Overloaded 12V - 300va Transformer

[JWP]

We have an old series of 12v halogen lights (11) being run by a 300va transformer in a gallery space.
I would like to get another 300va transformer to half the load for this circuit.
The current transformer has 4 wires connecting the lighting circuit to the units. The wiring is inaccessible. I'm guessing that they form 2 "rings", but will have to investigate a bit further.
What would you suggest is the best way to wire in a second transformer.

Thanks,
JWP

 

[Scoter1066]

I sincerely hope that you haven't got lights wired in a ring. Very bad form.

Are your lights 50W each?

Could you reduce the wattage by replacing for lower wattage or LEDs if the wiring is inaccessible?

Better still, if you can follow the twin & earth to each light, wire in a 60VA transformer at each point.

 

[Taylortwocities]

You need to position the second transformer half way round the line of lights, if you can.

Run a cable (twin & earth) back to the 230V input of the existing transformer.
Break the line of lights and pop the second half into the secondary (12v) side of the new transformer.

That's it.


I am wondering why you need to have a second transformer. If it is an existing, working set of lights?

 

[RF Lighting]

I very much doubt it that your lights are wired as rings.

It sounds like you might be better off finding out exactly how the existing setup is wired before anyone can really advise you further.

Try disconnecting each of the outgoing wires in turn, switch the power back on to the transformer and see how many lights do or do not come on.

Report back with your findings.

 

[PrinceofDarkness]

JWP: you didn't mention the wattages of those eleven lamps. If they're 50W each, then the 300VA transformer would indeed be overloaded - but if the circuit had been originally designed for 20W lamps, the transformer would have been comfortably loaded at 220W.

The problem with these halogen lamps is that a 20W lamp can easily be replaced by a 50W lamp, as they have the same pin dimensions.

Your existing output ('4 wires') is unlikely to be run in the form of a 'ring' - it's more likely to be two branches feeding 5+6 lamps respectively, in which case the addition of an extra 300VA transformer would be relatively simple - but have you considered fitting a modern individual electronic tranformer per fitting?


Lucia.

 

[PrinceofDarkness]

Oops, when I began this reply, there were no other replies to the O/P. So, apologies for any duplication.....


Lucia.

 

[JWP]

Thanks for all the input everyone...

As someone mentioned, the circuit can support 20W each, but yes, sometimes people have been replacing them with higher wattage bulbs... hence one of the reasons I wanted to make the change.
I was planing on doing the investigation suggested on working out the circuit, but haven't had a chance yet. The "branch" description is what I had in mind when I said 2 rings (sorry, I realize it didn't come out right).

I did consider the individual transformer changes but it's not cost effective in labour.

Each light fitting is a hanging brass light assembly, approx 1m (I call them the "triffids"), which are fixed to a vaulted ceiling (3M+)... lathe & plaster, with floorboards & carpet above... filled with stores! (so effectively no access)

Assuming the fault find shows the "branch" of 5-6 to be the case, I'm guessing I split the 230V input to the current TRANS, to supply the new, and split the "branches" between. Then I can still use the single circuit braker that is assigned currently to those lights?

 

[PrinceofDarkness]

Yes, you can do that (as I implied in my previous post).


Lucia.