Thread: downlights

Originally Posted by SteveI

We found in hot weather the transformers would switch-off with the heat overload cutoff and take 15 minutes to cool down and come back on..... again the newer more expensive models are more stable.

AAahh!! *figurative light bulb goes on....* pun intended

I have one downlight (out of 8) that is doing that... turning itself off at intervals, and then turning itself on again a little while later. I wondered why - heat protection may be the answer...

Would simple aging of the transformer also show this behaviour? The lights pre-date my ownership of the house - my guess is they were installed about 5 years with a kitchen renovation.

We just re-wired the whole house a couple of months ago, so I'm comfortable with the general electrical state of health.

(It's nice now to have earth wires on all powerpoints and non-flamable cotton-wrapped wiring...hehehe!
The safety switch earth leakage device makes me feel all warm n fuzzy inside now too. Makes it a little easier looking at the dent in the bank balance as a result.)

Cheers,
Geoff

Geoff,

The older ironcore(wire wound) transformers have a built in thermal cutoff. Obviously once the temperature reaches a certain level they shut off. This will be definately more common during warmer weather. Also insulation surrounding the T/F will increase the heat and the placement of T/F directly in line with your downlight will effect also as the radiant heat from the lamp is sent backwards through the ceiling. The easiest fix is to replace with the Electronic option which will dramatically reduce your problems. The 'cycling' effect of these T/F is purely due to heat. Australia's largest T/F manufacturers are slowly weaning themselves off these types purely for that very reason. These things were built to a price!

Hi

FWIW, I now use only the electronic (switch mode) transformers. At least now they are moderately priced.

When I was using the linear (iron core) transformer I ALWAYS mounted them vertically ie on a rafter or similar, this way the transformer body was on the side of the rafter (the longer direction pointing upward). I also added a "spacer" between the transformer and the mounting surface. The spacer was usually just a small 2x2x1cm block of wood. This allowed full air circulation around the complete transformer.

One othe point to consider with linear (iron core) transformers is that they are always using *some* electricity. This can be proved by feeling the temperature of the transformer body even when thelight is switched off - it is usually warm. This is a fact of life.

Electronic transformers do not use anything significant until they are under load

Hi,

John R Turk can get you most of the stuff but they normally deal in regular sparkey type of goods.

If you are after trade type lighting / globes etc, possible sources include Sydney Lighting ( 98318000, Blacktown ). They do counter sales.

Regards,

Theva

Just a quick question...This thread has made interesting reading.
I just replaced a dangly 100w light fixture with a $12 halogen kit from Harvey Norman Lighting.
Looks great and pretty easy to install.
Question. The old fixture used the earth cable. The new transformer only has a place for the +ve and -ve. What do I do with the earth (green/yellow)?

Secondly, the actual light sits under a pad of insulation. I guess I should cut a (say 10cm) hole in the fibreglass wad for ventilation? The transformer is just sitting on a nearby rafter about 12-15cm away so its not under or on top of the fibreglass insulation.

I don't want to start any fires by dodgy electricals, but on my extreme budget, can't afford a sparky to do it and I'm a fairly capable handyman anyway.

cheers

Hi

Originally Posted by Danster

Question. The old fixture used the earth cable. The new transformer only has a place for the +ve and -ve. What do I do with the earth (green/yellow)?

You do not (usually) use the earth wire on a low voltage downlight transformer as the transformer is (usually) double insulated. Double insulated electrical items do NOT have an earth wire. In your case I would fold the earth wire away from the light/transformer and use some insulation tape to bind it to the outside of the electrical cable. This will leave it available for any potential (though unlikely) change to a light fitting that does require an earth connection.

BTW +ve and -ve normally refer to DC voltage, ie the OUTPUT side of the transformer, NOT the AC input side. You could refer to the AC input side as "~", you will see a similar symbol on many ac inputs. Ususally a "double" version like a "wavy" equals sign.

Secondly, the actual light sits under a pad of insulation. I guess I should cut a (say 10cm) hole in the fibreglass wad for ventilation?

Yes, that is a good idea. 12v halogen globes run VERY hot and insulation coverage like this would increase the temperature of the light/fitting and shorten the globe life (which can be short enough already )

The transformer is just sitting on a nearby rafter about 12-15cm away so its not under or on top of the fibreglass insulation.

