The simpilest way is a fuse or circuit breaker or a multipul outlet board with overload built in.
The principal reason for fuses and circuit breakers is to protect cables from gross overload, if you are plugging an extension chord into a cheep inverter and a short develops the inverters overload should take care of that, you may melt your chord, although it is unlikley that the average cheep inverter will have the grunt to melt a chord.
For a precise answer you must give precise information, that was Fabricators point.
Allan