How do I know if the module is working properly?

During installation you run through a self-test that checks whether each circuit is properly connected; you can repeat this later if you're in doubt. As long as a guest is present, you see consumption increase logically in relation to purchased credit, and the guest also sees this live on their phone. When the credit runs out, power cuts off except for the always-on circuit with fridge and wifi; if there's a fault in the module itself, nothing cuts off. Unusual consumption differences are usually due to guest behaviour, not the module.