How many units do I need for my fusebox?

One module per rental unit or charging point

In most cases, one module is sufficient per independent unit rented out to guests, and per charging point that is billed separately. Each unit receives its own QR code, its own rate, and its own billing, and that requires a module that measures the consumption of that unit precisely and, if necessary, disconnects it. For example, someone renting three separate vacation homes on one plot, each with its own electrical panel, installs three modules; someone renting one home with two charging points rented out separately counts those charging points as separate objects and reaches three modules in total in that example.

The situation becomes less clear-cut once multiple units are connected to one electrical panel with one main connection, or once the circuit groups in that panel are interspersed — for instance, when outlets from two guest accommodations are on the same circuit. In that case, the number of modules practically needed is determined not by the number of guests or objects, but by the way the circuit groups in the electrical panel are already organized. An inspection of the existing circuit breaker panel by the installing electrician will show whether the arrangement allows one module to be connected per unit, or whether the circuit groups must first be adjusted before that is possible.

What NEN 1010 says about circuit group distribution

The arrangement of an electrical panel into circuit groups, and the requirements those groups must meet, follow from NEN 1010, the standard for low-voltage installations that has legal status through the Building Decree. This standard does not determine how many modules are needed at an address — that follows from the number of rental objects and charging points — but rather how the underlying circuit breaker panel is constructed and may be modified, and thereby indirectly how many separate circuit groups are available to connect a module to. An installing electrician consults this standard when assessing or modifying the circuit group arrangement.