Hi there.

I have a question regarding new :mv:lamps. Do they have an initial "break in" or run in time?

Is the lamp light output more intense for, let's say the first 200 or so hours of operation?

Reason I ask is because I just finished building and installing a 50 watt yard light and it's mega bright for the rated 1800 lumens. I hope it calms down some after a few months of dusk to dawn operation!

As mercury vapor lamp, is an unsaturated vapor HID lamp (All the mercury is in the vapour state), theoretically they don't need an initial running cycle, despite I did this with my SBMV lamps, when they were new. HPS and MH lamps more need this initial running cycle for their color to stablise, as they are considered saturated vapor lamp. In some cases, fluorescent lamps also need a running time of several hours, when operated for the first time, to get their mercury to reach equilibrum.

I don't think MV needs break in, but MH lamps are "seasoned" after about 100 Hours.

Himm I see. I thought I read that somewhere that MV lamps do this also.

The changes to full power mode would be very subtle if any, and probably not visible in respect to brightness - as even if there is some slight brightness difference, our vision "corrects" it so we still dont see anything

If anything, i'd expect to see either variations in the flicker of the lamp (rectification) or in the warm up show

If it is too bright, consider changing the ballast or adding some more ballasting impedance in series

This is where its handy to have the lumen maintenance graphs.
The standard MV lamp will drop to 90% of its original lumens at 4000 hours, (Philips lighting catalogue 1994 data for one year typical dusk to dawn running), however, you won`t see this by eye!
My current 50watt MV lamp, (French Sylvania), in my front yard light will be 2 years old this December, but still looks as bright as it was when it went in! , even though its now passed the 90% mark.

I doubt 1994 data is applicable at all to today's lamps.. Definitely not to Chinese 125's

LOL, yeah fair point, that was back when MV were built to their best!

The changes to full power mode would be very subtle if any, and probably not visible in respect to brightness - as even if there is some slight brightness difference, our vision "corrects" it so we still dont see anything

If anything, i'd expect to see either variations in the flicker of the lamp (rectification) or in the warm up show

If it is too bright, consider changing the ballast or adding some more ballasting impedance in series

What other ballast options do I have for this 50w MV lamp? If I added a resistor in series with the lamp, wouldn't the resistor get very hot to the point of failure?

This is where its handy to have the lumen maintenance graphs.
The standard MV lamp will drop to 90% of its original lumens at 4000 hours, (Philips lighting catalogue 1994 data for one year typical dusk to dawn running), however, you won`t see this by eye!
My current 50watt MV lamp, (French Sylvania), in my front yard light will be 2 years old this December, but still looks as bright as it was when it went in! , even though its now passed the 90% mark.

I see what you mean and your 50w MV yard light looks just as bright as mine does. Maybe I should switch to a clear 50w MV lamp. Would this help?

I see what you mean and your 50w MV yard light looks just as bright as mine does. Maybe I should switch to a clear 50w MV lamp. Would this help?

Well, clear MV definitely emits less light, but as well way lower CRI (barely 15), mainly there is just no red whatsoever. But if that adds the mood, it may work. Worth to try, but if you manage to still find some clear lamps...

Is there a problem with its brightness?, a neighbour issue, or just your own observation?

Is there a problem with its brightness?, a neighbour issue, or just your own observation?

To be honest, I've got no angry neighbors and the only issue I can really see is that the light does reach across the street and  lights up the front of my neighbors house slightly. Again, no complaints. So it really is just my observation.

I'm surprised that this 50 watt MV bulb/ballast is as bright as a 100w MV bulb/ballast, cannot figure out why. They both have different lumens ratings! The only advantage is that this fixture uses less power.

Better check, if the ballast really is what you expect it to be (measure the output current; a regular AC A-metter should be good enough, the current is very close to a sinewave). If it isn't by some mistake just e.g. a 70W type with a wrong label... In that case the real power will be very close to 100W, so will be the light output. Only the lamp life will be quite shorter...
The 35W MH should feed the lamp by 0.5A, the 50W MV lamp is rated for 0.6A.
A 70W MH is 0.95A, 100W MH will be around 1.25A.

Well I thought you had to let the mercury vaporize completely for a couple of hours. Because when the lamp is new the phosphor tends to be very red and when that had gone away it would run the right way.