Ideal length of cord for bayonet ceiling light fitting?

Traveller · 17 Apr 2011

Hi All.

If a ceiling light consists of a simple setup of a 100-120W bulb, bayonet fitting, cable, ceiling rose and a cylindrical lampshade, would anyone be able to advise me on what is the shortest length of cable that could be used to ensure that the brilliant white ceiling does not get scorched or turn yellowy after some time?

Thanks.

EFLImpudence · 17 Apr 2011

Pendants normally come with a six inch flex.

It depends what you mean by 'some time' but eventually your brilliant white ceiling will become discoloured, whether you shorten the flex or not, because of the air current produced by the heat of the lamp. That's life.

ban-all-sheds · 18 Apr 2011

17.29m.

digdilem · 18 Apr 2011

With the shift towards CFL's, they won't discolour the ceiling.

As someone slightly above the average height, don't put them too low either. Logic suggests no part of the fitting should be below 6'6", same as doorways.

ericmark · 18 Apr 2011

Looking at:-
422.4.2 Except for equipment for which an appropriate product standard Specifics requirements, a luminaire shall be kept at an adequate distance from combustible materials. Unless otherwise recommended by the manufacturer, a small spotlight or projector shall be installed at the following minimum distance from combustible materials:
(i) Rating up to 100 W 0.5 m
(ii) Over 100 and up to 300 W 0.8 m
(iii) Over 300 and up to 500 W 1.0 m

I would say 0.8 m as 120 W is a very large lamp I have never fitted over a 100W lamp in a domestic premises. Fitting a bulb in a tube shade turns it into a projector.

ebee · 18 Apr 2011

"Fitting a bulb in a tube shade turns it into a projector."

Fitting a bulb in a tube shade turns it into a GARDEN

Sorry I could not resist the temptation

bernardgreen · 18 Apr 2011

Yellowy staining is often the result of tobacco smoke being carried up to the ceiling by the convection currents of warm air from the lamp.

Best option is to declare the room as No Smoking.

Grey dis-colouring is the most common effect and is caused by dust particles being carried to the ceiling by convection currents.

One solution is to fit a "turbulator" above the lamp to disrupt the convection currents and cause them to drop some of the dust before it reaches the ceiling. This can be a simple disc about twice the diameter of the fitting and hung a few inches below the ceiling. Make it out of white or reflective material and it will also reflect light back down as useful light.

JohnW2 · 18 Apr 2011

ericmark said:
Looking at:-
422.4.2 Except for equipment for which an appropriate product standard Specifics requirements, a luminaire shall be kept at an adequate distance from combustible materials. ....I would say 0.8 m as 120 W is a very large lamp I have never fitted over a 100W lamp in a domestic premises. Fitting a bulb in a tube shade turns it into a projector.

Is this intended as an answer to the original question? Ceilings are not usually made of combustible materials. Furthermore, if we took that 0.8 m as the answer to the question, the lamp would be at chin height in many houses!

Kind Regards, John.

Buzx1313 · 18 Apr 2011

depends on the height of the ceiling

CWESPARK · 18 Apr 2011

Pretty soon you won't be able to buy traditional lamps anymore, so I wouldn't worry about it. Stick with a flex long enough to keep you from hitting your head on it, and I wouldn't use a lamp bigger than 60 watts.

CW.

ban-all-sheds · 18 Apr 2011

ebee · 18 Apr 2011

I did wonder why the 17.29M was such a precise figure

ban-all-sheds · 18 Apr 2011

ebee said:
I did wonder why the 17.29M was such a precise figure

8.1 works as well.

Traveller · 21 Apr 2011

Thanks to everyone for your helpful replies.

diynot

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Ideal length of cord for bayonet ceiling light fitting?

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