What does N S T G stand for as power receptacles for electrical schematics? I believe A, B, C, D is more commonly used in the US, and I imagine it is arbitrary, but N S T G appears too random to be arbitrary. The G is fairly obvious: ground. But what about the N S T?

I think I read somewhere earlier it was a European nomenclature. I did a Google search but didn't find much...

 

N = Neutral
S, T = Phase or Line legs
G = Ground

R, S, T is comonly used as the input phases and U, V, W for the output phases of motor controllers, VFD's, and other industrial type systems.

Look at the color of the screws or terminals of your receptacle or plug. Green screws is for the ground connection, silver or white is for the Neutral connections, and brass or gold (sometimes black) is for the line voltage connections.