Beam Spread Questions

[pedalinbob]

I am looking at PAR36 lamps from GE. There are several available for my application.

The issue is their literature states "spread to 10% MBCP" in both the horizontal and vertical plane.
Cross posted in incandescent forum. Sorry, mods, I wasn't sure where to post it!

For example, the PAR36 H7550 6v, 8W is listed as 3 on horizontal spread to 10% and 3 on vertical spread to 10%.

My impression is that implies a spot beam...but, what does the "3" mean? 3 degrees? 3"? 3'?

Another very similar bulb, PAR36 H7551 6v, 8w is listed at 30 spread to 10% horizontal and 20 spread to 10% vertical.

This looks like a flood beam...but how much flood?

If the numbers are degrees, I can easily compute how much spot/throw will occur over distance (or at least the beam size over distance).

Thoughts????

[Ra]

Hi pedalinbob,

They mean degrees.. 3 horizontal and 3 vertical means the beam is circular, 3 degrees wide measured over the center of the beampattern, from the two points on bothe sides from the center where the cp value is 10% of the value at the center of the beam.

Oh.. there is one thing that I'm not shure of: Weather the 3 degrees is the total beamspread or from the center of the beampattern. That would give a total of 6 degrees spread.. My guess is that 3 means 3 degrees total beamspread.

So 30 horizontal and 20 vertical means a oval-shaped flood-beam of 30x20 degrees.

I hope you understand my explanation...


Regards,

Ra.