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Arc blast - is is something for “normal” people to worry about?
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Dan123456:
I’ve been getting a lot of videos recommended to me lately on the dangers of arc flash / arc blast and it is some scary shit  :scared:

All of these have been accidents in industrial settings or test facilities with 1000’s or 10,000’s of amps so I would assume it isn’t something “normal” people (I.e. anyone just dealing with single phase mains or high amperage DC) need to worry about but researching it isn’t quite as clear as I would like.

The most black and white number was from good old Wikipedia stating “Most 400 V and above electrical services have sufficient capacity to cause an arc flash hazard.”

https://en.m.wikipedia.org/wiki/Arc_flash

Does that simply mean, so long as you aren’t dealing with 400V+, it isn’t something you need to worry about?

Or can it still occur at lower voltages such as normal 240V mains or with say an 800A 12V car battery (but obviously with less power compared to the super nasty industrial accident type situations)?
Someone:
Partly the voltage, more so the fault current, and actually the energy dissipated in a fault.

An automotive starting battery is already fairly dangerous, but not to the level of x00V with xxkA behind it (live working on CAT III/CAT IV). Remember those are the fault conditions, the nominal rating may be something benign like "just" 240V 20A.
bdunham7:
The actual arc-flash phenomenon (the one that blows you up, not the spark in a light bulb as it burns out) isn't an issue for single-phase mains of any voltage or for low-voltage DC systems regardless of fault current.  You still can have a pretty big spark or arc and lots of molten metal flying around--like welding--but you won't be vaporized or fly through the air.

Typically this is an issue for 3-phase service panels or large equipment of 480V and higher, but there were recent revisions to regulations requiring PPE and precautions to be taken even in certain 208 or 240VAC three-phase panels if they had a very high fault current. 

So no, you aren't going to be arc-flashed into a pile of ash while repairing your toaster or replacing your car battery.   

coppercone2:
people say that to mean nasty burn if they don't know the exact specifics and IMO I am happy that they at least know it can do something bad lol

usually to get a super severe burn from mains (not electiricution) you would need to have something like maybe wet gloves (steam burn) cupped around a short circuit (say pushing something in to a live board that requires alot of force and have that short out). like fucking with some kind of pump. Like those cotton gloves with the grippy dots that you might feel are the glove of choice for doing plumbing on a jacuzi pump.


But IDK that would happen if you have a circuit breaker malfunction. Because the maximum thermal energy is basically governed by the circuit breaker.
T3sl4co1l:
Residential circuits are usually on the order of a few kA fault current.  At 120V, it's not too bad; at 240V, I don't think it's something that will jump out at you, but it can cause extended damage to circuitry -- burned traces, pads, damaged nearby components as the ball of plasma sinks current into anything conductive nearby.

The main thing is when fault currents are high (industrial 240V+ circuits), and fusing isn't proper, allowing tons of energy let-through.  Then the plasma cloud can grow from some inches to some meters, and seriously propel things.

Tim
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