In our distribution system we used to have a lot of 6.9kv delta.
Which on a single-phase line, you had 2 phases on the crossarm. These lines have been cutover to 7.2kv wye, with one of the old phases being made the neutral. When this was done the insulator on the phase was changed out to a larger insulator , and the neutral kept the old brown insulator, so it could be easily identified.
Everyone is taught not to trust this, but sometimes it is taken for granted. My crew had a job to change out a rotten pole outside city limits. It was in the mountains with no transformers close by. The terrain was rocky, so my Foreman decided to pull the old pole and set the new one in the same hole.
My job was to float the neutral and hold the phase in the bucket truck. I looked up and saw a new insulator on the phase, and old on the neutral. But I have taught the apprentices not to trust this, so I decided to practice what I preach. I took a tester up with me, and it turned out that the neutral was the phase. That could have been ugly as the phase would have been about 5 feet from ground, where the rest of the crew was setting the pole.
Always take the time to check things out; don't take anything for granted.
Be safe always!