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Contactor wiring?

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tomchester999

Hello

I plan to use a din rail contactor to switch off a whole lighting circuit which is currently on a 6a mcb. (want a remote switch to control whole circuit)

Can anyone explain to me exactly what way I could wire this.. haven't used contactors before..

I guess you take the power to the contactor from the original 6a mcb therefore keeping the circuit protected..?

thanks

Tom :smile:
 
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Simples!

Mount the contactor in your fuse board and run the 6amp lighting circuit through it, ( so circuit will come from 6 amp mcb through contactor and on to lights etc.

Then from another 6amp mcb you wire a control circuit out to your switch or timer or whatever, which will run back to your contactor to switch the contacts, connect the switched live to A1 live and A2 neutral on the contactor!
 
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Here is a simple diagram of what you are after.
 

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lauriehurman said:
Explain to me why the switch is on a separate MCB?
Click to expand...

I wouldnt mind also...
You would also have to switch off 2 MCB's to isolate the lighting circuit.... I dont see the point.
Wouldnt it be better and cheaper to use a fused terminal to protect the contactor rather than a MCB?
 
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he idea of the contactor is to isolate or switch higher loads, if he used the same mcb, there would be no point in using a contactor. it is probable, that the lighting is on a 16A mcb, and the contactor switching is on a 6A mcb
 
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lauriehurman said:
I don't think so.
The point of using the contactor is to remotely switch the circuit.

Laurie
Click to expand...

mmmmm

A contactor,or relay for that matter,is a means of switching a higher loaded circuit by using a control circuit to energise the coil of said relay or contactor.

eg............110v coil on 3 phase contactor with start/stop control button feeding 3 phase 7.5kw motor pulling 13amps/phase.
Coil protected by 2 amp fuse.
Motor protected by in line overload relay.
Basic explanation but same principle for higher loaded circuits.
 
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Brilliant. I remember when I first encountered contactors. A bit like two way switching, Some get it quickly, others struggle.

Although I 'got' two way switching quite quickly, getting my head around contactors took a bit longer.

So here is my two-penneth worth.

A contactor is two switches. 1. The main load is 'switched' on and off via the 'contacts'.


2. The contacts are switched by energising (switching on) the coil within the contactor itself.

You will notice that a contactor has two different sets of inputs/ outputs. One set for the 'load' circuit to be switched and another (typically labelled A1 and A2) which are the Live and neutral for the coil that 'brings in' the contacts.

The live that controls the coil itself needs to be switched from somewhere. This can be a rocker switch, PIR, time clock, photocell, etc..

The main advantage is that a low load control circuit can energise the coil, but the load being 'controlled' by the contactor can be much much higher.
 
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Am i right in thinking that you use the 6amp mcb to supply the switchgear typically rated at 10amp which in turns powers the contactor (just a bigger switch) which can then turn on or off the large capacity lighting/power load that is fed off the higher rated mcb, say 16amp.

And the reason for a setup like this would be for in an example like the OPs that a regular 10a light switch would burn out if it was switching the whole of a warehouse lights on or off
 
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RyanCheetham said:
Am i right in thinking that you use the 6amp mcb to supply the switchgear typically rated at 10amp which in turns powers the contactor (just a bigger switch) which can then turn on or off the large capacity lighting/power load that is fed off the higher rated mcb, say 16amp.

And the reason for a setup like this would be for in an example like the OPs that a regular 10a light switch would burn out if it was switching the whole of a warehouse lights on or off
Click to expand...

Yes.
The MCB for the control side of the contactor or relay (A1,A2 via switch) doesn't need to be 6a, in Domestic that's typically the smallest in normal use but in Commercial , Industrial it would be 1amp or 2amp depending on what other controls also that source.
 
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