"froggers" wrote
| Can anyone tell me what the typical lumen outputs of "normal" mains
| 40W / 60W / 100W bulbs are or a website ?

Referring to my "Mechanical World" Electrical Year Book the output of a lamp
in lumens will be given by 4 pi Mean Spherical Candle Power. About one-half
of one percent of the enegry input to a carbon filament lamp is radiated as
light, compared to about one and a half percent in a vacuum-type tungsten
filament lamp and about 3 percent in a large gas-filled tungsten lamp. The
efficiency rises as the size increases and the efficiency drops as the
voltage increases.

For Pendant Position Vertical, tungsten filament standard lamps not opals
(Table III)

Watts Avg Lumens per Watt
15 6.70
25 7.20
40 7.13
60 8.73
75 9.54
100 10.43
150 11.52
200 11.97
300 12.78
500 13.86
1000 15.65
1500 16.73

Table IV Typical lamp efficiencies

Lamp / Lumens per W / W per MSCP

Carbon fil, ordinary 3.0 4.2
Carbon fil, metallised 6.0 2.1
Nernst 8.5 1.5
Tantalum 8.0 1.5
Tungsten, vacuum 7.5-9.5 1.65-1.3
Tungsten, gasfilled 10-20 1.25-0.65
Open carbon arc DC 15 0.85
Open carbon arc AC 7 1.8
Enclosed carbon arc DC 9.5 1.3
Flame arc open DC 40 0.32
Magnetite arc 25 0.5
Tungsten arc 12.5 1.0
Mercury arc (in quartz) 55 0.23
Neon arc 25 035
Moore, N/CO2 8.5 1.5
ditto 3 4.2
Neon glow discharge 0.85 15

| Also what the typical light output reduction is with age of the bulbs ?

For Table III, output remains within 90% of original output within 1000 hour
rated life.

Owain