wiring for mains halogen lighting

[Jim]

This is my first post. Apologies for any mistakes.

I am installing 6 x 50W mains halogen lights into my kitchen ceiling. How should they be wired? Right now there is a single light in the middle of the ceiling and I intend to take the supply from this. My plan is to connect the supply to a junction box, then connect 5 more junction boxes and run 1 halogen light from each:

Supply -------J-------- | J----J----J----J----J----J | | | | | | L L L L L L

This way, there should be no more than 2 wires into any one terminal.

I guess the wiring between each junction box and light should be designed to withstand high temperatures ?

Also I am going to replace the current single light switch with a fancy remote control dimmer rated at 600W. (Dimmers of this rating all seem to be remote control). I live in the UK and my house was built in 1990.

What do you think ?

[Toby]

If you had chosen low voltage halogens then you would most likely have discovered the larger transformers tend to have a multiple output junction box built in. Also in this case you would have had to ensure beefy wiring to each lamp to ease your justified concern over high cable temperatures caused by the high current involved.

The mains voltage halogens will not cause any significant heat in the supply cable, but you should avoid running it directly above any other fitting and it is good practice to run this cable over any insulation. Your plan for the multiple junction boxes is sound at first glance, but one of the lights will ultimately be fed thru' 7 junction boxes. I believe reducing the number of connections between supply and the fitting is preferable. Do you plan on making the holes in your ceiling large enough to feed a junction box in?

Junctions in wiring runs should be serviceable and it should be possible to inspect them. This is a fairly flexible requirement which can be met by access through the light fittings or the floor above.

A conventional approach to installing multiple halogens is to daisy chain directly to the fittings in lines. With the mains halogens you indicate,

1.5mm T&E would be fine, this would also enable potential access to the cable junctions at each fitting.

[Al Reynolds]

My four are wired like this:

Supply ------J / \ / \ J J | | | | LL LL

Which I guess could be extended to this for six lights (4 junction boxes):

Supply ------J / \ / \ J \ | | J LL / \ / \ J J | | | | LL LL

or this (also 4 junction boxes):

Supply -------J / | \ / | \ J J J | | | | | | LL LL LL

Or even this (3 junction boxes):

Supply -------J / \ / \ J J | | | | | | LLL L LL

Most of the fittings say don't daisychain on the safety instructions. This doesn't mean you can't of course!

HTH, Al

[Jim]

Thanks to Al Reynolds for the above (especially the diagrams!). I am going to use a similar arrangement to reduce the number of junction boxes from the original 7 to perhaps 4 or 5. The manufacturers instructions make no mention of special heat resistant cable so I will be using the same 1.0mm twin and earth that is used for the rest of the upstairs lighting circuit.

On the subject of junction boxes, I toyed with the idea of using some natty little 5A jobs from B&Q. But I dropped this idea on the basis that all elements in a circuit should have a rating larger than that of the fuse or circuit breaker which protects the circuit (right ?). My lighting circuit has a 6A cct breaker. I plumped for 10A junction boxes instead.

I think daisy chaining direct is not a good idea with halogen lights.

Jim

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[Jim]

Thanks to Toby for the this follow up. I have decided to use fewer junction boxes, as per Al Reynolds' diagrams elsewhere in this thread. This should reduce the total number of connections also.

I lifted the floor in the room above, so access to the lights is not a problem. I don't need to feed the equipment through the ceiling. When the floor is replaced it will be done with small screws. This way it can be removed again for servicability as toby suggests.

The floor panel I removed was a large toungue and groove slab of chipboard, secured by about 35 x 2 inch nails. Removing it was a bigger job than doing the lights ! Why do they build houses this way ? If cars were made like this, the bonnets would be welded shut. When I upgraded some single mains sockets to double last year, I found that the box behind each socket was secured by a 4 inch roofing nail hammered into the thermalite block ! Hammered so hard that the box was distorted. Anyway, mustn't grumble.

Jim.