SafeSide™ Combo unit. Combine two complementary technologies voltage indicators and voltage portals. Voltage indicator is the primary voltage testing instrument because it provides the hardwired connection to the voltage source as required by NFPA 70E 120.1(5). Voltage portal (and the non-contact voltage detector pen) becomes the testing device for the voltage indicator. Both devices can be checked before a LOTO procedure while the control panel is energized to ensure proper operation. The traditional method of validating the voltage indicator to an independent voltage source is met with the NCVD/voltage portal combination.