Michael J.Kitta
New member
Is a disconnect switch needed for a stage dimming system rack that only has MLO from supplier? Should a disconnect sw be located beside this dimming rack?
Yes, because people will want to switch the dimmers off from time to time, one one of those times they may want to do it in a hurry.Should a disconnect sw be located beside this dimming rack?
dimming racks are subject to article 520, and part IV of 408.
i don't see where you're required to install a disconnect @ the rack; the breaker in the MDP is all you need, and a lock-out if servicing.
I can see where it would be handy to have a disconnect (speed of show biz) but would have to check otherwise.
I looked at this thread a couple of times and wondered what was meant by "800a light dimming rack".If the customer is willing to pay for an 800A 3ph disconnect, go for it. But if I were bidding this, I wouldn't include a disconnect in the price unless the plans called for it.
I looked at this thread a couple of times and wondered what was meant by "800a light dimming rack".
Is it really 800 A 3-phase? That's an awful lot of controlled lighting.
If the dimmers are typical 2.4KW/channel dimmers (20A), then that could be as few as 120 channels if no diversity had been taken into acount. It'll probably be a lot more, as (a) most channels aren't loaded to 20A (these days more lamps are 575W than 2KW), and (b) "dimmer per socket" installations are now almost the norm, meaning that for any given production a lot less than "all" sockets (and thus dimmers) would be needed.I looked at this thread a couple of times and wondered what was meant by "800a light dimming rack".
Is it really 800 A 3-phase? That's an awful lot of controlled lighting.
. . . . when someone touches a the hot pin of a stagepin connector when he's up the top of a ladder and his other hand is on the bar...
We, as a company, make dimmers and we have some very large systems installed mostly in commercial applications like theaters and large hotels. It isn't my division of the company - we do almost exclusively industrial power electronic systems. But now and again I get called in to review the design of some of the lighting projects - usually after the event when harmonics have come to bite them in the backside.If the dimmers are typical 2.4KW/channel dimmers (20A), then that could be as few as 120 channels if no diversity had been taken into acount. It'll probably be a lot more, as (a) most channels aren't loaded to 20A (these days more lamps are 575W than 2KW), and (b) "dimmer per socket" installations are now almost the norm, meaning that for any given production a lot less than "all" sockets (and thus dimmers) would be needed.
As a user of such systems, I'd wonder why the venue would spend $$$$$ on dimmers, and then cheap out by not providing the switch that will be needed when someone touches a the hot pin of a stagepin connector when he's up the top of a ladder and his other hand is on the bar...
'cos theres plenty of old style stagepins knocking around that happily let you put the plug in wrong making the metalwork of a fixture hot. If the fixture is clamped onto a bar then theres a flash when you plug the thing in and the breaker pops. if you have the lantern in your hand however...how are they going to touch a hot pin?
Really? I guess US practice must differ from some other jurisdictions then. Permanently installed dimmers usually are in their own room, but often quite close to the stage area. Its usually accessible (ie unlocked) because even with dimmer per channel, the DMX patching often needs looking at, especially when a touring buch arrive with their own controls.Except in very old venues, I can honestly say I have never seen a stage lighting rack installed near the stage deck or a location that is open and readily accessible to make the installation any safer, in your example.
'cos theres plenty of old style stagepins knocking around that happily let you put the plug in wrong making the metalwork of a fixture hot. .
'cos theres plenty of old style stagepins knocking around that happily let you put the plug in wrong making the metalwork of a fixture hot. If the fixture is clamped onto a bar then theres a flash when you plug the thing in and the breaker pops. if you have the lantern in your hand however...
Really? I guess US practice must differ from some other jurisdictions then. Permanently installed dimmers usually are in their own room, but often quite close to the stage area.