Same Watt bulbs differ in lumens for different voltage?

[Neondiod]

Hello CPF!

I've search the forum and read it quite a lot but never get to answer this question: Why do the same Watt incan bulbs have different lumen output for different voltages?

Ex 1 : A 20W 12V G4 bulb is rated 290 lumen, but a 25W 230V G9 bulb is only rated 190 lumen.

Ex 2: A 100W E27 120V bulb has higher rated lumens then a 100W E27 230V bulb.

Thanx in andvanced, great forum.

[holiday light express]

Different manufacturers... no UL regulating what they put on the box... different housing design...

[Neondiod]

Originally Posted by holiday light express

Different manufacturers... no UL regulating what they put on the box... different housing design...

Same manufacturer ofcourse. But a G4 and a G9 housing is quite a differ on the housing and the filament is totally differ and that's maybe why the light output is less with the higher voltage bulb?

Infact a 100W 230V bulb draw 0,44A and hence shall the filament give a resistens of 525 ohm. Where a 100W 12V bulb draw 8,3A and the filament is only 1,45 oms resistens. The low resistens filament is smaller and maybe better material and hence more effective.

[ponygt65]

Originally Posted by holiday light express

Different manufacturers... no UL regulating what they put on the box... different housing design...

That is incorrect.

A 75A/CL/130V lamp listed in OSI catalog as such:

@ 130V = 750 hours, 1190 lumens

Same lamp:

@ 120V = 910 Lumens, at 1875 hours (approx. 66 Watts).


This is due to filament resistance.