Lighting with contactors and Emergency lighting wiring

[gerard]

Hi,
As part of my college project I have to design the electrical system for a supermarket.
The florescent lights are switched using contactors. These contactors will be switched by a bank of switches at the entrance to the premises and the contactors will switch on the lights when switched. How do I go about wiring this? Also, there are emergency fittings that will require an unswitched live to feed the battery.
Can anyone recommend a way of going about this - in the simplist way possible!!!

Cheers.

 

[IQ Electrical]

Gerard, depending on how many contactors the design eventually calls for, you'll run a control circuit that will switch the coils of the contactors from the bank of switches.

Then, your contactor just sits between the distribution board and the light fittings (normally open).

So, when a switch is operated, the contactor coil pulls in, closing the contactor and energising the circuit.

The emergency feed is normally taken straight from the same overcurrent protective device as the local lighting circuit, through a key operated test switch to the emergency light fittings.

If you draw out what I've just described, you'll see it's actually very simple but long-winded in written form!

 

[gerard]

When you say the contactor sits between the distribution board and the light fittings (normally open) - do you mean the live goes through the MCB, then through the contactor to the light circuit? The contactors will be situated in the panel? If i'm including emergency lights, will I just wire my lighting circuits with 4 core cable?

 

[IQ Electrical]

When you say the contactor sits between the distribution board and the light fittings (normally open) - do you mean the live goes through the MCB, then through the contactor to the light circuit? The contactors will be situated in the panel? If i'm including emergency lights, will I just wire my lighting circuits with 4 core cable?

Yes, you can use a cable with switched live, permanent live (through keyswitch), neutral and CPC.

If it's a supermarket, you'll probably be choosing a metal trunking and conduit wiring system for durability but the essence is the same.

The contactors can be mounted adjacent to the distribution board.

What course are you doing this project for, is it 2391-20 ?

 

[gerard]

Thanks again. That's a great help. It's the Certificate in Electrical Engineering in Dublin Institute of Technology

 

[IQ Electrical]

Well good luck and enjoy it! Any other problems, post them up!

 

[gerard]

Would you put a row of 6 florescent lights on a contactor? The design current is 3.3A. Would the inrush current be too much for an ordinary switch?

 

[IQ Electrical]

Would you put a row of 6 florescent lights on a contactor? The design current is 3.3A. Would the inrush current be too much for an ordinary switch?

That's one of the reasons for choosing contactor control, your switch bank switches are only switching the coils of the contactors, not the start up and full load current of whatever load you have connected.

Watch your volt drop figures, supermarkets (as the name suggests) cover very large areas so often entail large cable runs and their associated volt drop and earth fault loop impedance figures.

 

[gerard]

OK, will do. I'm in the middle of calculating the run lengths at the moment. Thanks again

 

[Knobhead]

Hope this helps
View attachment 4745

 

[gerard]

it does! thanks for that

 

[Jwatt]

Hi Tony,

I am doing an electrical course at the moment and just seen your post re contactors and lighting for Gerard. Just a couple of really silly questions. 1. which is your neutral in the diagram? 2. It is supposed to feed the coil as a control wire along with a switched live? 3. Are your switches in the diagram intended as key switches for emergencies or for the flourescent lights. Can't think of any more silly questions. I understand the coil operation through electromagnetism and all that but i have trouble following very straightforward diagrams.

Many thanks,

Jwatt

 

[Jwatt]

[h=2]

Re: Lighting with contactors and Emergency lighting wiring[/h]

Hi Tony,

I am doing an electrical course at the moment and just seen your post re contactors and lighting for Gerard. Just a couple of really silly questions. 1. which is your neutral in the diagram? 2. It is supposed to feed the coil as a control wire along with a switched live? 3. Are your switches in the diagram intended as key switches for emergencies or for the flourescent lights. Can't think of any more silly questions. I understand the coil operation through electromagnetism and all that but i have trouble following very straightforward diagrams.

Many thanks,

Jwatt​

 

[ezzzekiel]

if your contactor requires a neutral and live then look at which wire is returning from the contactor

 

[oxocube]

If we're talking Tesco type shop, manual switching would not comply with part L bldg regs. You would need an automatic lighting control system and (from memory) there would be 3 settings 'trading' = all lights on, 'stocking' = 30% of normal lighting, 'security' = 10% normal.