Do I need an electrician if I have an instantaneous hot water unit installed outside? Comments Off on Do I need an electrician if I have an instantaneous hot water unit installed outside? 18 Jan 2016 Vote Up 0 Vote Down Answered Public Public Private Technical Anonymous asked January 18, 2016 Hi, Do I need an electrician if I have an instantaneous hot water unit installed outside? 1 answer Vote Up 0 Vote Down Public ⋅ January 19, 2016 Yes, the instantaneous hot water unit requires a 240V power supply. #1 Please login or Register to Submit Answer