LTB-32 and TB-32 are both terminal block accessories for MMS-32AF's. The LTB-32 can be used with a phase bus setup for connecting multiple MMS's to the same power source. 

The TB-32 cannot be used with a phase bus setup. The primary purpose of utilizing a TB-32 is to ensure the proper insulation distance between phases to meet the requirements of UL Combination Motor Controller Type E specs. TB-32 is only applicable to the MMS-32H and MMS-32HI.