On Tue, 10 Sep 2019 14:40:44 -0500, Mark Lloyd
wrote:

On 9/9/19 4:33 PM, Clare Snyder wrote:

[snip]

When derived from 2 phases of a 3 phase supply you get 120 and 208
(the sum of 120 degree out of phase)

I'm not sure if it's the way you're supposed to figure it, but

240 * sin(120)

is approximately 208. I haven't seen it, but have heard of large
apartment buildings wired that way.
You got it correct. Step to the head of this class.