A method of locating an internal arc in a gas-insulated line consisting of a succession of compartments CP i (i = 1, 2,..., N) filled with gas, the method being characterized in that, for each compartment CP i being surrounded by a current toroid TC i (i = 1, 2,..., N) through which there flows a current I i that is substantially identical from one compartment to another and being provided with at least one pressure sensor P i able to measure the pressure of the gas inside the compartment, the method comprises the following steps: reading, at a sampling frequency, the currents Ii that flow through the current toroids; calculating, at the sampling frequency, current differences I diff/i such that I diff/i = I i+1 - I i, and storing the calculated current differences; comparing the stored current differences I diff/i with a current threshold value and, as soon as a current difference is greater than or equal to the threshold value at a time t t: triggering a succession of pressure measurements by the pressure sensor P i, and storing the measured pressure values; calculating from the time variations of the stored pressure measurements a pressure rise time t m at which the pressure measured by the pressure sensor P i begins to increase; calculating a period Δt P that is the difference between the times t m and t t; calculating a time to that characterizes the occurrence of internal arcing in the compartment CP i from the time variations of the stored current differences; calculating a period Δt i that is the difference between the times t t and to; calculating a period Δt that is the sum of the previously-calculated periods Δt i and Δt P; and calculating the distance d that separates the pressure sensor Pi from the place at which the fault occurred using the equation d = V/Δt in which V is the speed of propagation of sound in the gas. reading, at a sampling frequency, the currents Ii that flow through the current toroids; calculating, at the sampling frequency, current differences I diff/i such that I diff/i = I i+1 - I i, and storing the calculated current differences; comparing the stored current differences I diff/i with a current threshold value and, as soon as a current difference is greater than or equal to the threshold value at a time t t: triggering a succession of pressure measurements by the pressure sensor P i, and storing the measured pressure values; calculating from the time variations of the stored pressure measurements a pressure rise time t m at which the pressure measured by the pressure sensor P i begins to increase; calculating a period Δt P that is the difference between the times t m and t t; calculating a time to that characterizes the occurrence of internal arcing in the compartment CP i from the time variations of the stored current differences; calculating a period Δt i that is the difference between the times t t and to; calculating a period Δt that is the sum of the previously-calculated periods Δt i and Δt P; and calculating the distance d that separates the pressure sensor Pi from the place at which the fault occurred using the equation d = V/Δt in which V is the speed of propagation of sound in the gas. triggering a succession of pressure measurements by the pressure sensor P i, and storing the measured pressure values; calculating from the time variations of the stored pressure measurements a pressure rise time t m at which the pressure measured by the pressure sensor P i begins to increase; calculating a period Δt P that is the difference between the times t m and t t; calculating a time to that characterizes the occurrence of internal arcing in the compartment CP i from the time variations of the stored current differences; calculating a period Δt i that is the difference between the times t t and to; calculating a period Δt that is the sum of the previously-calculated periods Δt i and Δt P; and calculating the distance d that separates the pressure sensor Pi from the place at which the fault occurred using the equation d = V/Δt in which V is the speed of propagation of sound in the gas.