A fourth thing that could be the case is the dimmers can be trimmed for a
filament warming
current that is not noticed on higher wattage lamps but for something that's only 60 watts, it's enough to observe due to the size of the
filament. Such a
current is normal and protects lamp life when it jumps from zero to full - that's also why you kill the
breaker on the dimmers before opening up the
plug even if only a low
voltage.
The need for "ghost loading" (solution one) is the easiest to detect and correct for. Try putting something on the
dimmer in addition to the 60w lamp in another room. Say something 500
watt. Don't just set the ghost loading
fixture on the floor expecially pointed down, much less pointed at anything because you can realistically have a fire in an unoccupied room. Perhaps put it in the dressing room to keep it watched even than as long as someone a trusted actor can be responsible for it or more importantly trusted to keep others from playing with it.
Next you can try swapping cable as per step two with a quick direct run light board to dimmers. Even if
Microplex, you still need to be using
DMX or at least digital quality
XLR cable for this purpose. It's a computer signal that is going
thru the wires and needs a cable with appropriate resistance and shielding. Normal
microphone cable while using similar plugs don't do this well especially in long runs. The details on how the signal works is not in my expertise but doing this as advised would lead to a quick answer.
My step four would be next in detecting if it's a problem with the
dimmer or something that's normal. Try the lamp on another
dimmer channel, than another control
channel, than try it on both that are different. This will tell you if it's a
dimmer problem be it
trim or
dimmer itself.
Given it's still not the problem, and with the lamp plugged in,
meter the
voltage to the lamp. Than
meter it on a
dimmer that's part of the same
phase and
power source. All
voltage testing needs to be done with a minimum of a 75
watt load.
Packs especially
microplex dimmer packs frequently will be powering up more than one
dimmer per
power leg. The adjustments for how much
voltage goes to each of those controlled dimmers is usually modifyable by a screw
driver and located in the
dimmer somewhere between the main
breaker/
power source and where the individual breakers take over. Otherwise it's for individual breakers depending upon brand and type. In any case, it's a simple modification to the "
trim" that's necessary. If you are absolutely not trained for testing the
voltage, much less adjusting the
trim, get someone that is. For the
trim on a Micropex
dimmer, it's possible that the
trim for it requires going into the inside of the pack thus the qualified tech person to do so. If it's exposed, than adjusting for the
trim is really easy.
Get the
manual for the dimmers and it should tell how to adjust this. Just don't forget to tune the
voltage back up after you are done with the show. Otherwise you will possibly be blowing more lamps on the
dimmer plus they will not go up to full.
Trim the lamp down to a
level that's just below what you can observe to incandess while on that 60w load plus the 15 watts making it become at least 75 watts. Say a 15
watt work light somewhere off
stage. Don't
trim it all the way down. Plus any other dimmers that are on the
trim will become
dimmer so it is a factor in design and possibly re-patching to account for this. Say a
dimmer instead of going from 0 to 100 with a
trim or warming
voltage instead has a range of 10 to 100 percent. By trimming the
dimmer to zero, you are now limiting it to 90% of full when you
send it to full from the control signal. This might become a factor.
After all that's checked out, and especially if trimming the
dimmer is not an option, plus the bringing the
dimmer up to 75 or more watts in load did not solve it, it could be a bad
dimmer given especially the lamp went out on another
dimmer. But remember that the new
dimmer you put it in could also have had a differing
trim setting which is where my
line of thought lies. Only metering the
voltage while under load will be able to tell that.
How long has it been since the dimmers were maintained much less
trim levels adjusted? Could be a part of a larger problem as trimming the dimmers is normal for a service
call to them.