Since you have a starter present, the breaker is only used for "overcurrent" protection.
"Overload" protection is provided by the "heaters" in the starter.
Now, let's look at your information...like Alan, I have some problems with your numbers.
The largest "heater" for a size ) starter will handle 18 amps- quite a bit less than what you say you have. A size 1 goes to 27 amps, and a size 2 up to 46 amps.
Since you say you measured 32 amps, and the nameplate is marked 28 amps, you need a size 2 starter.
Now, let's look at table 430.248 of the NEC. According to this table, a 5 Hp 230 v single phase motor has a full load current of 28 amps. This is the value used for selecting your wire; since the application precludes continuous operation, I am comfortable using 28 as the basis for selecting #10 as the wire- IF this is a 5 hp motor!!!
The "problem" is that table 430.248 typically shows a FLA much higher than what is on the motor nameplate....there should be no way a 5 hp motor would draw 32 amps. If you are drawing 32 amps, then you need a 7 1/2 hp motor, which in turn leads us to #8 as the wire size.
Now for sizing the circuit breaker and disconnect.
The disconnect must be rated to 115% of the 40 amps from the table, or 47 amps. The next size disconnect is rated 60 amps, so tha't what you need.
The circuit breaker can be as much as 250% of the 32 you measure...this comes to 80 amps, which is considered a standard breaker size.
(I'm sure you already knew most of this- I'm just being thorough for the others out there)
Table 430.33 allows you to size your wire based upon the nameplate FLA, rather than the NEC table, and sometimes might allow the use of a smaller wire. In your case, 28 x 1.5 = 42, so you'ld have to use #8 anyway.
In theory, you could use the breaker as your sole disconnect and overload protector- but that would make it "continuous," as circuit breakers have no contacts that allow the controls to operate.
If the pump is controlled by, say, a float....then you can consider it as intermittent. If someone is actually flipping a switch, then it's continuous. That's how I understand the issue here.
A note about horsepower ratings: these things are best ignored, as manufacturers have been lying about them for decades. The FLA on the nameplate is the "real" number. If you are exceeding that number, there is a problem somewhere, and the motor is being damaged. (Take the reading after the motor is up to speed, and not during the start-up period).
Selecting the appropriate heater will allow you to best protect the pump against over-heating.
That a size 0 starter is being used suggests to me that the heaters have been bypassed- or that the amp readings we have are way off.
