What happens when current flows through the earth? Does it trip?

[DanMcLiverpool]

Supposing I fit a metal light fitting, and I do a terrible job - and the live comes out from the terminal screw and hits the fitting, but it's well earthed - current will flow through the earth cable (hopefully) providing a circuit with less resistance than if I touch it.

When this is happens, does it just keep flowing until I notice something is wrong and cut the power etc.? Or does this cause a short and trip the RCD/something else immediately?

Context: I'm a DIY'er, I'm not qualified (you may have guessed!).

 

[littlespark]

It trips the breaker or blows the fuse.

Back in the power station, the earth and neutral are linked. Which means a live to earth short is the same as a live to neutral with no actual load involved. Ohms law states I = V/R
Or in English, current is voltage divided by resistance. A dead short is zero or very very small resistance, and your voltage is 230 in this country.

so we have I = 230/something close to zero
Divide anything by near zero, and you get very very high current. Enough to trip a 6A breaker

 

[DanMcLiverpool]

Thanks @littlespark! Appreciate the clear answer.