12V Downlighting

[Tillman]

How do you wire 4 x 12V downlights ?

I thought you go from the mains cable (the cable in the rose of the original light) to the junction box and then each wire goes to a transformer then to the light. Is this the correct way to do it?

Would each light need its own transformer?

The lights are 50w.

Can the same transformer be used for LED bulbs and halogen bulbs. (I wanted to put halogen ones in for the time being as they came with the lamps and get LED bulbs at a later date).

 

[PrenticeBoyofDerry]

If you are installing 12V lamps such as MR16, then the lamp holder will take both LED and standard halogen lamps.
The same transformer can be used for a string of lights, but it must be rated correctly or you can have a pair or single lamps on transformers.
The method of installation would be to offer mains supply at the 230/240V of transformer and then the 12V (selv) connection to the lamp holders.
Be aware that any junctions or joints in cable "must" be easily accessible for inspection and testing. Even if in the ceiling/floor voids.
If you have plans on dimming theses lights you need dimmable transformers, dimmable lamps and a dimmer switch that is output rated correctly and compatible with the lamps and trany.
I assume the same switch for the ceiling rose is going to operate the downlights? If not you then need to install a switch drop.

 

[Tillman]

If you are installing 12V lamps such as MR16, then the lamp holder will take both LED and standard halogen lamps.
The same transformer can be used for a string of lights, but it must be rated correctly or you can have a pair or single lamps on transformers.
The method of installation would be to offer mains supply at the 230/240V of transformer and then the 12V (selv) connection to the lamp holders.
Be aware that any junctions or joints in cable "must" be easily accessible for inspection and testing. Even if in the ceiling/floor voids.
If you have plans on dimming theses lights you need dimmable transformers, dimmable lamps and a dimmer switch that is output rated correctly and compatible with the lamps and trany.
I assume the same switch for the ceiling rose is going to operate the downlights? If not you then need to install a switch drop.

Thanks for the reply. The lamps are GU10.

As the lamps are 50W and there are 4 of them, the transformer would have to be rated the total of what the watts are?
(4 lamps = 200 watt transformer, 2 lamps = 200w tranformer) is the right?

I am using the same switch from the ceiling rose for the lights. It is a 2 gang switch and am doing 2 sets of 4 downlights.

Silly question but a junction box would split the cable from one wire to four wires ?

Thanks

 

[ericmark]

GU10 lamps are normally low voltage (230vac) not extra low voltage (12v) as such they don't use transforms.

The 12v lamps today rarely use a simple transformer. They use an inverter which controls the output far better. However the inverter has both a maximum and minimum output so one lamp should be greater than the minimum and all lamps less than the maximum.

With LED lamps getting an inverter with a minimum low enough is a problem hence why the GU10 lamps have replaced the extra low voltage type. Also with the GU10 you can also use cold cathode lamps as well.