2P+E: two poles and earth
Line, neutral (or a second line) and earth. This is the single-phase family: 120 V yellow at 4h, 230 V blue at 6h, 277 V grey at 5h, 480 V red at 7h. The 320P6W to IEC 60320 C13 and C19 cords that feed rack PDUs are two-pole bodies. So is the 16 A blue plug on a European caravan or a marina pedestal.
3P+E: three poles and earth
Three lines and earth, no neutral. A delta-connected load, a three-phase motor, a welder, a chiller: anything that takes its power line-to-line only. 9h blue for 3Ø 250 V (the 208 V delta feeds common in North American data centres), 6h red for 380–415 V, 7h red for 480 V, 5h black for 600 V. The 12h orange body is the odd one: 125/250 V split phase, a North American single-phase system that happens to need three poles.
3P+N+E: three poles, neutral and earth
Three lines, a neutral and earth, for wye systems where single-phase loads hang off the three-phase feed. 9h blue for 3ØY 120/208 V (the North American rack PDU whip), 6h red for 230/400 V (the European industrial standard, 16, 32 and 63 A), 7h red for 277/480 V and 5h black for 347/600 V.
Reading the difference on a body
Count the sleeves. A 3P+N+E connector shows five, and the neutral is the same size as the lines while earth is larger. Codes make it faster: 420P9W is four wire, 520P9W five wire, same amperage, same hour, different system.
