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

[benkhan]

My builder/electrician is saying that Part P of building regs says that one halogen (he didn;t mention wattage) is required per square metre of room. This means in our 7.5m by 3.5m living room we would need 26 halogen spotlights which is crazy.

Anyone have experience of the building regs and.or recommended number of lights for a particular size room?

Judging by my old house where i had 6 x 50watt low voltage halogen spots in a 4.5 x 3.5 m room and that was more than sufficient, i think

1 spot per 2.5 to 3sq metres is more sensible.

[Andrew Gabriel]

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.

[Owain]

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

25' x 11' x say 6 candle-ft (brightness) = 1650 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

[John Rumm]

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.

[gort]

You sure he is Part P registered...?

Dave

[Jerry]

says that

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

[John Rumm]

Could we have that again in english?

[Andy Hall]

No such thing....

[gort]

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

Dave

[Jerry]

Perhaps you should learn to read...

[benkhan]

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.

[John Rumm]

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.

[Frank Erskine]

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

[gort]

LOL

[Jerry]

Take your own advice.

[Hugo Nebula]

On 29 Aug 2006 15:44:13 -0700, a particular chimpanzee named [e-mail] 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.