Euclid M&D
New User
- Location
- Colorado
- Occupation
- Engineer
Hi, I'm a machine shop owner preparing a new shop to move to. My current shop is on 208Y and I have NEMA 21-20 (120/208V 4 pole/5 wire) plugs for some of my smaller equipment that has 120V accessories in addition to 3 phase. I really like this setup with the neutral included for its versatility and not needing multiple wires running to a single machine. My new shop though is 240V delta and my electrician is telling me I can't use 21-20s because they're only rated for 208V. I understand how it's a little risky due to the presence of the high leg, but with diligent color coding it doesn't concern me too much. So I'm wondering if it's ever acceptable to use a 21-20 in this manner, or more importantly if it has any chance of passing inspections. Another option would be to use a NEMA 22-20 which is rated for 277/480V. That would solve rated voltage being too low, but isn't really the intention of that plug. It also doesn't solve the danger of frying 120V equipment with the wild leg which is probably the main reason plugs suppling neutral with delta is uncommon. Any thoughts? I'm guessing the only real solution is using a second cord to supply the 120V.
Thanks,
Alex
Thanks,
Alex
