Akron(where I live) is undergoing a 1.1 billion dollar repair to the entire sewer system. We’re the largest polluter of the Cuyahoga river and thus Lake Erie. Storm water floods our sewage treatment plant and dumps raw sweage into the river/lake.
So, the city is torn up everywhere and lots of blasting to get down to bedrock. Thus the signs.
My Question–can cell phones and two -way radios really cause explosives to detonate? Can’t provide much more info for you.
Here’s a recent thread on that: Blasting Zone
Theoretically, yes, they can. In the real world, a cell phone is so low in power that it’s not at all likely to ever do so.
Actual statistics are hard to come by, as one of the issues is that there’s usually little to no evidence left behind to prove the case, and static electricity can also be a suspect. There are documented incidents where a two-way radio used in fairly close proximity to the explosives did result in a detonation, but then a two-way radio has a lot more transmitting power than a cell phone, and the radio was also a heck of a lot closer to the blast than a typical cell phone would be (assuming that the cell phone is being carried by someone who is not a part of the blast team).
The guys handling the explosives need to keep radios and cell phones away from their work, but the danger from someone driving by in a car is probably so low that it’s not worth worrying about.
Cell phone users as a whole are stubbornly stupid. Tell them not to operate a cell phone near medical equipment because it can harm the patient, and they still do. Tell them that it might cause their plane to crash, and the cell phones all come popping out when the plane comes in to land. It’s almost like the best way to insure a cell phone will be used in a particular location is to put a sign there saying that they are prohibited. And of course the cell phone users say that they’ve done it before and nothing bad happened, so it must be safe. By the same logic, if there’s a room with a hundred guns in it and only one is loaded, it’s perfectly safe to walk into the room and randomly pick up a gun, point it at your head, and pull the trigger. After all, you’ve done it a few times before and nothing bad happened.
Because cell phone users are idiots (or at least enough of them are to be a problem), the rest of the world has just had to cope. Medical equipment designed in the last couple of decades is specifically built with cell phone interference in mind. A lot of hospitals don’t even bother with signs any more. The electronics in planes are much better shielded. Explosives manufacturers build their detonators so that it takes a fair amount of induced RF to set them off.
All of this minimizes the risk, but it doesn’t completely eliminate it. Now, instead of a room with a hundred guns in it, you’ve got a room with a thousand guns in it. But one is still loaded, and people still insist upon going into the room and putting one of those guns to their heads. Sooner or later, some unlucky bastard is finally going to pick up that one loaded gun.
(actually the risk is a lot lower than one in a thousand, but hopefully you get my point)
Specifically focusing on explosives, a cell phone in a car driving by is so low in RF power and so far away from the explosives that it probably can’t make anything go boom, even under the weirdest of circumstances. An over-powered CB radio or ham radio might, though, and a cell phone or a radio operated by a member of the blasting crew also might cause an accident. A two-way radio is a lot more likely to be a problem than a cell phone, and static electricity is probably several orders of magnitude more likely to cause a problem than anything with RF.
I’ve heard about blasting initiation technology where you need a massive surge of high voltage and high current. I think it creates plasma that has to rupture it’s way out of an insulative liner inside the cap to set off the primary explosive. This seems like the way to go, it would be completely immune to static electricity and nearby radios because you would need both high voltage and high current or nothing will happen.
Even safer would be some kind of electrical sacrificial device that directly sets off the main charge. Then you don’t have to use sensitive explosive blasting caps at all, and nothing is going to cause an accidental detonation, you could just leave the wires loose while setting it up and not worry about it.
The technology necessary to make blast triggering immune to any sort of extraneous signal is almost trivially easy.
Which is not the same thing as saying that it’s in use everywhere.
But anyone doing blasting that could actually be accidentally set off by comm radios or mobile phones is using technology that’s more or less criminally primitive.
I finished off the last 7 years or so in the Army as a combat engineer. No one gave a damn about cellphones or radios. It’s laughable to hear the term “military grade explosive” when people want it to sound like something bigger and badder. When it comes to explosives the military will give up power to get stability. The military doesn’t use electrical igniters for that reason. Either shock tube or timed fuses. No danger of a radio accidentally setting off a charge.
Claymore blasting caps are electric. In urban areas, when you blast open a door or barricade, you need to use an electric initiation because you need exact timing (set it off right after the assault team is all lined up in position). I would assume this applies to countless other military uses of explosives. I would also assume there must be some kind of standard issue remote detonator you can use if you want to rig something to blow on a radio signal.
No we use shocktube to blow doors. Ive done many dozen of breeches either personally or as a supervisor. I’ve never even seen an electrical firing system for any of our explosives. They aren’t even an option to get from the ammo supply point. Combat Engineers are not trained to use them. Somewhere in the Corps of Engineers they may be used for construction purposes (most likely by contractors) but the are certainly not used in combat operation.
BTW in the current combat environment the enemy often uses radio/phone controlled detonation. We have multiple systems that defeat all such signals. That would make it difficult to set anything off ourselves using the same types of systems. Shock tube is safe, reliable, and stable. Stable is what you want when your explosives are being carried in you ruck or tossed down from the back of a truck.
When I was young, many years ago, you needed around 500mA at 500mV.
You actually used much higher voltages and currents, but you were a long way away, there were long thin wires, multiple detonators on the wires, and you wanted to be sure they all went off.
Incidentally, 500mA at 500mV is well within the range of an ordinary Taser. They ordinarily quote the average current out of those things, which is much smaller, because it is only pulsed. But the energy and current in each pulse is plenty to detonate a 500mA/500mV detonaror. – you don’t get people temporarily incapacited by touching the anttenna of a CB radio, which, if you were unlucky, could detonate an electric cap.
Modern caps are certainly designed to be immune to static electricity, and safety caps take a lot more energy to start.