Conventional Fixtures HELP! Source 4 sparks at yoke

[Ezra Newman]

Hey guys, our show opened last night and I had a problem I've never seen before.

Some context: we have Source 4 19 degree 750 watt conventional spots. Our grid that the spots are mounted on is metal pipe with a thin, easily scratched coat of paint on it. I think its not unreasonable to say that the C clamps cut through that everywhere on the grid and so any/all lights could be making an electrical connection (although there shouldn't be any power flowing through the grid, obviously).

One of our spot ops noticed a spark where the yoke bolts to the C lamp, so I turned off the light and had our spot op (carefully) unplug it. We replaced our entire lamp housing and cable assembly (plug all the way to the lamp) with a different one and turned the light back on. A little later there was another spark.

My spot op thinks it might be static or caused by metal grinding on metal but that seems somewhat unlikely to me because it's all metal parts (not static) and the light isn't that heavy or moving that fast. We've never seen this before. I cut power to all the lights in the grid at the circuit breaker when the audience left so it couldn't spark overnight.

I was thinking that its possible that a light is shorting through the grid and sparking there for some reason.

Have you ever had this problem?


Thanks.

Also posting this on safety.

 

[Ezra Newman]

Hey guys, our show opened last night and I had a problem I've never seen before.

Some context: we have Source 4 19 degree 750 watt conventional spots. Our grid that the spots are mounted on is metal pipe with a thin, easily scratched coat of paint on it. I think its not unreasonable to say that the C clamps cut through that everywhere on the grid and so any/all lights could be making an electrical connection (although there shouldn't be any power flowing through the grid, obviously).

One of our spot ops noticed a spark where the yoke bolts to the C lamp, so I turned off the light and had our spot op (carefully) unplug it. We replaced our entire lamp housing and cable assembly (plug all the way to the lamp) with a different one and turned the light back on. A little later there was another spark.

My spot op thinks it might be static or caused by metal grinding on metal but that seems somewhat unlikely to me because it's all metal parts (not static) and the light isn't that heavy or moving that fast. We've never seen this before. I cut power to all the lights in the grid at the circuit breaker when the audience left so it couldn't spark overnight.

I was thinking that its possible that a light is shorting through the grid and sparking there for some reason.

We've had two smallish sparks, its not shooting sparks or anything.

Have you ever had this problem?


Thanks.

Also posting this on lighting and electrics.

 

[Ben Stiegler]

Yes ... I had a defective three-fer stage pin splitter on the roof of an outdoor concert venue. Sparks shooting from the grid 30 mins before showtime. A very exciting day.

please use extreme caution in exploring this. The "hot grid" could be energized by something other than your stage lighting (such as house lights, hoist motor, etc.) and thus be unexpectedly dangerous to explore. Recommend a neon lamp tester, thick gloves, wooden plank to stand on, and calling in an expert if you feel at all unconfident about diagnosing.

 

[Ezra Newman]

We've had two smallish sparks, its not shooting sparks or anything.

 

[sk8rsdad]

Since the number of sparks should be zero, the size is somewhat moot. It wouldn't surprise me to learn one or more extension cords have been miswired. If everything were properly grounded then a breaker should be tripping.

 

[Ezra Newman]

Sparks shooting from the grid 30 mins before showtime. A very exciting day.

We've had a few smallish sparks between the bolt and the yoke, not shooting sparks. We replaced the plug on the lamp so I doubt it's two bad plugs. Will double check anyway.

 

[Ezra Newman]

Yeah, its still scary. Just realized that it sounded like it might be shooting sparks or something which would point to a different problem. Additional info was intended to help diagnose the problem, not say that it wasn't a big deal.

 

[DuckJordan]

It may not even be that fixture, its possible its the raceway.

 

[TimMc]

Any chance the outlet feeding this S4 is miswired?

 

[jayvee]

Ezra, your profile pic makes me think you're a student. If that's the case you shouldn't be doing any of this troubleshooting yourself - get a qualified adult and keep your hands out of the electricity. If you're the qualified adult, carry on.

 

[Ben Stiegler]

hey Ezra - we're both right here in Oakland. What's your venue? Maybe I can help you have a careful look, or at least a sniff from afar. I work with a number of the area high schools in various areas of theater and performance tech doing training, consulting, and sometimes "roll up the sleeves" work. Catch me thru [email protected]

this isn't out at Athenian, perchance? I was *just there* this past Sunday.

 

[Jay Ashworth]

this isn't out at Athenian, perchance? I was *just there* this past Sunday.

Ah... then it's *your* fault.

 

[Ben Stiegler]

just like those "chimney and roof inspectors" in Chicago and Boston ... you're giving me ideas

 

[BillConnerFASTC]

How old is building? Are dimmed outlets grounded?

 

[Ben Stiegler]

Ezra - tell us you're still alive, please? (and then, for no extra charge, I'll volunteer but not insist to tell you about my numerous near death experiences with electricity, rigging, and other moments of intense learning focus in the service of the performing arts, mostly when I had nice hair like yours that wasn't curled by electrical accidents.

 

[Ezra Newman]

Ah... then it's *your* fault.

*your fault* and it isn’t mine at all...

We’re doing into the woods XD

I’m still alive and so are our spot ops. We brought in a qualified adult, I’ll post a proper update in the morning or Sunday morning. I have pictures.... they’re a little scary, the problem got worse before it got better. Closest I’ve been to dead, and that’s saying something. Stories for another time.

I’m at Athenian... what we’re you doing out there?

 

[Ben Stiegler]

The gap year fair last Sunday. Exciting day with power shut off on campus, generator for modest AV, and very dark gym. Would have liked to see your theater!

if you are interested in paid summer tech theatre jobs in Oakland, let me know.Woodminster/ Producers Associates hires talented HS techies every year. My daughter grew into her stage management confidence in her years there.

