I work at a steel plant and I've had to check power on a 3 phase system. When I measures the voltage it read 480 across 1-2, 2-3 and 1-3 leg which read 480 And is normal but when I read each leg to ground, two legs read 480 but the other leg read 0 volts?? Is this just a curtain type of delta or wye connection? Bc the way I always measure voltage I had power on all 3 legs to ground.

Could a 480 volt corner grounded delta system. This would produce the voltage readings you found.

Thanks your rights that's what it was.. I never seen a 3 phase system like that before...