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4K and 12K HMIs EXPLODE!


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#1 Erica W Thurlow

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Posted 07 February 2010 - 12:58 PM

Recently while working as 2nd Electric on a feature film, I witnessed an Arri 4K HMI globe explode violently right before my eyes moments after striking. The electrician that was operating the lamp did not handle it poorly nor did he have access to the globe before striking. The lamp burned all day the day before without problem. Could the globes lifespan have been the cause for explosion? In addition, a 12K was brought in to replace the 4K (all other HMIs were in play...) and moments after connecting the 12K (from a different line on the genny from the 4K, one stick of #2 5 wire banded and a 220v snakebite was used) the globe exploded! No one can figure out why this happened. Everything was connected properly and the globes were not handled. Factors include: This was an exterior and it was about 20 degrees outside. Also both lamps burned all day the day before and were then transported via scissor-lift to the exterior location. There were also 2 other 4Ks and 2 6Ks burning at the time of explosion, and they were not affected... So I don't think it was a voltage spike from the generator. After examining the damage the vendor has informed me that the 4K complete is totally shot. The head, head cable, and ballast are beyond repair. What could have caused this if there are no recognizable errors??? Anyone else ever experienced this?
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#2 Rob Vogt

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Posted 07 February 2010 - 01:17 PM

The only thing I can think of is either there was some moisture getting in either on the scissor lift or somewhere on that line, or there is something wrong with the lunch box since you had other lights going from other points off the genny.
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#3 Saul Rodgar

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Posted 07 February 2010 - 03:19 PM

Weird. I am hardly an electrician (my previous electric posts give me away :P ), but could it be that since the two lamps malfunctioned in succession, there was something wrong with some of your distro boxes that day? How were the other (ultimately left undamaged) instruments being power-routed while the two instruments exploded? I guess that I would be looking at whatever distro boxes /lunchboxes / cables, etc that the two instruments shared while they exploded . . .
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#4 Mathew Rudenberg

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Posted 07 February 2010 - 03:25 PM

Recently while working as 2nd Electric on a feature film, I witnessed an Arri 4K HMI globe explode violently right before my eyes moments after striking. The electrician that was operating the lamp did not handle it poorly nor did he have access to the globe before striking. The lamp burned all day the day before without problem. Could the globes lifespan have been the cause for explosion? In addition, a 12K was brought in to replace the 4K (all other HMIs were in play...) and moments after connecting the 12K (from a different line on the genny from the 4K, one stick of #2 5 wire banded and a 220v snakebite was used) the globe exploded! No one can figure out why this happened. Everything was connected properly and the globes were not handled. Factors include: This was an exterior and it was about 20 degrees outside. Also both lamps burned all day the day before and were then transported via scissor-lift to the exterior location. There were also 2 other 4Ks and 2 6Ks burning at the time of explosion, and they were not affected... So I don't think it was a voltage spike from the generator. After examining the damage the vendor has informed me that the 4K complete is totally shot. The head, head cable, and ballast are beyond repair. What could have caused this if there are no recognizable errors??? Anyone else ever experienced this?


I had a 6k globe explode on a night exterior recently - it was also very cold, but no rain.

We basically put it down as the lamp being so cold that the rapid heat release of the globe being struck caused too much expansion and it burst.

Don't really know what you can do about it... I know some electricians put scrims in a big lamp before turning it off so the hot wire slows the cooling and prevents the lens from shattering. We put up another light and thankfully it didn't explode.
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#5 Simon Olney

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Posted 07 February 2010 - 04:39 PM

When HMI bulbs blow it's normally 5 minutes after striking which would explain why they both blew so soon after being striked, it would be a coincidence, but stranger things have happened.

