G seems to be obviously (G)round, but I have no idea which of the others is Neutral and which is Hot.
North American Standard
W, White, Neutral
Z , Black, Hot (120Vac/60Hz)
G, Green, Earth Ground
NEMA 1-15P SPT-2(wire) 18-16/2C AWG
thanks to david
WJ-23-1 5-15P SJT/W 18-12/3C
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