Lighting circuit for 11 240v 30w Halogens

[iwonbigbro]

I am replacing a single rose with an array of 240v halogen lamps. What is the best circuit to use for this type of install?

I was thinking of a ring, replacing the rose with a 4 way junction, with both ends of the ring connecting to the junction, going off to the switch/mcb.

Excuse the bad diagram, hopefully it makes sense?[/img]

 

[OwainDIYer]

A transformer with 12V halogens.

 

[iwonbigbro]

I haven't been able to find any zone 1 lights in the 12v variety that look reasonably attractive.

 

[TicklyT]

There's no need for a ring, as each 230 Volt 50 Watt lamp will draw less than 0.25 Amps, that's a total load of about 2.5 Amps, or about half the capacity of an average radial lighting circuit.

12 Volt lighting would draw a total current approaching 50 Amps if they were all connected to the same circuit.

'Daisy chaining' from lamp to lamp will mean you don't end up with an unmanageable number of cables at any one point.

Over 500 watts worth of downlights to replace a single pendant shows just what a poor job they do as general lighting.

You mention 'zone 1 lights', implying they are in a bathroom environment. Are you aware of the requirement to notify your LABC of electrical work in bathrooms?

 

[iwonbigbro]

Indeed, I have an electrician coming to rewire the kitchen, which is also governed under the same notification restriction. If I wire the bathroom lights, I will get him to certify them when he does the kitchen work.

Thanks for the info. So if I understand correctly, since watts = amps * volts, does that mean the transformers each draw more than the 50w required for each bulb?

 

[foxhole]

I would go for 12 volt led's [5watt, equivalent to about 20 watt lv lamp], can all be run from a single transformer/driver and would reduce wattage to less than 60watts, cheaper to run and you don't need to change a lamp for years.

 

[ColJack]

If I wire the bathroom lights, I will get him to certify them when he does the kitchen work.

he can't legally do that.. he can't sign to say that he designed and installed the circuit if he didn't do it..

Thanks for the info. So if I understand correctly, since watts = amps * volts, does that mean the transformers each draw more than the 50w required for each bulb?

it depends on what your question means..

since watts in = watts out, then 50W in = 50W out..
50W @ 230V = roughly 0.22A
50W @ 12V = roughly 4.2A.

so the mains side is still only drawing 0.22A, but the 12V side of the transformer is putting out 4.2A..

since nothing is perfect, there are losses within the transformer which means that although it's only supplying 50W, it's actually consuming maybe 52W.. the extra 2W is lost in heat..

BTW, you do know that we have a dedicated electrical section to the forums?

 

[iwonbigbro]

If I wire the bathroom lights, I will get him to certify them when he does the kitchen work.

he can't legally do that.. he can't sign to say that he designed and installed the circuit if he didn't do it..

Confused. Since the work is notifiable, this suggests I can submit designs myself (as a DIYer).

Part P:

"Persons who are not registered with a self-certification scheme - including DIYers - will need to notify or submit plans to a building control body, unless the work is non-notifiable as described above."

"Some DIY work will require the submission of a building notice to the local authority and the payment of a building control fee - see Q10 item 3 above."

 

[ColJack]

yes you can do it that way, but you have to pay the LABC fees for notification, he can't notify it as part of his work though..
the fees for non-qualified electricians can be in the hundreds of pounds, so for a few lights it's not really worth it..

 

[iwonbigbro]

yes you can do it that way, but you have to pay the LABC fees for notification, he can't notify it as part of his work though..
the fees for non-qualified electricians can be in the hundreds of pounds, so for a few lights it's not really worth it..

Okay, good reason not to bother!