Lytlec fire rated downlights - keep failing!

[ninnage]

Am I the only person on the planet having horrendous problems with Lytlec fire rated downlights? These sort of things:-

http://www.screwfix.com/p/lytlec-fi...-12v-low-volt-fire-rated-downlight-pk10/80008

I've installed loads of them - don't know if it's just a dodgy batch but after about 18 months a LOT are starting to fail. All installed to spec obviously.

The contacts in the ceramic bulb holder start to corrode for no apparent reason and eventually the light goes out. Sometimes unplugging and re-plugging the bulb will fix it but normally only short-term. I've seen some where the corrosion has caused bad contact and arcing and the wires in the teflon sleeves has turned black. Not good!

Next question, anyone know of a source for replacement ceramic bulb holders with the teflon sleeves?

Andy

 

[ericmark]

Since the first time I came across the 12 volt two pin quartz halogen lamp back in the 1970's used in traffic lights and projectors only those with fan cooling seemed to work trouble free. With traffic lights we were forever changing the lamp holder. Any fitments which retains the heat as the traffic lights did will suffer more than those in free air.

With the introduction of the spot lamp the increased surface area did improve the situation but it has not gone away the system has never been much good. There are two basic ways around the problem.

1) Use a cooler lamp
2) Use a bayonet fitting like the GU10

One of the major problems is unlike the GZ10 and GU10 where Dichromic lamps can't be fitted into non Dichromic holders the two pins of the MR16 will accept either type of lamp so fitting a Dichromic lamp into any fitting which does not have free air at the back of the lamp for cooling will over heat the pins.

 

[ninnage]

Never knew they were used in traffic lights - interesting!

There's plenty free air around them - well, certainly within spec anyway which I think (off the top of my head) is 50mm above and 100mm around. I generally avoid putting them anywhere where they're likely to get excessively hot - tight spaces with little circulating air etc.

Surely, in the scheme of things, it would cost pennies to use bulb holders that don't corrode??

 

[bernardgreen]

The problem is that the pins and the sockets have to be electrically insulated and electrical insulation is also thermal insulation. The heat conducted out of the lamp onto its pins heats the sockets and the only way for that heat to be disipated and thus reduce the temperature of the sockets is along the wiring.

Compact fittings do not allow for even thicker wires to remove heat from the socket let alone a heat sink to disipate the heat from the pins.

 

[ninnage]

Totally get what you're saying, but I mostly fit these with 35W bulbs. They're rated to 50W. I'm fitting them in spec and they're failing after 18 months. Is that normal?

And does anyone know where you can buy replacement connectors on their own?

 

[flameport]

Spare lampholders here: http://www.toolstation.com/shop/Spare+LV+Lampholder/p99286

ericmark has mentioned the most likely cause - dichroic lamps have been fitted instead of reflector types.

Dichroics can easily be identified by holding the lamp in front of a bright light. If you can see any light through the reflector (usually it will appear pink/orange in colour), it's a dichroic lamp and therefore NOT suitable.
Aluminium reflectors are totally opaque.

 

[ninnage]

But but but... they're supplied with a 50W dichroic!

Cheers for the link though - god only knows what I was searching for before that I couldn't find these!

 

[slup]

They were supplied with the wrong lamp then... You should ask the manufacturer to replace them all!

Are you positive you didn't remove the supplied 50W aluminium reflector lamps and fit 35W dichroics...

 

[ninnage]

Honestly, I've got one in front of me now - brand new out the box (they come in packs of 10). This is the exact crappy bulb they're supplied with:-

http://www.ledgrouprobus.com/catalogue/catalogue/itemdetail.php?itemID=LCLEXNE

 

[slup]

It's no wonder all the lamp holders are fried. You need to speak to them.

 

[ninnage]

I normally replace the crappy supplied bulb with a 35W or 20W Osram but kind of assumed dichroic would be OK as that's how they're supplied - by the millions!

Oh well, lesson learned. Another product to avoid.

 

[slup]

Someone needs to tell them to stop shipping the wrong lamps with their products!

 

[securespark]

I have come across this situation loads of times.

They do need to be aluminium-backed lamps and as stated, sometimes downrated to 35W too.

Otherwise they'll pop off like Chinese firecrackers.