number of lights per room (or sq metre) and building regs

Which is bullshit. Part P doesn't mention anything about this at all AFAICR.

Part L requires that a certain proportion of the mains rooms are are lit using lights of 40 lumens/watt efficiency or better, and halogens are only half this.

It's news to me that Part P says anything of the sort. You can read Part P of the Building Regulations online.

Area x candle-feet required = total nett lumens

guesstimate 66% efficiency (losses becauuse of depreciation (bulbs getting dirty) and utilisation (distribution of light from fitting and reflextivity of walls) = 2500 gross lumens. Using ordinary GLS lamps

about 2.5 100-watt lamps = 250 watts or about 8 40-watt lamps = 320 watts

Note the relative efficiency of the two schemes.

Very roughly you need 1 x floor area in sq ft in Watts of GLS lighting for living rooms using the largest available lamps; smaller lamps are less efficient in terms of lumens per watt.

Halogen spots are rather an inefficient way of lighting a room anyway, especially if they're downlighters, unless you've got a very reflective floor. Although they have quite a high output per watt, the utilisation factor is usually poor.

Owain

Find yourself an electricain who has a clue!

Don't think there is any required number of lights. There is a required proportion that must be low energy fittings in a new build though.

You sure he is Part P registered...?

Dave

says that

Or remember what (s)he probably / actually said and not just cite the only part of the regulations you remember / know about...

Could we have that again in english?

No such thing....

Ok badly worded,, but you know what I mean...

Dave

Perhaps you should learn to read...

wow! thanks very much for the replies. its not the electircian who is saying this but this guy who sort of project manages the build for the main builder. he has apparently read Part P and is claiming this is the case. he came back to me today with the following SMS:

"called bream (sic) the regs for spots. 1 per sqm not including linear around the wall"

don;t make sense to me, but this guy has been pretty annoying so far, he basically comes up with lots of problems but no solutions. gonna talk to the electrician to make sure, and i'll give building regs at the council a call when i have time as they have been pretty helpful on other stuff.

Sorry, but your sentance construction left whatever meaning you were trying to convey inaccessable to me. What were you trying to say? I presume it was an insult, but I can't tell if it was directed at the electrician, the OP, or me...

Oh, on second thoughts, don't bother.

He's not called John Prescott by any chance, is he?

LOL

Take your own advice.

On 29 Aug 2006 15:44:13 -0700, a particular chimpanzee named snipped-for-privacy@gmail.com randomly hit the keyboard and produced:

Not true. The requirements that have any bearing on lighting are Part L (Conservation of Fuel and Power), Part M (Access To and Use Of Buildings), and Part P (Electrical Safety). Part B (Fire Safety) has a bearing, but not in dwelling houses.

Part L requires a number of the lighting locations in new dwellings, extensions and material alterations to be energy efficient. It doesn't require a minimum number of lighting locations; indeed, it would defeat the object if the Requirements laid down more lights than was needed. Halogens don't count as energy efficient.

Part M governs the height of switches, and Part P governs the wiring to the lighting circuits. Neither govern the number of fittings.