This electrical wiring lighting plan All three light sources are linked in series. Each lamp is connected to the next one, so the L (Line, also known as live or phase) is connected to the first lamp, and the other lights are connected via the middle wire and the last wire as N (Neutral), which is then connected to the supply voltage. According to the analogy of a series circuit, the flowing current is the same in these incandescent bulbs/lamps. Still, the voltage is different, unlike a parallel circuit, where the voltage is the same at each point where the current is different. One major disadvantage of a series lighting circuit is that adding or removing one lamp from the circuit will affect the overall circuit, i.e., the other lamps. Download EdrawMax and create useful lighting electrical plans today.