On 8/8/2018 1:43 PM, trader_4 wrote:
I've described it quite clearly before. Take your scope, hook the
scope ground to the neutral, which after all is the SYSTEM reference
point, by design, not some random, bizarre point I picked. Put
one probe on one hot, put one probe on the other hot. You'll see
two 120V sine waves, 180 deg out of phase with each other.

The transformer secondary winding has two ends, L1 and L2.Â* Put your scope common lead on L1.Â* Attach one trace probe to the secondary tap and the other trace probe to L2.

Your scope should display two traces in perfect sync that vary only in amplitude.Â* Pure single phase.