This would be a topic for another forum section, but as long as we're into it please bare with me.
What is the AFCI trip energy (amperage) of characteristic electrical arcing waveform?
Why are GFCI required in garages and hangers, but not on industrial floors such as an engine room?
Given a choice of 5mA or 20A device tripping currents it seems that with GFCI protection would provide an order of magnitude improvement. Especially with a lighter than air explosive gas.
I hope your using an explosion proof drop light, A GFCI still provides full circuit current through it on the hot and neutral, in no way does a GFCI reduce this nor can it, what do you think could happen if the air around the receptacle was at the right mixture to combust, and you happened to trip on the cord and pull it out of the receptacle, if the drop cord light is on, there will be a spark at the receptacle, also as was said, a dead short to ground will produce enough current to trip the branch circuit breaker, I have had it happen, GFCI's do not limit the fault current on a dead short, its not fast enough, and is design that way, there is a delay built in the IC chip, this is to help to prevent neusent tripping, As far as AFCI"S go, the info I have on them is they don't even start looking until 5 amps, and don't trip to as much as 75 amp signature is reached, after my pointing this out to UL back a few years ago it might have been lowered but I don't have this info.
