TR, remind me to:
1. Put a red fink tag in your box for a MAJOR hookup violation.2. Sweep up what is left of you and pack it in a band aid box once that 880-3ph fries you and three other people to a crisp! Just the flash on that blow up woulf fry you and they'd hear the explosion clear across the site!
Here is the correct hookup if you want a delta. You take a grounded center tap from one leg of the transformer, which gives you higher P=P voltage and you can then run a synchronous single-phase step down to supply a 250 VAC single phase breaker panel.
Anyway, break out your NEC and FOLLOW THE RULES!
It ius a lot easier just to tap one leg of that 3-phase line, and run a step up/ or step down center tap transformer that will deliver you the current you will need. Always opt for the bigger transformer because you may need the reserve later. Here are four ways to hook up the same center-tap transformer.
I'll pass that hook-up.