It's unlikely to be down to temperature, I've used HMIs on december nights in the new forest in freezing conditions (we had to de-ice the cars when leaving set in the morning) with no problem.
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#6 timHealy

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Posted 07 February 2010 - 04:41 PM

Sometimes a cake is just a cake ...

maybe you should play the lottery today ...

bulbs explode sometimes. Two in a row? You just got lucky. Nothing really technically wrong. Just coincidence.

best

Tim
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#7 JD Hartman

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Posted 07 February 2010 - 04:41 PM

Recently while working as 2nd Electric on a feature film, I witnessed an Arri 4K HMI globe explode violently right before my eyes moments after striking. The electrician that was operating the lamp did not handle it poorly nor did he have access to the globe before striking. The lamp burned all day the day before without problem. Could the globes lifespan have been the cause for explosion? In addition, a 12K was brought in to replace the 4K (all other HMIs were in play...) and moments after connecting the 12K (from a different line on the genny from the 4K, one stick of #2 5 wire banded and a 220v snakebite was used) the globe exploded! No one can figure out why this happened. Everything was connected properly and the globes were not handled. Factors include: This was an exterior and it was about 20 degrees outside. Also both lamps burned all day the day before and were then transported via scissor-lift to the exterior location. There were also 2 other 4Ks and 2 6Ks burning at the time of explosion, and they were not affected... So I don't think it was a voltage spike from the generator. After examining the damage the vendor has informed me that the 4K complete is totally shot. The head, head cable, and ballast are beyond repair. What could have caused this if there are no recognizable errors??? Anyone else ever experienced this?


Something is not being said. For the entire unit to be a total loss, globe, head, cable and ballast, something seriously must be wrong. I can't see how the blame could be the distro box, especially not in both cases, too coincidental. Where both ballasts run off 220v legs or just the 12k? Maybe it was rough handling of the head in both cases, shortly after being "killed", too short of a cool down? Did the 12k suffer the same damage, a total loss?
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#8 timHealy

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Posted 07 February 2010 - 04:45 PM

I know some electricians put scrims in a big lamp before turning it off so the hot wire slows the cooling and prevents the lens from shattering.


Electricians from LA do that but electricians in NY seem to differ. We take the scrims out when turning off large hmi pars so that the lens don't shatter.

Whatever works for you.

Best

Tim
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#9 JD Hartman

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Posted 08 February 2010 - 11:38 PM

Don't you just hate it when a curious thread like this one, just up and dies? I'd really like to see pictures of the head and ballast that were totalled, along with the technicians diagnosis of the cause and assessment of the damage.
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#10 Hal Smith

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Posted 09 February 2010 - 01:55 AM

Do you have any idea how many hours were on the bulbs that exploded? I had a discussion about six years ago with a High End System's technician about the MSR1200 bulbs (same technology as HMI's) in my Cyberlights. He said not to run them much past the point where they are starting to dim and shift color because there was a danger of bulb explosion when they were pushed beyond practical life span. Needless to say, a bulb explosion inside a complex piece of equipment like a Cyberlight is not a happy occurrence!
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#11 John Sprung

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Posted 09 February 2010 - 02:18 PM

Needless to say, a bulb explosion inside a complex piece of equipment like a Cyberlight is not a happy occurrence!


Back in the Bob Miller days at Paramount, he had an amusing technique for getting rid of old xenon's. There were these concrete stairs leading down to the basement of the studio theater, and he'd stand to one side of the door and toss them down the stairs, like a commando tossing a grenade. That eliminated the danger of explosion -- at least from that time onward. He'd do like 4-6 at a time, to make it worthwhile sweeping up afterward. ;-)




-- J.S.
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#12 Guy Holt

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Posted 09 February 2010 - 04:16 PM

.. bulbs explode sometimes. Two in a row? You just got lucky.


This reminds me of a story that the former tech at LTM once told me. Consider yourself lucky, he told me about a night shoot on a large feature when the bulbs of six 18k exploded - taking the lenses with them. As he explained it, the problem was that when the 18ks first came out, everyone bought them (and lamped them) at roughly the same time. So when just about all the 18ks in town were out on this one features (they had 18 on the set I think) most of the bulbs reached maturity at roughly the same time. It was a night not soon forgotten. Truth or lore? You be the judge.

