Halogen downlights

[notb665]

I would like to install 6 downlights coming off a spur which comes from 240V/50Hz mains. The best thing I could find in the DIY shops is a kit containing 3x10 Watt halogen lamps and a transformer pack (output 12V). This kit is obviously built for 3x10Watt lamps, but it says in the instructions that if you mount them on non-flammable material, you can use 3x20W bulbs. So I thought I might be able to extend this to take 6x10W rather than 3x20W (total load 60W). So I bought two packs and made it (with extra cable and terminal connectors) to take 6 bulbs. It seems to be OK when switched on, is this OK to do? The instructions don't mention what rating fuse I should have in the plug which goes into the transformer (as you have to wire the cable/power-source in yourself). What rating should I use?

Now then (!), ideally I would like a dimmer switch on these lights also. So I bought a dimmer switch for low-voltage circuits and installed it before the transformer (as after didn't seem to work). Two things: 1. With 3 lights on, the transformer made a hell of a noise, buzzing like a wasp, and the dimmer switch worked fine. 2. As I added more lights, the pitch of the buzzing from the transformer changed each time (but still buzzed like mad), and on operating the dimmer sometimes the lights 'flickered'.

Can anyone help me? I would really appreciate any advice!

 

[Big_Spark]

Let me ask you a question...or two

Did the light packs come supplied with the transformer (Tx)?

If yes, did you use one Tx for each set of three lights ( I think not from your description)

Is the Tx electronic or a wire wound one?

Check the Tx and ensure that it IS dimmable, not all are, and usually not on lights so low powered.

The dimmer will not work on the output side of the Tx as it will be rated at 230V and therefore will not pass 12V. (simple explanation)

One thing to note, Wire wound transformers are better than electronic ones, lamps last longer, the Tx rarely fails, unless seriously overloaded.

The Tx is buzzing due to ionized air molecules being accelerated in a magnetic field and also due to stress of the components.

 

[breezer]

not all transformers are dimable, sounds like you have non dimable ones.

also you should not do what you have done you said So I bought two packs and made it (with extra cable and terminal connectors) to take 6 bulbs you have put 6 x 10 watt lamps on one transformer, what was the point when you brought two kits each with transformer. you can over load the transformers causing a FIRE.

your only saving is you have asked. take the dimmer out and use an ordainairy switch , and put the other transforner in too

 

[notb665]

Thanks for your time.

Yes, the lights did come with the transformers.

I used one transformer for the 6, as I would like one dimmer switch or even just one switch (I can sacrifice the dimmer) to control all 6. (Is there a way to do this using the two transformers then?)

The Txs are electronic. The instructions say that 'this product can be used with certain dimmer switches'.

 

[Big_Spark]

All you need to do is remove three of the lights from the one transformer, connect them to the second transformer, then on the INPUT side (230V side) use a three core cable to link from the existing one you have connected in to the second one. Make sure that the earth in this link cable is connected to the Earth you folded back on the supply cable to the first transformer.

If I were you, I would consider purchasing a single wire wound transformer to control these lights, it is the better way to do it, and the transformer will last years..I have one in my garage..disconnected now, that had been in my old house for about 10 years..still works fine.

One thing to remember, take the maximum load on the transformer, all the lights combined, then double it. Do this as you will be dimming it.

From what you have said, you need a wire wound Tx capable of handling a load of up to 200W, I know double your load is only 120W, but I cannot recall seeing a wire would transformer in the 100 to 200W ranges recently.

 

[notb665]

OK thanks! Just to double check: You are saying to connect the transformers in series?

And can you tell me what rating fuse to use in the mains plug please?

 

[Big_Spark]

OK thanks! Just to double check: You are saying to connect the transformers in series?

And can you tell me what rating fuse to use in the mains plug please?

NO..Parallel

Live in to Tx1 then link from this to Tx 2
N in to Tx 1, then link to Tx 2

The fuse in the plug?????

I assume you mean fused spur, this should not be greater than 3A

 

[notb665]

So it looks like this:


________TX1____Bulb_____Bulb___Bulb
_________!
!_______TX2____Bulb_____Bulb___Bulb

Is that right?

 

[notb665]

That picture is supposed to be one power in separating into two.

 

[notb665]

3 bulbs off each transformer, yes?

 

[Big_Spark]

Notbat...That picture does not make sense.

You need to connect three lights to EACH transformer.

Link the Neutral from TX 1 to Tx 2, then do the same with the Live supply.

Obviusly do this in one piece of cable.

So it goes.

Power from Switch to Live terminal on Tx 1. Link from Live Terminal on Tx 1 to Live terminal on Tx 2.

Neutral connected to Neutral Terminal on Tx1 should then be linked to the Neutral terminal on Tx 2.

The Earth core, so far ignored, should be linked and run in the cable to Tx 2, but not connected to it..this is done so that if the cable is damaged, it should still cause a short circuit and disconnect the supply.

OK?

 

[notb665]

Thanks that's great.

If you want to know anything about guitar playing you know where I am!!!