Pool Heater Tripping Circuit Breaker?

I have a pool heater that keeps tripping. There are two breakers on the same circuit, a 60 Amp outside and a 20 Amp inside, with 20 Amp ready wires. After calling the electrician back who installed the heater, he says there is nothing wrong with this practice. Another one says this is against code and not done. Any insight into this, or code/article I can use as proof of wrong-doings, or to show that this is OK? (p.s. the heater is still tripping)

Thanks!

By Chris W.