RCD = Residual Current
An RCD provides much the same functionality as the GFCI (ground fault circuit interrupter), protecting against an imbalance of current
on the hot and neutral wires. If the current is not equal on both wires, some current is being lost
to ground (a ground fault), and the unit trips (opens) cct).
Originally Posted by CharlieJ
When working on supposedly "tagged and locked" circuits, something that you can never be sure of on any pleasure vessel, I keep my Fluke (or equivalent) contact voltage tester Fluke 1AC-II / 1LAC-II VoltAlert in front of me and use it to test the conductor or component that is "dead" before I touch it. This action occurs after I have initially tested the conductor or component with a Fluke electronic "Wiggins" Fluke T+PRO / T+ Voltage and Continuity Testers...
Indeed; just the sort of belt & suspenders approach to electrical safety
In addition to the performing the various & multiple "tests", it can't hurt to ground out any conductor, prior to tentatively touching it.
Those non-contact voltage testers (Cct. Alert, middle left) are great tools, but should only be trusted to indicate that a circuit is “live” - not that it’s safely “dead”.