Discuss Lighting circuit controlled by a time clock and photo cell through a contactor in the Industrial Electrician Talk area at ElectriciansForums.net

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Hi gents,

I am going to a job to install some new external lighting on a factory on Monday. There are 5 new circuits to run in total. They want these to be controlled by a time clock an photo cell but also run through a key switch and contactor. It’s been some time since I wired contactors and was just looking for some advice on it or if someone could provide a wiring diagram I would be very grateful

Thanks in advance
 
Hi
Sorry about the bad drawing, it's one I done a few years ago but I kept it on my phone to refresh my memory as I don't wire these on a daily basis.
The neutral is in a connector block in the key switch.
Hope that helps
 
Think we need to know the purpose of the key switch. Override, means of turning them off, em ltg test facility??
 
Post #3 wires the functionality:

If [ T is On and ( P is On or K is On) ] then L is On

where T is the timer, P is the Photocell, etcetera.

As Westward10 said, what are the conditions for the states of T, P and K that cause L to illuminate?

Be sure beforehand otherwise you may have to come back and rejig the wiring. Ideally ask the client to write it down for you.
 
The purpose of the key switch is to test the emergency lights in the circuit. So when the key switch is activated the lights should enter into emergency mode.

This is part of the answer to the functionality: you now need to know how the client wants the photocell and timeswitch to work together or independently to control the lighting.

I recommend you have a go at writing an 'If'-then' statement as I did.

The way the T, P and K should be wired to control the contactor and thence the lighting can then be derived from it.

Is the emergency lighting 'maintained' or 'non-maintained'? Is it separate to the normal controlled illumination or a contributor to it?
 
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I would use a separate circuit for the control which will be the clock which controls the contactor/s via the photo cell. I assume the external lights are maintained so the permanent charge supply must not be isolated by the contactor/s so take this supply from the unswitched side of the contactor/s via an identified test facility. If you have five circuits you will probably need two suitably rated contactors and if each has emergency lighting then five test facilities.
 
On the contactor control circuit I tend to go through the p/cell first then the time clock relay as there is always a delay for the p/cell to operate .
 
I would use a separate circuit for the control which will be the clock which controls the contactor/s via the photo cell. I assume the external lights are maintained so the permanent charge supply must not be isolated by the contactor/s so take this supply from the unswitched side of the contactor/s via an identified test facility. If you have five circuits you will probably need two suitably rated contactors and if each has emergency lighting then five test facilities.
You could also put emergency lives through norm closed contractor and 1 key sw , poss more costly ??
 
Think we need to know the purpose of the key switch. Override, means of turning them off, em ltg test facility??
Hi
The means of the key switch is to over ride the photocell when fault finding. Easier and quicker to flick a key switch than get ladder out and get up to a photocell and cover it up
 
Hi
The means of the key switch is to over ride the photocell when fault finding. Easier and quicker to flick a key switch than get ladder out and get up to a photocell and cover it up
It is an emergency lighting test facility.
 
As said there is too little control information available to make a reasoned response.
This is one possible method of achieving a control method, but this may not be the control required or compliant with standards.
Lighting circuit controlled by a time clock and photo cell through a contactor Time clock photocell contactor EM lightin - EletriciansForums.net
 
Richard Burns possible method provides the control:

If[K or P or T] then L is on.

Or in prose:

If it is dark or if it is the right time the lighting will turn on; and their is the option also to use the keyswitch to manually turn the (non-emergency) lighting on .

The light fittings each have their own keyswitch to test each fittings integral emergency lighting.

'Or' requires switches in parallel and 'and' requires switches in series. Using 'brackets eg [ ...]' one can state clearly the hard-wired combinational logic required from the switches (as was done in #6 using () and [].

So how would one write down as if/then and then implement:

The non-emergency lighting is to turn on:

1. if it is dark and it is the right time,

or

2. a manually timed override (eg using a time-lag push switch - see Vacuum Time Lag Light Switch - https://www.tlc-direct.co.uk/Products/EK400A.html)?

or

2. Manually using a keyswitch.
 

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