What is RDC?
A typo It is RCD. (Residual Current Detector)
This is what the rest of the world uses for GFCI type protection but
they are usually set for 30ma, not the 5 ma the US uses.
They are also typically in the main for the panel, not the branch
circuits.
This is a New Zealand panel. The blue handle is the RCD
So a fault would shut all power to your home? That's not good.