240V Halogen Spotlights

[Carl Perrin]

Please can anyone advise regarding Halogen Spots, I want to replace 11 off low voltage spots with mains voltage they are all on 1 lighting circuit is this safe to do? The reason for replacing them is a quality issue (they are very unreliable) Sorry forgot to mention 50V bulbs

 

[breezer]

and you think low voltage are unreliable?

 

[securespark]

50V bulbs

Do you mean 50W?

 

[Carl Perrin]

Yes sorry 50w bulbs

 

[Chri5]

Simple enough job to change them out, but do check new fittings are the same or larger than the hole left when the old fittings are removed.

Mains powered Gu10 x 50w tend to suffer a bit and do blow every 6-12 months depending on use.

50w x 11 = 650w or a tad over 2.8A (no calculator here), what's the MCB rating for the light cct your wiring on to?
Check the load by adding all the lights on the cct together and make sure you won't overload the cct.

Above the ceiling you will have to find the primary connection for the cct and hopefully the switch circuit will be in the same area.

Then it's just a matter of running wire from fitting 1->2->3 etc
If there is a room above the ceiling area you will need smoke / fire hoods or a fire protected GU10 fitting.

50v lamps are fed via transformers in a star wire pattern to balance the load equally, you should find 2-3 transformers which along with the old cable should be removed. Due to star wiring format new wiring will be required for all lamps other than the 1st one which will pick up the LNE and hopefully the switch wires.

 

[Carl Perrin]

Thanks CHRi5,
Seems that this is going to get more complex than I thought, All 11 existing lamps have their own transformer and I am pretty sure they are on a circuit wired from one to the next, I had the ceiling overboarded last year to enable the lights to be fitted because access from above is not a practical option (horrid 8ft x 2ft chipboard floorboards), and I thought I could use the same wiring instead of wiring from jct box to transformer wire jct box to lamp?. The reason for replacing them is the wires from the transformer/connector block to bulb holder are burning out and I read that low voltage lamps project heat backwards agains mains projecting forwards , does this make sense

 

[dingbat]

If there is a room above the ceiling area you will need smoke / fire hoods or a fire protected GU10 fitting.

No you won't. Not in a single dwelling. Have a good read of Part B

 

[ricicle]

No you won't. Not in a single dwelling. Have a good read of Part B

Here is the grey area again.On my 2391 last week the lecturers were all in agreement that firehoods(or firerated downlights) had to be fitted regardless to comply with the maintaining of fire barriers in BS 7671. Plasterboard ceilings are classed as fire barriers.Any missing would fail an inspection!

 

[dingbat]

No grey area.

The BRE have carried out research which indicates that downlighters have no significant effect on the nominal fire barrier rating of plasterboard. But, in any case, it is only compartment boundaries that have a fire rating and in a single dwelling only an integral garage ceiling with a habitable room above is classed as such a boundary.

I saw your post about your 2391 and was tempted to reply. Your tutors are correctly concerned with BS7671 regulation 527-02, but are ignoring the bit that says, "...according to the degree of fire resistance of the element concerned (if any)." That necessity is not defined in BS7671, but in the Building Regulations.

To rate a domestic installation as 'unsatisfactory' because the kitchen downlights were not 'hooded' would be totally incorrect.

That said, of course, many building inspectors seem to have made up their own regulations as well, so it is wise if installing to check what your LABC has to say about it. And at the end of it all, downlights with integral fire/acoustic containment properties are never going to be a bad idea.