R63 versus R64 lights?

[YAPH]

What's the difference between R63 and R64 light fittings and lamps? I
presume the numeric bit in R50, R63, R64 and R80 is a nominal diameter in
millimetres: does this mean R63 and R64 are just a mill different? Are
they in practice interchangeable?

--
John Stumbles -- http://yaph.co.uk

I used to be indecisive but now I'm not so sure

[Dave Osborne]

YAPH wrote:
> What's the difference between R63 and R64 light fittings and lamps? I
> presume the numeric bit in R50, R63, R64 and R80 is a nominal diameter in
> millimetres: does this mean R63 and R64 are just a mill different? Are
> they in practice interchangeable?
>

Yes, with Rx reflector bulbs, in Europe, the x represents the maximum
diameter in mm.

(Whereas in North America, the x represents the maximum diameter in
eighths of an inch).

With PARx bulbs, the x represents the maximum diameter in eighths of an
inch in both Europe and America. So PAR38 = 38 x 8 x 25.4 = 121mm diameter.

A quick bit of Googling shows that Osram, GE Lighting, and Philips offer
R63, but Crompton offers R64. This is why the designation R63 is more
common. They are interchangeable (but bear in mind that you can get ES
cap and SES cap in the smaller diameters)

[John Rumm]

YAPH wrote:
> What's the difference between R63 and R64 light fittings and lamps? I

1

> presume the numeric bit in R50, R63, R64 and R80 is a nominal diameter in
> millimetres: does this mean R63 and R64 are just a mill different? Are
> they in practice interchangeable?

Yup

--
Cheers,

John.

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