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oups.com...

Lars wrote:
Here in the UK many of the desk lamps I can buy nowadays take a bulb
with an Ediscon Screw fitting. Also many wall lights for outdoor use
(sometimes with a PIR detector) take an ES fitting bulb.

Until recently all I ever needed for a general purpose light bulb was
a bayonet fitting. Now ES fittings seem to be appearing!
Pictures: http://www.bltdirect.co.uk/base.htm


Is there a particular advantage of the ES fitting over the bayonet
fitting in these sorts of applications?

Do you buy your desk lamps from IKEA? They seem to use mainly ES (E27)
and SES (E14) fittings.

In the UK screw caps are mainly used on discharge lamps, such as SON
(high pressure sodium), metal halide, mercury etc. For some reason SOX
(low pressure sodium) lamps use bayonet caps. I prefer screw caps;
they hold the lamp more securely, important with large or heavy lamps,
such as the early Philips SL ones, and contary to the experience of
others here, I find that they're less likely to stick in the holders.
ES caps here were often used for low-voltage lamps, such as those in
emergency lighting systems in public buildings, and in buses and
trains, but tungsten GLS lamps are seldom used fur thee purposes today.

SOX lamps are fundamentally a Philips technology and they have traditionally
used a bayonet cap. I think it is also used to position the lamp in some
fixtures since the lamp light output distribution is assymetric. SON lamps
were first appeared commercially in N.A. and so utilized the usual E39 or
Mogul Screw as did other HID lamps of the time.

Terry McGowan