How do Fixtures Affect Lamp Life

[peterniss]

I noticed in the TLC catalogue there is a statement that the only lamp recommended for low voltage halogen fire rated downlights is the Coolfit. My assumption is that is because the fixture is closed behind the lamp so need to project the heat down away from the fixture. Is that correct?

It made me wonder about the effect of fixture type on lamp life. Is people's experience that a closed back fire rated fixture reduces lamp life compared to a standard open one that would be better ventilated?

Cheers.

Peter

 

[333rocky333]

A cool FIT lamp will project the heat out of the fitting, to prevent the heat inside the fitting building up and affecting the fire rated material in it.

Usually aluminium coated backs are recomended.

A cool BEAM lamp projects the heat backwards into the fiting, these will ruin a fire rated downlighter but will protect the illuminated objects from heat.

 

[peterniss]

Thanks for that clarification.

What I was thinking was that with any lamp, a fire rated fitting will get hotter than an open one, and therefore the lamp will too. I was wondering whether that could affect lamp life.

 

[ericmark]

Low voltage Halogen spot lights have two bases the GZ 10 and the GU 10 the GZ 10 has a Dichroic reflector which allows heat to pass through and has a square base on the bayonet fitting the holder will also take the GU 10 lamp. The GU 10 has a tapered shoulder on the holder and only a GU 10 lamp will fit you can't physical fit a GZ 10 lamp in the holder.
With extra low voltage there are two holders GU 4 and GU 5.3 but I am unaware of any physical system to prevent you fitting the wrong type bulb. The angle of the bulbs beam can be 10°, 24°, 36°, or 60° which may also cause problems in getting correct replacement and both Low voltage and extra low voltage have LED versions but as far as I am aware the cold cathode or CFL are only available in Low voltage versions. The energy saving LED and Cold cathode are often longer and will not fit is some fitting as a result.
Low voltage is between 50 and 1000 volt ac but I am referring to 230 volt and Extra low voltage is 0 to 50 volt but I am referring to 12 volt.
Regulation 422.3.1 and 422.4.2 tell us up to 100w there must be 0.5 meters to any flammable surface. And types of lamps is also controlled by Part L see http://www.planningportal.gov.uk/england/professionals/en/4000000000563.html and 134.1.1 says we must follow manufacturers instructions.
What I can't understand all internet searches for "Cool Fit" show a GU 5.3 fitting with is 12 volt and Extra Low Voltage not Low Voltage. And it is not Dichroic and seems the same as most the others except made by Sylvania and just seems like a trade name for non Dichroic.
Eric

 

[333rocky333]

Thanks for that clarification.

What I was thinking was that with any lamp, a fire rated fitting will get hotter than an open one, and therefore the lamp will too. I was wondering whether that could affect lamp life.

Not sure ,as the lamps run so hot anyway, I would not think it would make much difference to the lamp.

http://www.lighting-fixtures-ceiling-fans.com/halogen_light_bulbs.html#whatis


It may even be the opposite, I would quess, a lamp in an open fitting in a open draughty area, may be more affected by temperature fluctuations, than a lamp running at a constant temperature

The thing to worry about though is the heat damaging the fitting or the lampholder/ wiring.

Heat proof fittings are not usually totally sealed up and usually have vent holes .

These vent holes close up with excessive heat.

Incorrect lamps could do that and then the fitting is damaged beyond repair.
Once the vents close, the heat in the fitting will then possibly build up and eventually destroy the lampholder / wiring.

That is why with the 12 volt push in lamps it is essential to fit the right lamp as they all have the same fitment.

As ericmark say's
Cool fit may only be a brand name, generally they are called Aluminium coated lamps or similar.

With Gu10 lamps it is similar, but the holders are slightly different for aluminium, to prevent the wrong lamp being installed.