P3RA-060K heater trips breaker after 10-15 minutes

[scottd]

I have a 5 year old Intertherm P3RA-060K that works great for 10-15 minutes then it trips the breaker on the unit. The breaker in the house does not trip just the one on the unti. The A/C will run just fine, only the heater side breaker blows. I swapped the breakers (which are the same) and the one wired to the heater trips the same. I checked for loose / bad connections etc and everything looks great.

Thanks in advance

[flcruising]

Did you trace the wiring to the heating elements?