Downlights are melting the connections...

[sifry]

Hi,

I have spotlights/downlights throughout the house, which were installed when the house was built about four years ago (I don't know if these are low voltage or mains).

One of them has failed, and when removing the bulb I can see that the wires have melted. I replaced this with a new wired connector, but this one has also melted!

I can't really understand why one has gone and the rest are fine, should I replace the whole light fitting on the one that has gone, or replace the connector again and go for a bulb which will create less heat? Also, what type of bulb would that be?!

many thanks for any help

 

[stem]

Extra low voltage lamps will be supplied via a transformer, mains are wired directly without transformers.

Most of these types of light are designed to reflect the heat upwards away from the subject being illuminated, and if enclosed or covered with insulation they will overheat, and melt the wires, or possibly even start a fire.

The manufacturers instructions will stipulate how much clearance is required around the lamp and how far away the insulation should be.

 

[ban-all-sheds]

I have spotlights/downlights throughout the house, which were installed when the house was built about four years ago (I don't know if these are low voltage or mains).

In 4 years you've never had to replace a lamp?

 

[securespark]

In 1991, I installed SELV lighting for my Mum.

Incredibly, she still has some of the original Thorn lamps still working.

 

[RF Lighting]

I've got five SELV DLs in my bathroom that I installed about 9 years ago.

Never had a lamp fail yet.

They were all expensive bits at the time, but I think it was worth the extra.

Oh and they are on a soft start dimmer which helps.

 

[Lectrician]

Selv lamps can fire heat up or down depending on which you buy.

Some of the fire-rated downlights specifically state that the lamps are to be of the type that fires the heat down. This is due to the lamp caps failing where the heat resistant cable meets the cap.

I forget the name of the ones that fire the heat forward. I think they are branded cool fit.

 

[RF Lighting]

It's to do with the reflector type.

Lamps with dichroic reflectors send the heat up into the void, and aluminiumised reflectors send the heat down into the room.

 

[ban-all-sheds]

Cool Beam, or dichroic, lamps reflect the heat backwards.

With PAR lamps the heat and the light come out forwards.

You can put PAR lamps into luminaires designed for dichroic lamps, but not AAF, or they can get damaged.

 

[Lectrician]

JCC specify 'cool fit' lamps for their fire rating fittings. Only recently though. When they first came out they did not specify a type.

Mains voltage GU and GZ (heat back and forward respectively) have keyed bases to prevent GU being used in GZ fittings, but ELV lamps do not. You can fit the incorrect type easily.

You will find many wholesalers do not know there is a difference, and simply stock which ever they could get for the right price that month. All JCC fittings come with lamps.

I know the aluminium reflector fires the heat forward, but the glass dichroic backwards, but am sure there is a name for the two types. I think it may just be branding, but am sure there is a brand called 'cool fit' specially for enclosed ELV fittings.

 

[ban-all-sheds]

Mains voltage GU and GZ (heat back and forward respectively) have keyed bases to prevent GU being used in GZ fittings.

Other way round I'm afraid.

GU10s are PAR* and GZ10s are dichroic, and the keying stops GZ10s from fitting into GU10 lampholders, but not vice-versa, as it doesn't matter.




* Apart from the relatively recent introduction by hard-of-thinking manufacturers of dichroic GU10s...

 

[333rocky333]

I think it may just be branding, but am sure there is a brand called 'cool fit' specially for enclosed ELV fittings.

There's quite a few now with Cool Fit on the box and a drawing of a lamp with arrows showing the heat going forwards.


https://www.screwfix.com/prods/2935...-50-W-Lamp;jsessionid=RI12VLPU3Y0MUCSTHZOCFEY


Easy to get mixed up with the opposite ones though, marked Cool beam designed to light fragile objects like paintings etc.

http://www.osram.com/osram_com/Prof.../Technologies/Cool-Beam_technology/index.html

 

[Lectrician]

Mains voltage GU and GZ (heat back and forward respectively) have keyed bases to prevent GU being used in GZ fittings.

Other way round I'm afraid.

GU10s are PAR* and GZ10s are dichroic, and the keying stops GZ10s from fitting into GU10 lampholders, but not vice-versa, as it doesn't matter.




* Apart from the relatively recent introduction by hard-of-thinking manufacturers of dichroic GU10s...

Yea, I know what I meant!