Electrical current will always follow a path of least resistance and so notionally when a length of rail is considered the rail itself will always present a better conductor than the concrete or soil that sits beyond the insulation in embedded rail. Even conductive materials have performance tolerances in terms of their current carrying capacity and the way in which electricity is being introduced will also contribute to performance. The way that rail performs as a conductor is impacted on by the way in which the circuit is arranged. Generally in light rail systems positive charge powers the tram, carriage, or street car, but when it is breaking the running rails serve as a negative return circuit for the current to return to the substation. This “dumping” of electrical current is not dissimilar from a lightning strike in terms of a short duration surge. If one considers how a length gutter works with water it may be easier to understand. If water is steadily, but constantly, poured into a gutter it is likely that the trickle or flow will be easily handled by the pipe; however, if a bucket of water is thrown in all at once then inevitably an amount of it will spill over. As such in light rail systems it is inevitable in embedded rail that an amount of current may leave the rail, however keeping that within the tolerances of the construction specification is vital.