Have a simple UPS system with no Solar : Multiplus II with an ET112 on main incoming just after the Municipal meter - no CT clamp. I realise that ET112 is a slow reactor and that it all averages out but why when there is little load on the system (not charging - no non-critical loads) , does the Grid meter consistanly read 40W to100W lower than than the critical loads - I would have expected the reverse as the Multiplus must use some power - what am I missing?