Regarding the church I am upgrading wiring on is the lighting dimmer pack calls for 2-20 amp at 120v circuits input, and 4-channels output at 1200 watts 120v each. That output would seem to be a bit high for just 2-20a circuits?
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You are going to have to double check the data/instruction sheet for the dimmer packs. It may very well be that they are rated for 1200W per channel, 4 channels, but at less than 3600W _total_ output at any one time. Or it may be the case that being on a dimmer pack lets one consider the lighting 'non continuous'...or it may be the case that the dimmer pack has a built in controller that limits the output power to be less than 3600W for > 3 hours. Or it may be an error in the listing.
I would certainly double check prior to putting the dimmer pack on OCPD > the 20A listed in the instructions. It is possible that the unit is listed only for use on a 20A circuit.
Check out the listing and instructions since many dimmers are indeed rated for 100% of their rated load. Also, since these sound like thyrister based dimmers you may also need to install a 200% neutral. Check out NEC section 520 for the details.
What kind of dimmer pack is this? I sounds like one of the el cheapo dj models. The instructions read, "Just plug it into to different outlets on different breakers and you are good to go!" If you are modifing it for fixed wiring you are probally violating it's listing (if it is not an unlisted taiwan knockoff).
Most dimming kit has OCPD rated at 100% with the assumption that in a large installation that all dimmers are not pulling 100%. For example a 96 dimmer rack with 20 amp dimmers can be feed from a 400amp three phase service as per the manufacturer.
As for your dimmer, if you open it and take a look, it is two seperate devices. Each 20 amp dimmer has a scr or two, a couple of chokes and a firing circuit. Technically, you could load the each dimmer up to 100%, but if you plan to do this full time the entire installation needs to support it (100%rated OCPD in the pannel). Do not put bigger breakers in the pannel, stick with the 20amps.
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