L5 30 Wiring Diagram - This single-phase two-pole twist-lock 120 volts 30 amps receptacle is common for small and mid-sized generators. If you load it to 80% of its rated current as recommended, you can. This single-phase three-pole 4-prong 120/240V 20A locking socket is found in some low-power (typically under 4,000W) portable generators. Its pinout is similar to that of L14-30 except the notch in the ground hole is reversed. If you follow UL and NEC® 2014 80% loading guidelines, you can draw from this outlet up to 240x20x0.8= 3,840 VA..