Help with Low Voltage Lighting please

[zappastix]

Hi

Chalet bungalow - two floors - loft space positioned not above the first floor but
on the same level.

I'm installing a new bathroom in a room that wasn't a bathroom.

I want to use low voltage lighting, with individual (dimmable) transformers.

At present there is one pendant light/rose.

I will need either 7 or possibly 8 - 50 watt dichroic halogen bulbs to cover 8m2.

MY QUESTIONS

Does the following wiring sound okay?

From the ceiling rose (now inside the loft area) connect to junction box ONE
then daisy chain to junction box TWO.

From the two junction boxes run 1.5 cable to individual transformers, using
one junction box for 4 LV lights.

Or can I get away with just one junction box?

Also, I should know the answer to the following but I can't get my brain in gear;

. . . . . will the one pendent/ceiling rose support eight 50 watt bulbs?

. . . . . with the electric bill in mind - will eight 50 watt bulbs use as much power as
400 watts incandescent household bayonet bulbs?

Just two more questions;

As I understand it, if I use "dichroic" sealed units I have to install "firehoods".

Once the firehoods have been installed can I lay loft insulation over the top of these?

If not, what is the suggested 'open space' above and around each light fitting?

Many thanks in advance.

Stephen

 

[ban-all-sheds]

I want to use low voltage lighting, with individual (dimmable) transformers.

Low voltage lights don't have transformers - see //www.diynot.com/wiki/electrics:voltage-bands (yes, it does matter).

At present there is one pendant light/rose.

I will need either 7 or possibly 8 - 50 watt dichroic halogen bulbs to cover 8m2.

Doesn't the fact that you'll need 8x as many lights as you did before tell you that the lights you're planning on installing don't work very well?

From the ceiling rose (now inside the loft area) connect to junction box ONE
then daisy chain to junction box TWO.

Will these junction boxes be accessible?

From the two junction boxes run 1.5 cable to individual transformers, using
one junction box for 4 LV lights.

Or can I get away with just one junction box?

Depends on the size of the junction box and the terminals in it.

. . . . . will the one pendent/ceiling rose support eight 50 watt bulbs?

No.

. . . . . with the electric bill in mind - will eight 50 watt bulbs use as much power as
400 watts incandescent household bayonet bulbs?

Of course they will. Slightly more, in fact, because of transformer losses.

As I understand it, if I use "dichroic" sealed units I have to install "firehoods".

No.

Once the firehoods have been installed can I lay loft insulation over the top of these?

Probably not.

If not, what is the suggested 'open space' above and around each light fitting?

You can't leave them open, as that would contravene Part C. You need a sealed enclosure which provides the clearance the light manufacturer specifies.

• http://www.nhbc.co.uk/NHBCPublicati...ical/StandardsExtra/filedownload,16553,en.pdf
  
  
• Pre-formed cap to seal downlights: http://www.aico.co.uk/firecap_loftcap.htm (It's NOT a firehood....)
  
  
• IET article on installing downlighters safely

And talking of Part C - don't forget that the work you're proposing is notifiable.