Wiring lighting bar DIN

[dansleeth]

Morning all,

Quick backstory: I work in a school. 10 years ago, the school specialised in music and theatre. They had a great lighting and audio setup in their hall, using a round pin dimmer system. They had extensive building work done about 9 years ago and the contractors cut cables and pretty much destroy the system. It has not been used since. The school recently began to put on productions and it would be great if I could get a lighting system working again (on the cheap). I need to do as much of the work myself, to keep costs down, but will obviously call in electricians to connect everything up and provide the installation certificates we need.

I found these internally wired lighting bars gathering dust in the basement and would like to start by getting these up and running with some LED units. I have replaced the round pin sockets on the lighting bar with standard 13a sockets. I now need to run cable from the bar towards a fused spur, which the electrician will hopefully connect at a later date.

1. Where would the power go into the bar? I assume it goes into the DIN block, but there are no obvious terminals, so maybe just into the top, matching the live (brown) with the red?
2. Can I use 2.5 flex to connect the block to a fused spur a few meters away? There would be able 8x 100w units on the bar.

 

[Crisp image]

Good evening. It looks to me like there is 6 circuits wired there that go out to the bar. Is there no other opening or entry for the supply cables to be connected to the DIN connections? Is it possible that these were purchased and never installed?
Now the 8x!00W fixtures is what you want to put on it now but I would recommend having it wired for what ever the maximum it can take (potentially 2.4kw). This way you will not be going back some time in the future revisiting the wiring cursing yourself that you didn't do it properly in the first place.
So a quick revisit back to school and science class. Ohms law come to mind. You know V=IR or W/V=I (W=Watts, V=Voltage and I=Current) so your 800w of fixtures divided by the voltage (230v in your case)= ~3.5A. So if the regulations in the UK tell you what wire size to use for the given current then that is what you have to install. I still stand by my eailier statement about maxing it out. Another reason for this is when you are no longer there or on holiday someone will want to draw more power from a single socket than you may have wired it for. At least if you are wired correctly then if someone overloads the socket it is on them not you.
I must say I am not an electrician and there is no recommendation made on size of cable or how you go about connecting said cable. This post is to give you some food for thought and you must seek the correct information from a qualified person.
Regards
Geoff

 

[almorton]

I wouldn't use 13A connectors personally - they are fused, and if the fuse goes you have to get up to the plug and change it. Normally you'd put the circuit protection in a cabinet somewhere, one breaker per circuit, and use unfused connectors. Traditionally they were BS546 "three pin round" but these days Ceeform is common.

You might find you get a more UK centric audience on www.blue-room.org.uk - I'm on both. controlbooth has a much more USA biased flavour, although not exclusively so.

The power goes into the DIN block, one per circuit. Typically you'd put the 2.5 mm in conduit to get to the bar end.

Where in the UK are you?

 

[dansleeth]

Thanks Geoff. I see your point about future proofing the unit. Maybe solid 2.5 is a better option. I am hoping the height of the lighting bar will deter many people from adding additional load to the circuit!

Thanks almorton, I am south London. I went for the standard UK sockets, as all of the lighting units the school has purchased uses those. I'd rather avoid replacing the unit's plugs, as it will require an electrician to check it over ££ - but I completely understand the logic in doing so.

This is what was used many moons ago. Wires have been cut, fuses removed and overall I think I will just ask an electrician to add a circuit to the box below and run it to the fused spur (which is in a much more accessible location). Unless anybody sees a flaw in that logic? Thanks again all

 

[dansleeth]

So if I stick my supply L+N into 2 of the terminals at the top, that would be sufficient?

 

[Amiers]

So if I stick my supply L+N into 2 of the terminals at the top, that would be sufficient?

View attachment 23995

This is a glorified wire nut. You will need to pull 12 wires back from your panel to wire into this to make them live. That being said you mentioned LEDs so you could get away with just pulling 2 circuits and save some wire and marrying 3 circuits together as this looks to be your downstage position. While I am a firm believer in DIY, not knowing your basic components you should make friends with the local electrician and see if he will come out and give it all a look for a beer and a burger or whatever the UK version of that is. The dangers of electricity is no joke and it only needs to bite once.

 

[almorton]

That terminal block has 6 seperate lives, 6 matching neutrals and a common block for a substantial protective ground (capable of taking the full potential fault current). You'd normally 6 lives and neutrals back from the end of the bar to your cabinet with the breakers in it, or to your patch panel (which would then go back to the breakers ... ).

If you common them together you are reliant on nobody trying to pull the full 13A from each socket simultaneously. Which of course, eventually, someone will, so you need a breaker rated for the current carrying capacity of your cabling, such as a 16A breaker for the entire bar.

While you're at it, you ought to protect your circuits with RCDs or combined RCD/overcurrent breakers.

I think realistically you need to have a chat with an electrician familiar with entertainment circuits rather than domestic wiring, and see how much you can do yourself and how much needs to be done by a "competent person".

Where in South London? I'm in Caterham.

 

[dansleeth]

Wow, local. The school is in Purley.

Thank you for the info. I'd love to call our electricians in for advice, but unfortunately their wisdom comes with a price. I've already been quoted £700 to have an 8-way extension put on one of the other lighting bars (by a separate contractor). Those sort of quotes would see my budget disappear in no time. Hopefully the info you knowledgable people give me will help me sort out the easy bits and just call the competents in when I know exactly what I require.

It makes complete sense now you've told me it needed 6 feeds. I was overlooking the fact that old lights needed their own feed in order to be controlled. Too used to the luxury of DMX I guess?! Purhaps I just need a different type of block that distributes the 1 feed to all the sockets. The load will only be about 600w and I could run the single cable directly to the cabinet ready for the electricians to connect to a new breaker. Great!

 

[almorton]

Something you might need to consider is inrush current. We have colorsource spots in our theatre. In steady state, you could easily run a couple of dozen of them on a pair of 13A circuits, but due to the high surge at switch on we can only manage 6 or 7 on a single circuit, so we have a Zero88 rig switch which sequences the contactors and spreads the load so they don't all try to switch on at once - in fact if you do try to switch them on all at once the 32A (or is it 63? can't remember) breaker pops.

 

[almorton]

If you want to drop by the theatre and chat with our tech folks, we are in on Tuesday evenings (it's a volunteer run theatre and we have day jobs too) from 7:30 - drop me a PM if it sounds interesting.