I'm curious how much current it is safe to pass through a 0.1" pitch pin header. I'm sure it will depend on the gauge and stranding of the wire attached to it as well, but assuming that is not the limiting factor how much could be safely passed?
Samtecs TSW standard 0.1" header has a variable voltage and current rating based on the matching connector it plugs into. This is due to how much surface area makes contact with the header. That says, it averages 4 to 6 amps per pin.
Based on the common design and material, most headers will have similar properties.
When used for stacking, as in two boards soldered to the same header, the max amperage is 3 amps @ 80 degrees C (I'm assuming per pin). Except for some of their dedicated power strips which have 8+ amp.