Lightimg circuit

[Magnetic]

can anybody tell me, how many lights or light fittings are allowed on one circiut. for example how many lights are allowed on say the downstairs circuit, and how many on the upstairs on a domestic house? because my teacher at college say's you are only allowed 9 lights on one circuit, that confuse's me because what if you have say 5 spot lights in one room and 5 on the other, with a few in the kitchen, the hall way etc.. then would you class each room as one or would you count each light?

 

[Andy™]

no limit

 

[unshockable]

agree..just make sure that you protect the cable..remember our mision is to look after the cables, so if you put in a 6a breaker, and an rcd, even if the ******** trys to plug the house next door in to the light socket..the fuse will blow and protect the cable.

 

[Magnetic]

Thanks, but i dont understand why i was told that you could only put 9 lights on a circuit. Is he thinking of the total current that would drawn if all the lights were on?

 

[Andy™]

even allowing no diversity, 9 fittings all on at same time would mean each must be 153w (for a 6A circuit)

he's talking crap. ask him what reg says that

 

[Chr!s]

can anybody tell me, how many lights or light fittings are allowed on one circiut. for example how many lights are allowed on say the downstairs circuit, and how many on the upstairs on a domestic house? because my teacher at college say's you are only allowed 9 lights on one circuit, that confuse's me because what if you have say 5 spot lights in one room and 5 on the other, with a few in the kitchen, the hall way etc.. then would you class each room as one or would you count each light

That all depends upon the relationship between Iz In and Ib

agree..just make sure that you protect the cable..remember our mision is to look after the cables, so if you put in a 6a breaker, and an rcd, even if the ******** trys to plug the house next door in to the light socket..the fuse will blow and protect the cable

I disagree

Small over loads for long periods of time dramatically increase premature ageing and thermal damage.

We need to design circuits so that small overloads do not occur, the cable temp of 70 degrees is not to be exceeded, so we need to maintain the relationship between (it) and (ib).

 

[batty]

It all comes back to the old days when a circuit of lights had pendants so allow for 100 watts per pendant so thats 900 watt sure you could have more than that but nowadays a lot of people have downlights so you could have 18 on a circuit if they were 50 watt even more if they are 11 watt low energy also it could be a 10 amp circuit on 1.5 cable which could have a lot more lights its all about circuit design.

 

[Andy™]

I disagree

Small over loads for long periods of time dramatically increase premature ageing and thermal damage.

We need to design circuits so that small overloads do not occur, the cable temp of 70 degrees is not to be exceeded, so we need to maintain the relationship between (it) and (ib).

sorry, but i disagree.

were talking about a lighting circuit. now assuming standard of 6A MCB & 1.5 (or even 1) T&E, then an 'overload' of say 10A is still well within limits of the cable, and so it may start to get warm, but it still has a long way to go to get to 70***

 

[Chr!s]

sorry, but i disagree.were talking about a lighting circuit. now assuming standard of 6A MCB & 1.5 (or even 1) T&E, then an 'overload' of say 10A is still well within limits of the cable, and so it may start to get warm, but it still has a long way to go to get to 70***

 

[tom1]

i thought it was 100w per light and diversity was 66% of total current , so is that roughly 2000 watts for a 6 amp mcb?

 

[oktay]

all true and i agree with plumber on using formula/maths to find out what the best/safest thing to do would be.

glad i got college to teach me

 

[SPECIAL LOCATION]

can anybody tell me, how many lights or light fittings are allowed on one circuit. for example how many lights are allowed on say the downstairs circuit, and how many on the upstairs on a domestic house? because my teacher at college say's you are only allowed 9 lights on one circuit, that confuse's me because what if you have say 5 spot lights in one room and 5 on the other, with a few in the kitchen, the hall way etc.. then would you class each room as one or would you count each light?

There is NO single rule stating how many lights you can put on one circuit..

As others have said its about your design currents and cable sizes and fuse rating!

On Site Guide:-

Paragraph 7.2.3 page 55

and

Table 7.1 pages 44 & 45

give guidance for lighting circuits

BS7671

Section 559 starting page 144 - 150

is about Luminaries & Lighting installations

Section 433 starting page 73 - 74

is about Protection against overload current

Section 314 page 39

gives info about Division of installations

etc..

etc..

All these sort of bits have relevance to lighting circuits..

But you wont find anything saying you can only put 'X' light fittings on one circuit!

Historically I was told the old 5A x 240v =1200watts

so your old house with a single lighting circuit could cope with 12 x pendants

even if homeowner put 100w bulbs everywhere!

3x bedroom

1x bathroom

1x landing

1x kitchen

1x lounge

1x dining

1x hall

1x pantry

1x internal garage

= 11 light positions!

and all was good!

Never heard '9' as been any significant number?

either way 100w is a stoooopid number to use nower days...

cuz most bog standard retail outlets don't sell 100w bulbs no more!

 

[tom1]

There is NO single rule stating how many lights you can put on one circuit..As others have said its about your design currents and cable sizes and fuse rating!

On Site Guide:-

Paragraph 7.2.3 page 55

and

Table 7.1 pages 44 & 45

give guidance for lighting circuits

BS7671

Section 559 starting page 144 - 150

is about Luminaries & Lighting installations

Section 433 starting page 73 - 74

is about Protection against overload current

Section 314 page 39

gives info about Division of installations

etc..

etc..

All these sort of bits have relevance to lighting circuits..

But you wont find anything saying you can only put 'X' light fittings on one circuit!

Historically I was told the old 5A x 240v =1200watts

so your old house with a single lighting circuit could cope with 12 x pendants

even if homeowner put 100w bulbs everywhere!

3x bedroom

1x bathroom

1x landing

1x kitchen

1x lounge

1x dining

1x hall

1x pantry

1x internal garage

= 11 light positions!

and all was good!

Never heard '9' as been any significant number?

either way 100w is a stoooopid number to use nower days...

cuz most bog standard retail outlets don't sell 100w bulbs no more!

it is daft, could have a pendant with 1, 40w

or a fitting with 5, 40w