RCD safety switches come in a few different configurations, with standard RCDs protecting against electric shock by detecting current imbalance and switching off power, while RCBOs combine this protection with the overcurrent protection function of a standard circuit breaker in a single device. Understanding which type of device is installed in a specific workplace matters for how testing is approached, since the two device types, while related, aren't identical in function or in how they're checked. Newcastle Test and Tag identifies which type of safety switch protection is installed at a given workplace before testing, rather than assuming a single standard approach applies universally across every site. For workplaces unsure what type of safety switch protection they currently have installed, this is worth clarifying with an electrician or during an initial testing visit, since it affects both the testing approach and, more broadly, the overall protection a workplace's electrical system actually provides.