short to earth 120 v ac breaker
why wont the breaker trip.


Firstly, remember that a 20A breaker won't be OK at 19.9999 Amps and suddenly trip at 20.0001 Amps. A 20A breaker might pass 30A¹ for several minutes¹ (or more). It is mainly designed to protect wiring in the walls that slowly heats up due to overcurrent.

Secondly, soil/dirt is not a great conductor, especially when dry. It may have a high resistance that limits the fault-current.



Copper has conductivity 58,500 mS/m, Aluminium 36,900 mS/m

So the reasons are one or more of


the current isn't high enough (measure it with a clamp meter) and
the current hasn't been running long enough or
the breaker is faulty (probably least likely)




¹ All numbers guesswork for illustrative purposes