determine legs in 3 phase

Crosspost much ?

Anyway, sometimes there is a difficulty with determining which phase is lea ding and which is lagging. For (example) a reciprocating compressor it does not matter if it uses reed valves. But other things, it might matter.

Many years ago my Father ran horizontal boring mills. Big uns. One machine he said first of all had s***ty coolant flow. What's more every once in a w hile the impeller of the centrifugal coolant pump would come unscrewed. The company lived with that problem for a long time until he got there and got sick of it.

He figured out that the pump was running backwards. Just switch any two wir es and it reverses the motor. Any two, doesn't matter which two as long as it is a delta configuration. There is no reason to use the Y configuration on a little shitcan motor like that.

For some reason the machine itself ran the right way. Go figure, I did not wire it.

Sure. And just in case you've scared the fire department, maybe here's how to tidy things up to standard per code:

"The high leg service conductor of a 4-wire, 3-phase, delta connected servi ce must be permanently marked orange or identified by other effective means [NEC Article 230-56], and must terminate according to the following: meter termination: ANSI requires termination on the C phase; panelboard and swit chboard termination on the B or center phase [NEC Article 384-3(f)]. "