How many recessed spots can I put on a circuit

Postby Dickie boy » Sun Dec 21, 2008 8:48 pm

I want to swap some horrible flo tubes in a cricket pavilion lounge area for recessed 50w downlighters.

I normally work on the 240v x 6a = 1440w for a circuit rule. However I want to fit roughly 30 spots in this room, along with 3 or 4 wall lights. This would mean over 1600w, and would mean 2 circuits by my rule.

How does it affect the ruling if 12v downlighters were installed rather than 240v? I only ask because there is not a spare way in the consumer unit and it's a question of economics for the club.

Thanks in advance, Dickie
Dickie boy
Posts: 4
Joined: Wed Oct 08, 2008 4:13 pm


Simply Build It

Postby ericmark » Mon Dec 22, 2008 11:02 am

If the question is economics for the club then you should be looking at min of 40 lumins per watt also to conform with Part L not very helpful is after fitted you are told to replace.
With the withdraw of tungsten lamps you must ensure the change will not require new spots all over again and the very small spots if the lamp is held by the bayonet fitting will stick out needs to be held by rim. The larger units do seem to give a better spread of light 2D is quite common.
The little spots I think are ratted like many light fittings at a max of 5/6 amp which limits you MCB size and tend to have a lot more inrush than normal lamp so I would have no more than 5 per switch. Even is some one tries to turn all on together unlikely they can within the milli seconds gap required to stop tripping.
Also consider how many of the lights need to be maintained I normally consider 1 in 5 although I have seen 1 in 10 as emergency lights.
Do remember it is a public building and rules are different to domestic. Check on what insurance you require before starting.
I would not use extra low voltage inrush is higher and can't use cold cathode lamps and 3 watt LED lamps are like Toc H candles. Even the 11 watt cold cathode are a bit on dim side I would say although 11 to 16 watt does not seem much the 2D lamps seem to light the area a lot better I see now 28W and 38W versions are also available.
Do consider HF the lamps seem to stay bright longer and also last a lot longer I know the club I go to has a suspended ceiling and is considering moving to florescence units with 4 x 2 foot tubes in each so two or more circuits can be formed allowing the light level to be changed at flick of a switch. All to do with economy drive although some events need the extra light most don't and also dimming lights is a good way to tell people they are about to close the bar. Plus they want a flatter ceiling space to be able to put in insulation.

Postby Dickie boy » Mon Dec 22, 2008 9:46 pm

Thanks Eric for your thoughts. I have investigated further and have found 2 spare ways (ripped out showers, but mcb's left in board). The club wants to get away from flo and 2d fittings and inject more of a bar/pub feel to its lounge area. None of the lights need maintaining according to the BCO.
We would still like 50w downlighters and so will heed your advice and steer clear from 12v. This will mean I shall apply my rule and not exceed 1400w per circuit. Ideally we would also like them dimming, and I guess that means no more than 8 per switch (MK do a 400w dimmer)?
I assume all this sounds ok to you ?
Dickie boy
Posts: 4
Joined: Wed Oct 08, 2008 4:13 pm

Postby ericmark » Wed Dec 24, 2008 10:02 am

I hate dimming switches as inrush with spots is higher than which standard lamps and transformers also need special types plus now special systems for use with discharge lamps so it is so easy to make a mistake.
Also whole idea of quartz lamps is to have a very hot envelope which will return the tungsten back to the element running them cold can really reduce their life.
Lighting is a very big subject and in the past I have gone people like Newey And Eire to survey and give a recommendation they will often do it free of charge.

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