Outdoor receptacles at a home need GFCI protection, 210.8(A)(4). 210.8 calls for a Class A GFCI.
UL 943 sets these limits: Class A GFCIs stay on below 4 mA and shut off at 6 mA or more. The Article 100 note repeats them. This one shuts off at 5 mA.
25 ms is a typical shut-off time at high current. Near the trip level it can take longer.
A GFCI needs no ground wire, so 406.12(D)(2)(b) lets a GFCI receptacle replace a two-prong one where there is no ground. The receptacle or its cover gets a "No Equipment Ground" label, and its ground screw is not connected on to outlets it feeds.
A GFCI can't stop a shock from hot to neutral. That current comes back on the neutral, so nothing is missing.
A tripped GFCI still has power on its line screws. Test before you touch (trade practice).
Tag the drill out until the plug is replaced (trade practice).
Shock effects are typical figures from OSHA, not code.
The panel is the service, so neutral and ground are bonded on its bar. They are kept apart everywhere past it.
Model: 120 V, 50 ft of 12 AWG copper on a 20 A breaker (Chapter 9, Table 8), 8 ft of 18 AWG cord, a 7 A drill, worn insulation of about 50 Ω from hot to case, earth return 25 Ω rod with the utility ground, skin 1 kΩ wet to 200 kΩ dry.
The worn spot is a poor-contact fault, so the breaker never sees enough to trip. A solid hot-to-case short with a ground pin would trip it.
Dots use a log scale so milliamps and amps both show. Red dots through the person are hidden under 1 mA. Cut open, not to scale.