Under cabinet lighting wiring

[mal165]

Hi,
I'm looking for some advice regarding the installation of under cabinet lamps and a transformer which I purchased from TLC some time back. The lamps are 20 Volt G4 and the transformer is a Varilight YT150Z.
Initially I was going to use 5 lamps but this will now be increased to 9 in total, in 'blocks' of 3 ( 3 on one wall, 6 on the other wall at right angles to the first but split into 3 lamps on each side of the extraction hood). The transformer was to be mounted in free space above one of the kitchen units from a double socket which presently has the extraction hood connected to it.
I had intended controlling the lamps by using a rocker switch mounted to one of the light units on the low voltage side.
I would really appreciate your advise on how I should proceed with this installation regarding wiring to the transformer and then to the lights. I'm assuming I will need to purchase a further transformer considering the additional load The YT150Z transformer has sets of output terminals and I would appreciate some info on how these can be used.
many thanks in advance.

 

[bernardgreen]

The lamps are 20 Volt G4

The YT150Z is an electronic transformer, ( in reality a Switched Mode Power Supply SMPS ) with a 12 volt output.

I had intended controlling the lamps by using a rocker switch mounted to one of the light units on the low voltage side.

It is claimed that the YT150Z has no minimum rating so you should be able to control the lamps with switches in the 12 volt output circuit. That said some "no minimum" SMPS devices when running unloaded can create problems of excessive Radio Frequency Interference.

 

[seasickstevie]

If you're going to use two SMPS units, why not put your switch on the supply feeding both, then one switch operation will bring them all on.

Unless of course you'd rather the choice of not having them all on at once. But either way, if you switch on the load side, the units are going to be powered 24/7. Not the best arrangement.

 

[conny]

Isolating switch on the feed side with individual switches on the load side?
This would enable selective selection and complete isolation when going to bed, holiday etc.

 

[seasickstevie]

Isolating switch on the feed side with individual switches on the load side?
This would enable selective selection and complete isolation when going to bed, holiday etc.

Fail to see the advantage over a 2-gang switch on the supply.
What's the chance if they're switched off on the load side, whilst waiting for the taxi to take the family to the airport anyone's going to say "Oh I must switch off the supply to the lighting transformers"?

 

[conny]

Because as you say, if switched on the load side they will be powered 24/7. This method would allow you to stop that but also give the option that when they are switched on the load side to select individual lights. Just a suggestion.

 

[mal165]

Many thanks for the replies and sound advice. My difficulty with switching the feed side is finding somewhere to locate the switch. The kitchen walls are tiled from the worksurface to the underside of the cabinets, so running a mains cable there would present some difficulty. Any ideas / suggestions would be appreciated. I had thought about linking to the switch on the cooker hood but would need a closer look at that to see if it could be possible. I could install a switch adjacent to the kitchen light switch but that would involve a cable run of 5 to 6 metres. Would that be acceptable and if so what rating of cable would be required? Would a light switch be acceptable?
Thanks once again