I have installed 120v manual motor starters forever.
Also install magnetic 3 phase motor starters forever

I recently bought a 230v motor for a pump for the deerlease and
wanted to install a manual motor starter for it. I sized the overloads
according to the nameplate and Sf etc etc.

But what got me was that the manual motor starter only takes out one
leg of the 230v when it trips on overload.

I think this is a bad thing.
Although the motor wont work on one leg of 115v
Why would anyone engineer it that way?

I thought it was code that you had to open ALL legs to motor when it
trip on overload.

If you have a 3 phase motor on a magnetic there are 3 sets of
overloads that will trip the system.
Any of them that will take out all 3 phases