnt out contactors within a year or two or having a lasting install.

Their are advanced design courses that help you if you plan on going down this road.

The Forum is here to answer your queriesin general and occasionally help you out if in a sticky situe' don't get into the habit of taking on work and trying to use our good nature to explain how to do what you should already know by taking such work on in the first place, we all go through the learning curve admittedly but your history is showing a heavy reliance on the forum to get your jobs right and this should not be the case you should already know alot of what you have asked if your actively taking the work on.

 

[Robotstar5]

Most of our plant lighting was fed by central panels. The TP contactors would energise banks of SP MCB’s.
Got to admit it makes me giggle sometimes when people worry about switching banks of lighting.

We go a stage further, most of the lighting is controlled by computer. The trackside lighting switches off during break times and end of shift, the high bay lighting switches off outside production hours just leaving pilot lighting for safety, we can override any of them if necessary.