Guy Holt, Gaffer, ScreenLight & Grip, Boston
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#13 timHealy

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Posted 14 February 2010 - 09:35 PM

After examining the damage the vendor has informed me that the 4K complete is totally shot. The head, head cable, and ballast are beyond repair.


Here's the key: "After examining the damage the vendor has informed me ...." If the electricians didn't see it or troubleshoot the light, the vendor may have taken it upon himself to get a whole new light on the productions company's insurance bill. Crazier things have happened.

best

Tim
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#14 Erica W Thurlow

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Posted 01 May 2010 - 02:50 AM

Don't you just hate it when a curious thread like this one, just up and dies? I'd really like to see pictures of the head and ballast that were totalled, along with the technicians diagnosis of the cause and assessment of the damage.


unfortunately, no pictures exist.

However, you will get a kick out of the technician's diagnosis. Not only does it not make sense, it is entirely inaccurate. Makes my head hurt just thinking about it. What a nightmare dealing with all this was.

I've attached the DOC file they send to production as their "official" diagnosis. They even had the audacity to include a "why we think this happened" letter indicating that the electric crew was to blame because a couple of us had holes in our glove's fingertips. Might I add that they speculated as to why our gloves were "holey" and concluded that one of us must have touched a HOT GLOBE with our leather gloves and melted them, thus causing the globes to explode. My head just about exploded when I read that. First of all, our gloves were worn from wrapping dirty 4/0 cable and stingers (the dust dried out the leather and weakened it). second of all... what kind of moron would open up a hot lamp and touch the globe, and then leave the damaged globe in the head? Even the greenest of electricians would never do that, and my crew was far from green. This vendor even tried to say that my crew was "inexperienced [which they spelled wrong in the letter] and put in positions they were not qualified to fill" Their opinion about this was formed when we returned the truck [a 10 ton that had no shelves, that's right... zero] that it was in disarray [another word they spelled wrong] and poorly packed. THE TRUCK HAD NO SHELVES. We were working with an empty shell of truck. Not to mention the difficult task it is to pack 20 tons of poop into a 10 ton truck... with no shelves. Kind of makes it hard to secure equipment. Even harder when that truck is operated by an overworked, underpaid Teamster. Whoops, I meant overpaid, and underworked. ;) JK Teamsters.

Ok, I'm done reminiscing about this nightmare now. I hope you enjoyed it.

Attached Files


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#15 Erica W Thurlow

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Posted 01 May 2010 - 02:55 AM

LOL that's awesome.
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#16 JD Hartman

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Posted 01 May 2010 - 05:35 PM

Did they include a copy of the report from the Engineer they hired? Or did they just summarize the highlights for you? If there was a tremendous voltage spike that traveled all over through the neutral, why weren't any Tungsten globes affected? Not to mention any computer equipment or even HMU's hair dryer or curling tongs?
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#17 timHealy

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Posted 11 May 2010 - 10:57 PM

Sounds like a bunch of malarky. Vendors love pointing the finger at everyone but themselves. Had a job with a generator issue that acted up when it rained. The vendor blamed the guy who did the oil change. Then the next time it rained I found a leak where water was dripping on the electronics that caused the issue.

For most major film issues, blame the guy who changed the oil on the genny.
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#18 John Sprung

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Posted 12 May 2010 - 05:08 PM

For most major film issues, blame the guy who changed the oil on the genny.


No, no, no. It's Craft Services. Blame it on the guy who didn't put enough raisins in the bran muffins.... ;-)





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#19 Jim Hyslop

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Posted 12 May 2010 - 05:57 PM

However, you will get a kick out of the technician's diagnosis. Not only does it not make sense, it is entirely inaccurate.

Well, you know what they say. If you can't dazzle them will brilliance, baffle them with bullshit.

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