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Halogen Downlight Bulbs 50w 12v 40 Degree Beam GY6.35 Base

Postby reillyj » Thu Jul 23, 2015 5:31 pm

Hi, I have to replace some halogen downlight bulbs in my apartment hallway. The shallow fittings have GY6.35 bases and transformers.

The spec sheet says the bulbs are QT12 Lpax 50w GY6.35 . I have searched for 50w 12w bulbs with 38/40 degree beam and a bipin gy6.35 base in DIY stores and online but cannot find halogen downlight bulbs with a 6.35 base.

Any ideas on the spec, alternatives or where to get these would be much appreciated.

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Postby ericmark » Fri Jul 24, 2015 8:30 am

The GY 6.35 base is not normally used with MR16 lamps. People seem to think MR16 refers to a 12 volt lamp with reflector with GZ4 base but the MR16 refers to the reflector only.

So with a GY 6.35 base the bulb is a simple quartz bulb it does not have a reflector in the main that is a separate item.

There have been over the years specials there is for example a GU10 L2 bulb with a hole or dimple in centre designed to get around British building regulations where holders are designed only to take energy saving lamps and also a special triple bayonet 22D bulb again designed to comply with building regulations in both cases as soon as the builders move out they are often swapped for a standard fitting so cheaper bulbs can be used. Finding GU10 L2 bulbs is therefore hard.

I would guess your in a similar situation. The extra low voltage bulbs were used to get a more precise voltage to bulbs and thicker element wire so they would be slightly brighter and last longer. With the LED there is no longer any point using extra low voltage bulbs and the whole idea of transformers except special locations like bathrooms is old hat.

Using low voltage (230) gives much more options but the degree of the beam has become a problem as many LED's have a more concentrated centre but not a defined beam like the old quartz lamps. Designed for lighting pictures on the wall often using pods and dichromic reflectors which allow heat to pass but reflect the light the 50 mm spot light has been a massive problem where used not as designed but for general lighting. And using in error a dichromic reflector can cause fires.

Although you may find the bulbs likely when they blow you will have the same problem so may be the time to swap to LED not for energy saving although they may save energy if the heat is not wanted, but for maintenance free. Other than some very cheap £1 12 volt (extra low voltage) lamps 0.58W I have not changed any LED lamps. Once fitted they seem to just go on and on.
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Postby reillyj » Sat Aug 08, 2015 10:25 pm

just back from holidays so apologies for delay in thanking you for this
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