Hi Paul
My OHME charger charges at 7.4 kw. and in doing so in draws 30amp from the household system. You really ought to upgrade the house fuse to at least 80amp. Also the charger has a load compensator which monitors the load on the system, so if you have ,say, the cooker on, hob on and boiling a kettle the charger will automatically lower the load to itself until the load lowers.
Tony