Question about power connection

[Larry Korona]

Continuing work on upgrading my audio panel and intercom. Completed removal of the audio panel and intercom. I found a curious thing when I traced the power wire for the intercom. It had a circuit breaker installed directly next to the intercom box then it had a fuse in line then it appeared to be connected to the power side of another circuit breaker on the main bus. Is it an approved method to do this, connect on the power side the bus?

 

[Bell206]

Is it an approved method to do this, connect on the power side the bus?

No. But it can be common when equipment is replaced and the installer doesn't bother to chase the wires and simply adds onto an existing system. Fixing old work never seems to be a priority when installing avionics for some reason. Regardless, it needs to be corrected using only one circuit protection device per wire. AC43.13-1B has good guidance on this.