Thursday, August 11, 2016

I Work On A ...Manlift?

     That's what they call 'em, though there isn't a pink-painted verson for us distaff-side folks; we just have to the the same blue cage-on-a-crane as the boys.  I have spent a great deal of time the last week and a half in one, doing this:
Image taken from the lift.  This is about half of the room.
     Not so much the wires: I laid out and installed the wire trays (and their hangers, safety chains/cables, etc.) and all of the AC power drops -- or 24 of 27 quad boxes, anyway, and built a few of them.  Mostly my friends and/or coworkers assembled the power drops, since they were highly specific: 17 feet long, with a "stage plug" at the far end, a kind of power connector ripe for outlawing by Nerf-the-world regulators and legislators, as it is inherently dangerous in multiple ways.

     Thus endeth today's glimpse into the exciting world of show business.

10 comments:

Fuzzy Curmudgeon said...

Never understood stage plugs -- massively antiquated technology, every one of them I've ever looked at just looked dangerous. Twist-locks would be so much more suited for the purpose, IMHO.

Roberta X said...

And, in fact, twistlocks (and Neutrik PowerCon connectors at the fixture end) are what we are moving to. Most of the wall boxes, which once held 50A (or 100A) stage plugs -- you can get a little finger in the sockets of those -- have been changed to 20A twistlocks. Overhead in the grid, with around a hundred sockets per studio to change -- and plugs to match! -- it's not happening. Probably not going to happen until they make us do so. I would not use them for a new build.

Most modern stage plugs and sockets have a hole in them so you can use a tie-wrap to keep them together. This is good, as they don't have lots of retention force.

One of the gotchas, becoming a bit less over time, is that stage lighting circuits are dimmable. Nowadays, newer lighting fixtures do this internally via network control, but lighting systems must still accommodate older fixtures. Using Edison receptacles increases the risk that someone is going to plug a vacuum cleaner or computer into a circuit dimmed to low voltage, with unhappy results. Twistlocks are a little better -- but we use 30A twistlocks for ENG truck power inlets....

Anonymous said...

How about a "Personnel Height Raising Enable-ment Device". I think "Hey! Get Phred over here. I need to reach that!" has kind of a nice ring to it, and nothing has to get painted pink. :)

Richard Tengdin said...

You can never have too many receptacles, and more circuits the better so the inevitable 'one load too many' only drops a few devices instead of many. Are you running power from A and B panels for redundant power to the devices or just a single large power panel? I do power requirements for large IT servers and storage, I'm used to seeing 4x L6-30R feeds (2N redundant) to a single rack to keep everything spinning.

Also, nice to see the cable trays ready to keep the floor neater...

Roberta X said...

We have redundant power in the form of separate UPS feeds (in addition to generator-backed commercial power) to dual-power-supply critical equipment.

Every quad box you see in that image is on a separate 20A circuit. 27 or 30 total.

Richard Tengdin said...

That's a bunch of power.... 25 KW if everything is 110VAC and redundant, and up from there. How many tons (or BTU/hr) are the AC units for the space???

My biggest question is how do you quietly move enough air to cool the space?

Roberta X said...

That's literally insignificant compared to the heat load with incandescent studio lights. It's a low-speed, high-volume system with great big horizontal pyramid-on-a-plate diffusers on the down-facing supply air outlets. Returns are open facing up, very high. We have excessive cooling for the room.

Actual demand will not be near 25 kW -- we want inadvertent breaker trips to take out the minimal number of things; and that's as much detail as I can go into at this time. If we pull as much as 5 A each on those 20A circuits, I'll be surprised.

Richard Tengdin said...

Not surprising you are trying for isolated circuits, probably helps with controlling line noise.

I forgot how much heat big studio lights can generate. Are LED lamps getting closer to the color spectrum and light levels you need, or do halogen bulbs and their brethren still rule the roost?

Roberta X said...

Oh, LEDs --- and exotic things like dimmable fluorescent lights with LED-compatible phosphors -- are there and the other studio (with an actual news set in it), is 100% non-incandescent. It is much bluer light than we're used to, more like sunlight, but you just white-balance the cameras for it and it looks great. By eye, especially early on when a single step through a doorway took you from old lighting to new lighting, it was shocking at first. Now we're all used to it.

New studio lighting is remarkably cooler. The air-conditioning is still sized for the old lights and this is proving to be a problem. Too much as as bad as not enough!

stuart said...

There's something very pleasing about nicely laid out cabling, almost a work of art.