Other than the obvious, what's the difference between ETC Part# RT113 and RT115, (and RT114&RT171; RT196&HPL750/120X)? Seems incredulous that the exact same performance can be expected from lamps of different voltages.
The voltage of the supply greatly affects the performance and lifetime of lamps, therefore there are variants designed to be run at different supply voltages to enable sites to purchase lamps that match their usual site supply voltage.
Remember that the 'Nominal Volts' of your supply may not match the real voltage you see - my nominal voltage is 230VAC, but I have seen it rise to 250VAC!
For example:
If your site supply is actually 120VAC and you use 115V lamps, they will be slightly brighter than spec but have a shorter lifetime.
If you use 120V lamps on a supply of 115VAC, they will be a bit dimmer than spec and have a longer lifetime.
I would add that some sites that use ETC Sensor Dimming will set the output regulation to 115V or so and then use 120V lamps. (A little less bright but longer lamp life)
To answer your question directly: In a perfect world, 2 lamps with only a difference in voltage rating will give the same performance when given their respective voltage.
Hi Derek - the difference is - the filaments are sized slightly differently so that one achieves rated performance at 115V, the other at 120V. Historically, the 115V version came first - designed specifically for theater applications where most lamps are at the end of multiple feet of cable with multiple in-line connectors so the lamp in the fixture never sees the 120V coming out of the wall. This is great unless you are in a situation where the power is actually greater than 115V at the fixture and lamp life suffers greatly - so the 120V versions were created.