That's ok. If you have the "older" style (linear) transformer they do tend to get warm but this is not normally a problem. If you gave the newer style (switch mode or elcetronic) transformer then these only get warm when the light is in use.

Originally Posted by MrFixIt

Hi

One othe point to consider with linear (iron core) transformers is that they are always using *some* electricity. This can be proved by feeling the temperature of the transformer body even when thelight is switched off - it is usually warm. This is a fact of life.

Electronic transformers do not use anything significant until they are under load

Sorry, but I don't agree. The switch for the light circuit is on the input side of the transformer (240vac), therefore the transformer can't use any power if it has no input ie, when the lights are turned off.

This is one of the most polarised posts I have seen so far on this board so I will throw in my 2c worth. The missus and I love the downlights and are very happy with them. The 12v lights really brings out the timber floors and makes the place fell nicer compared to the old lights. We did make the mistake of the iron core transformers which cut out sometimes and also have had times when the dimmer caused the filaments to hum but since getting good bulbs we havent had any problems. The most common bulb to come in a package is the Luxman and they are the ultimate in useless. We were having one blow every 2 weeks (19 in the house in total). We tried a number of brands and settled on NEC bulbs which are cheap (compared to osram, I paid $3.80 each for 20) and we have only had one blow in the last 18 months. We use the 60 degree lights to give quite even lighting and we thought about the light placement so dont have any issues with them. I replaced the hottest transformers with electronic and have had no problems since. Our new renovation (starting in 6 weeks) will definitely have 12v downlights again.

Cheers
Wildman

Danster,

Earth wire
As per regulations (AS 3000), earth should be brought up to the transformer, you can fold it as MrFixIt advised or cut it off just outside the transformer.

Insulation
Make the hole in the insulation at least as large as the ceiling cutout hole required to install the fittings.

Regards,

Theva

My two cents

I love my dimmers set near the bed in each room with an off switch on the same plate. Get in to bed and dim to read then off without getting up.

A single light source in a kitchen is terrible. Everywhere you work you are in your own shadow. Hot lamps under a cupboard are not my go however. Set a channel in the overheads for a flouro keeping the line underneath neat.

In a roof keep insulation and bugs away from halogens with a cheap terracotta pot. Cut a cross shaped slit in the insulation and put a pot over the light. Silicone some fly screen over the hole on the pots bottom to avoid even the smell of roasting bugs. Little cheap pots at bunning are only 75cents last time i got some and are not at all heavy. Easy way to avoid smouldering smells.

To bring this topic up again, Ive just had 4 12v downlights put in my son's bedroom. We are in the process of painting and have the lights 'popped' down away from the ceiling. There's a buzzing noise coming from the transformer/s which is annoying. If i put all the lights back into their sockets it's harder to hear the buzz but it's still there. Is this normal (we've never had them before and have ordered 12 more for the rumpus room but if i have to put up with the low buz, I'm going to cancel the order)

different transformers may solve your problem some are noisier than others.

are the transformers sitting straight on the cieling panel. screwing or hanging them from the joists may shut them up a little.

I am starting into the kitchen renovation bit and have had 6 12v downlights in the plan. 3 over the work bench area and 3 over the cooktop/oven area.
My question is if I use 60 degree lights over a 900mm bench with a 2.4 ceiling height, how far apart should I place the lights for an even spread of light on the work area.
My retailer said, " they all come out of China and none are better than others"
Is this true.
He quoted me $13.95 for complete light,bulb,transformer kit. Lights are non swivel white powder coated. How's that???
Lastly are dimmers the go??

Thanks

Macca

Originally Posted by soundman

different transformers may solve your problem some are noisier than others.

are the transformers sitting straight on the cieling panel. screwing or hanging them from the joists may shut them up a little.

Thanks for the tip Soundman,

I can't put them on the joists because I can't get in to the roof. We have a flat roof with only about 30 cm roof cavity between the plaster and the colourbond. That's why they have them sitting on the plaster. I can put my hand in the hole and unplug each light and also get the transformer out if I want to.
I've just cut up some rubber underlay we had when we pulled up the carpet. I've got each transformer sitting on a piece of that cut to the right size so it's sitting on a soft rubber cushion. Turned them on again and no buzzing sound at all. Problem solved - but I'm going to insist on better quality for the rest of the house.