Remote Control Circuit Breakers are used for heavier power load control. RCCB's are usually located in the power distribution area of most aircraft. They provide the crew the ability to isolate a circuit "remotely". They can be used for A/C or D/C control.
Power for RCCB functionality is obtained from the input source that is to be controlled. It is normally tapped off of "B' and "C" phases in the case of a A/C unit.
The control of the unit is accomplished by the use of "grounds". One directly hooked to terminal block pin 5A. The other ground, on pin 3 ...... comes through a 1/2 amp circuit breaker located in the cockpit. With either ground missing, the RCCB will "not" close. Flight crews and maintenance can control large amperage loads by simply pulling a small breaker.
Troubleshooting a suspected RCCB fault is quite simple. Is there proper input voltage? Is there a hard ground on pin 3? Is there a ground on pin 5A? A "no" to any of these questions pretty much rules out the RCCB itself.
The control pins are removed from the terminal block with the white end of a red/white plastic removal/insertion tool. The RCCB has a small window on the top. If it's green, the unit is open. Red, it's closed.
One final note: a RCCB 1/2 amp control breaker should never "pop". There is no voltage on them...... Never say never though......
A useful explanation from EATON can be found below.