how many lights

[bullneck]

We want to light an attic room using ceiling spot lights - the only other source of light are 2 velux. The attic space is 11m long x 3.5m wide. How many spot 50w lights do we need to be sufficiently lit. Is there a rule ie 1 spot per meter etc.

[beso]

It depends on the brighness required for your intended use of the space. Google for "lighting calculator".

But why use inefficient spot lights? Fluorescent lights are more than twice the efficiency of any halogen lamp.

[sparko33]

Sorry bullneck but what you're asking is not that straight forward as you will prob require at least one new circuit (from fuse board) to gain the desired lighting levels you require to illuminate 38sq m. with 50w spots.

Since the introduction of part P building regs you are very limited as to what you can and can't do in you're own house without either notifying local building control (if doing it youreself) and paying them to inspect before and after or employing a competent person who will install and certify the new circuit/s that will be required and issue you with an EIC. (electrical installation cert)

No rules or limit as to how many spots per meter etc normally loft spaces dont have that much headroom so 1500-1800mm spacing, staggered over 2 circuits with correct dimmer switches for the type of lamps being used would look good.
Colin.

[Gok Wan]

It's simple - the answer is 23.74, I can't belive no-one got it earlier.

[Disco Fever]

Hmmmmmm that's a big room, I would put in about 24 but I would switch them with 2 or 3 switches so that they don't have to be on all at the same time to save money.

You could also down rate the lamps to 35 or 20 watts or even better go to your local wholesaler or even B&Q and get an 11 watt GU10 lamp that's called a "Megaman", these lamps put out the same light output as a 50 watt GU10 lamp but only take 11 watts each.

Or even better use the GU10 LED lamp that takes only 4 watts each but they are the same brightness as a 20 watt lamp, I have 17 of them in my kitchen and it lights up perfectly.

Can you tell i'm a sparky.....

[terence7556]

disco do those low wattage lamps also stay cool compared to the 50 watt lamps, cos it sounds like a great tip

[Disco Fever]

Yes they do Terence they are quite cool as the normal GU10 50 watt lamp can get up to a temperature of over 200C and the GU10 LED lamps get only slightly warm....