Electrical faults are best prevented by good design and the appropriate selection of system components coupled with careful installation-specific requirements of photovoltaic (PV) systems. PV arrays do not have a fixed voltage and current output, while they have the ability to produce and sustain electrical arcs with current values that are not significantly greater than normal operating ones. This chapter explores various installation designs to minimize or eliminate faults, including earthing arrangements and protection against lighting and overvoltage effects.