Halogen Downighters - some help please!!

[shephpet01]

Looking for a bit of advice. I am in the process of replacing my existing ceiling lights with multiple recessed halogens. I live in a victorian house, so the lights are recessed into the ceiling voids, made up of plasterboard and wooden joists (quite old and messy with debris around). So far I have used mains voltage, but having read a few of the forums have some additional questions:

1. The lights are double insulated without an earth terminal. My method is to run a live and neutral off the main loop into a junction box, then split this into four or five live and neutrals, which I run to each light. Is this an acceptable method or should I use the 'daisy chain' method? I am a little concerned that I have one wire running off the loop that then splits into 5 - does this overload the wire?

2. Is there a safe limit to the length of the wires from the junction box to the lights?

3. Currently I do not have fire hoods, all the lights have a decent air space around them and there is no insulation material nearby. However, a few of the lights are close to the joists. The manufacturers installation instructions only refer to a minimum ceiling height, not distance from joists. Should I consider hoods, considering that the inside edge of the hood will also be quite close to the light and could result in it overheating and blowing more regularly.

4. Is there a limit to how many lights I can run off each loop. I have read that around 1200-1400 watts as a maximum, so assuming around 24 50w bulbs will be acceptable (not all off one spur of course!).

5. Can I dim these lights easily? I am reading that you can only dim in steps rather than gradually and smoothly. can anyone recommend a good (and smart looking) dimmer with IR capability that can be used where there are multiple switches for one light and multiple switches on the same plate but controlling separate lights.

6. Should I reconsider and use low voltage - seems like a hassle with all the transformers and complications with dimming...

Think that is it for the time being...!

 

[Steve]

1. daisy chain is best method - least number of cables into one connector. Dont try to get 5 cables into one terminal.

2. Provided you have mains voltage lights, there is no limit within the confines of the average house. When you get low voltage, the currents can get a bit stupid with multiple lights, and you have to use 10mm² cables etc

3. Fire hoods are only for use where the ceiling is fire rated. Unless you live in a flat, or are putting downlighters in your garage, this is unlikely.

4. loop? It depends on the protective device of the circuit. If this is 5A, max. wattage is 1150w. For 6A, this is 1380w. 10A (unlikely in a house) this is 2300w. Dont go changing the MCB or fuse to suit your lights though - the circuit may not have been designed with the upper ratings in mind.

5. You need a halogen rated dimmer (it will say this on it) OR a dimmer rated at twice the total wattage of lights it switches (for 500w of lamps you will need a 1000w dimmer) Read up about the halogen cycle too - dimming them may turn the bulb black after a while.

6. people say low voltage ones produce better light, but i cant tell the difference. Mains voltage is better for dimming.

and this should have been posted in electrics UK.

 

[shephpet01]

thanks...any thoughts on a good dimmer? Quite a few of the lights run off multiplke switches so wondering if this will complicate matters...