My truck battery is 12VDC -- it throws arcs to beat the band.
DC arc welders use 24-36VDC -- depending -- so you can't assume that a 24VDC system can't spark.
You're just assuming that there is no battery back-up in the system -- and that the power supply is feeble. Even so, they can STILL spark.
In an explosive atmosphere - it just takes the one spark.
Virtually all fire alarm circuits will have battery back-up.
ANY critical control circuit is going to have battery back-up -- usually a serious lead-acid gell battery.
The mere selection of 12VDC or 24VDC ( instead of 24VAC ) makes one assume that the control circuit has a battery back-up.
It's kaboom every time. I've seen battery tops blown of by sparking jumper cables -- all at 14VDC.
Intrinsically safe circuits stay below 3VDC, not 24VDC.
