Can you use 3 single pole 15 amp breakers with a common neutral in a 3 phase panel without a tie bar or common trip?

Yes, you can use three single-pole 15 amp breakers with a common neutral in a 3-phase panel, as long as the breakers are properly rated for the application and local electrical codes permit it. However, without a tie bar or common trip, these breakers will not trip simultaneously in the event of a fault, which could pose a safety risk. It's essential to ensure that the load is balanced across the three phases and that the neutral is adequately sized to handle the combined return current. Always consult a qualified electrician or local codes before making such installations.