Thomas Alva Edison's trivia page

I got a few questions whose answers I thought might be of general interest.
So here goes:

i)  Efficiency champs.  Keep in mind that all lumens are not precisely
created equal, of course, but:

  conventional incandescent:  500PAR64, 6500 (initial) lumens, 500 watts,
    13 lumens/watt
  halogen:  50PAR30 (GE Halogen IR), 1000 lumens, 50 watts,
    20 lumens/watt
  fluorescent T12, GE Chroma 50, 1870 lumens, 40 watts,
    46.75 lumens/watt (on a ballast that only draws 40 watts, heigh ho)
  fluorescent T12, GE rare earth, 2960 lumens, 40 watts,
    74 lumens/watt (but this depends on the ballast)
  fluorescent T8, GE rare earth, electronic ballast (!), 2650 lumens, 27 watts,
    98 lumens/watt
  fluorescent compact F40/30BX/IS, electronic ballast, 2840 lumens, 30 watts,
    95 lumens/watt
  MH, E28 universal burning horizontally, 7100 lumens, 175 watts,
    41 lumens/watt
  MH, E28 universal burning VBU, 8300 lumens, 175 watts,
    47 lumens/watt
  MH, E28 horizontal [EP39 base], 11300 lumens, 175 watts,
    65 lumens/watt
  MH, E37 VBU, 31000 lumens, 400 watts,
    78 lumens/watt
  HPS, GE Deluxe Lucalox, 9135 lumens, 150 watts,
    61 lumens/watt
  HPS, GE White Lucalox, 4160 lumens, 95 watts,
    44 lumens/watt
  LPS, 19140 lumens, 135 watts,
    142 lumens/watt

ii)  Magic exploding instant suntan fire-bombs.  MH bulbs can fail
catastrophically.  Thus, you need to use them in an enclosure capable of
retaining 1100 degree C fragments.  Moreover, the enclosure should shield
the unwary from shortwave UV, as these lamps radiate very strongly in this
band if their outer envelope fails.  I quote the warning from 21 CFR
1040.30:  "This lamp can cause serious skin burn and eye inflammation from
shortwave ultraviolet radiation if outer envelope of the lamp is broken or
punctured, and the arc tube continues to operate.  Do not use where people
will remain for more than a few minutes unless adequate shielding or other
saftey precautions are used."  MH lamps are safe (no, really!) as long as
they are properly enclosed.  Other things to be aware of:  the lamps should
be turned off at least once per week for at least fifteen minutes.  You
should relamp your fixtures before the end of rated life, since failure and
catastrophic failure probability go up markedly, and light production
declines precipitously past rated life.

iii)  Horizontal vs. universal lamps.

Yes, horizontal lamps have a special base.  VBU oriented lamps do not (but
the smallest VBU lamp is 400 watts, and it sounds like most people are
using 175 watt pendants).

I hope this is helpful; several people sent me e-mail on these points, so I
thought there might be some interest in the list as a whole.

  --Martin Harriman
    martin-h at mail_utexas.edu