How many Dimmer Channels ?
Sun, 22 June 2008, 07:35 pmDon Allen28 posts in thread
How many Dimmer Channels ?
Sun, 22 June 2008, 07:35 pmWith the offer of state funding in WA for amateur theatres, the decisions on what to apply for need researching and some professional advice is required to explain the theatre lighting requirements of amateur theatre groups.
One ideal "Square One" lighting design, (so called because if you put everything back to "square one" you will be able to provide good lighting for any basic production ) is to:
Divide the stage into the nine basic acting areas ie DSL, DSC, DSR, MSL, MSC, MSR, USL, USC, USR.
Allocate two key lights to each area (the McAndless method see lighting links, this takes you to 18 lights from the front. at 45 degrees to the centre of each acting area.
Allocate a back light to each acting area, directly behind the centre of each acting area, this takes another six channels
You now have an ideal lighting design that uses 24 dimmer channels for individual control of each light. In a usual amateur theatre situation, you will have to parallel lights if you have less dimmer channels.
You now need to allow three dimmer channels if you have a cyclorama and additional channels for specials, so the ideal number of channels takes you up to 36, which is three dimmer racks, of 12 channels each, with a channels capacity of 2400 watts.
Any questions ?
To cover the other half of
Mon, 23 June 2008, 08:22 amTo cover the other half of the equation the current consumption for the square one rig I described would be 24 x 650 watts = 15,600 watts which is 65 amps.
Watts = volts x amps so amps is 15,600 watts / 240 volts =65 amps
This current is spread over three phases so it is 21.6 amps per phase from what is usually a 32 amp three phase outlet.
If you were using 500 watt lamps the current consumption would be less, 24 x 500 watts = 12000 watts = 50 amps.
Then allow for four 500 watt cyc lights per colour, which is 2000 watts per colour which is 8.3 amps extra per phase for a total of 29.9 amps per phase.
The use of a square one rig allows you maximum control. For a lot of plays would not have every light on maximum as you would be creating a lighting sculpture of bright on one side and slightly less from the other side to give the time of day atmosphere and maybe only one cyc colour, say blue.
So all three dimmer racks can be fed from the one 32 amp three phase circuit breaker, providing they each have their own isolating switch as per the Health Public
buildings Act (see links). Then if someone does overload one of the three phases by not balancing their phases, an integral part on a lighting design, they will trip the circuit breaker but there is no fire risk or damage to the building wiring.