 

[Ezra Newman]

Quite the adventure. We decided we should stop touching it after this....

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And so we brought in a professional lighting tech. We cut power to *everything* and we found this.

The spot wasn't plugged in to the burned one but was plugged into the duplex paired to it (the other plug in the duplex unit). We disassembled one of the plugs on a cable that lead to the spotlight and found that the neutral and hot wires were not wired securely at all to the pins on the plug (don't have a picture of this but you know what I mean). They came unpluged when we were working with it without us loosening the screws just as we pulled it apart.

We moved around some cables so they weren't wired to that box and figured it was ok. We avoided as much as possible touching metal elements of the light and didn't touch the grid for liability reasons, but we were pretty confident we had found the problem and sorted it as much as we could.

Second night of the show, we've flipped the breakers back on (or so we thought....) and start the run when I notice around two thirds/half of our conventionals aren't turning on.

Our power distribution works like this: we have two Strand dimmer boxes in the attic that each connect to twenty four dimmed Edison outlets in our grid (total of 48) and they have a bunch of breakers across the front (one for each outlet). I'm not in the theater right now and I don't remember the model off the top of my head.

For saftey reasons (just to cover our bases) we turned off all the dimmers in two ways while we were working before the show: we flipped all the individual dimmer's circuit breakers on the Strand unit and the six big circuit breakers that power the Strand boxes. Before the show I flipped on all the individual breakers on the bottom Strand box (except the two to that burned duplex plug from above) and the six big ones that give power to the two dimmer boxes. I forgot, however, to switch all the breakers on the dimmer boxes.

So its the opening number. We have three spot ops and two spot lights (they rotate), so I grab the off-duty spot op (who has never run the show), hand her my script with all the cues in it, and run around the house, slip back stage, through the green room, and put down the attic latter that goes up to where the Strand boxes are. I flip on all the dimmers, run back, hope no one in the audience noticed a bunch of lights flicking on.

The rest of the show doesn't run perfectly, mostly because I'm under-caffeinated and stressed, but it's fine.


...
...
...


Until my other spot op, on the other side from the sparking light, tells me that her light is making a weird noise.

That it sounds like sparks.


crap.


So I call HANDS OFF THE LIGHTS and go over there. I have about ninety seconds until the next cue, I listen to it. She's not wrong. It sounds like popping. In retrospect I think it might just have been the metal expanding as the light heats up, but really no way to be sure. I honestly don't remember the sound that well. We cut power to both spots and CAREFULLY unplug them when I notice this.

I know its a really shitty picture and I'm not in the theater to retake it, but what you can only sort of see is that the left hand side is supposed to be a square corner and the bit that sticks up at the top is supposed to be a rectangle (not round). It's melted.


Now its possible this extension just isn't rated for this many amps, but personally I doubt it. It looks like a short to me, especially because the neutral side is the melted one. The damage from before, on the other spot, was also on the neutral side (if I remember correctly we learned the hot shorted directly to nutral for spot #1, although I'm not sure).

So we decided no spots for closing night. That meant adding a few specials and refocusing a few lights.

How do you do that without touching the grid you may ask?

You cut power, hang and point it roughly in the right direction, hands off, return power, check your work, cut power, adjust, return power and check, cut power, repeat.

yayyyyyyy....


Of course, we didn't have time to write the new lights into the cues.... so we ended up busking a good deal of the show.

Last night was closing night, so I cut power at the circuit breakers to all the non-led lights and I'm not turning them back on until we get a professional electrician out.

 

[Ezra Newman]

Oh, two more things that have been bouncing around in my head:

For our last musical, around this time last year, we did something truly, profoundly stupid. This wasn't my call, but still. I should have made a bigger fuss about it being dumb.

It's opening night (because of course this problem happens opening night). We've just redone our house lights (which are just fresnels pointed at the house, we treat them like any other light from a dimming/control perspective) because we had to redo the seating. To avoid using so many dimmers we wired several lights to one outlet. Too many, it turns out. The circuit breakers flip. Our ingenious solution? Turn them down a bit, put someone up by the dimmer boxes and tell them to flip it back on if it flips off. This works fine for a little while because they only flip every now-and-again (I'm actually not sure why) and so they just flip it back.

Now, this person was not a lighting person. Their big qualification was that they weren't doing anything important. So they sat there and flipped it back when it flipped. But then it started flipping as soon as they flipped it back, so they held it in place. A few minutes later, despite them holding the circuit breaker closed the lights all cut out. I rush around and check what's happening and they tell me what they've been doing. My heart rate goes from like 90 (preshow plus somthing has gone wrong [so I guess just average preshow]) to like 120. We tell them to stop, park the house lights off, and turn on the work lights to open the house. It's fiiiiine.


We redo the cabling to not use that dimmer at all for the next night and move on. That dimmer doesn't work at all for a while even when not overloaded and the circuit breaker isn't tripped. I assumed that there was a fuse at a higher amperage in the Strand box to stop people doing exactly what we just did. I filed that into the "problem for another time" catagory of my brain and promptly forgot about it until right now because *the dimmer started working again without us doing anything*. I don't know if this is the same dimmer or not. It could have been. No idea.


The other thing on my mind:

One of our florescent work lights started flashing/flickering this week. Maybe five, ten cycles a second. No idea if its just a bad light or if it's somehow shorting through the grid. We got sparks at the spot with it both off and on.

 

[Ezra Newman]

(and then, for no extra charge, I'll volunteer but not insist to tell you about my numerous near death experiences with electricity, rigging, and other moments of intense learning focus in the service of the performing arts, mostly when I had nice hair like yours that wasn't curled by electrical accidents.

I'll take you up on that...