Dish readers have an expert for everything:
"Premature ignition"? Hogwash. There are two kinds of fireworks shows: Electrical and Manual. In a manual show, the shells are loaded into mortars (essentially metal tubes, buried in a pile of sand, with fuzes extending out of the mouth of the mortar) with safety covers over the end of the fuze. To fire, the cover is removed and the fuze ignited using what is essentially a highway flare. You can get two adjacent mortars going off at once by accident if a cover has fallen off ("bare match") the one next to the one you are shooting. You cannot get more than that going off at once by accident – you'd have to have multiple people with flares physically doing something.
In an electrical show, which this had to be, the various mortars are wired together via a firing box. Those are all separate circuits (unless someone seriously screws up), and each one only goes off if the switch in that circuit is thrown. That can be done by hand, or a computer program can be set up to time all the shells. If all the shells get launched at once, either the wiring was done wrong – very wrong! – or an extended series of mistakes was made writing the computer program.
In California, where these fireworks occurred, each and every show is required by law to have a licensed pyrotechnical present and supervising. Getting that license requires both classes and exams, and extensive experience working shows run by others – the whole point being to make sure accidents are minimized. With an electrical show, there are typically at least two licensed pyros checking each other's work. The number of shows which have happened at a particular location is utterly irrelevant – the folks doing the show have done it for years, in other locations, not just that particular show.
So for this kind of "premature ignition," what had to happen is one guy (who knows what he is doing and has lots of experience doing it) had to make a series of serious mistakes. And then the guy (who also knows what he is doing) has to not catch that mistake. OR, the company putting on the show had to ignore the law and send out a single person who doesn't know what they are doing. For the computer program to mess up to this extent, it pretty much had to be a deliberate programming choice (i.e. sabotage) and nobody checking the program, because the problem would leap out at anyone who saw it. Which, if that is what happened, means that figuring out what happened would take only an hour or two, at the outside, not days.
In short, it wasn't "premature ignition." It was serious human error in setting up the show. That's the only way an entire barge (let alone three!) could go off at once.
Sorry for the rant. But I've been working fireworks shows for years, and we've never had an accident like that. Double fires (as I mentioned regarding manual shows)? Maybe once or twice a show, but usually not. Low breaks (where the lift charge was not made correctly by the manufacturer – generally in China)? Yes. But more than that? Never, in over 30 years of 4th of July shows. And suggesting that this kind of "accident" is anything other than somebody actively screwing up is insulting to everybody who goes out, every year, and gets it right.
Details for the above graphic:
Here's the complete list of the chemical cocktails that go into different fireworks, courtesy of The Works Museum in Bloomington, Minnesota:
Electric White: White-hot metal flakes
Orange: Calcium salts
Bright Red: Strontium Carbonate
Turquoise:Copper Chloride
Purple: Strontium (red) & Copper (blue)
Silver Sparkle: Burning Aluminum or Magnesium flakes
Green: Barium Chloride
Gold: Glowing Iron or Charcoal powder
Yellow: Sodium ChlorideA lot of chloride action going on. I'm never going to look at fireworks the same again.
The Dish 