The design here is for an enclosure for an ACS712 power sensor.

The ACS712 is a Fully Integrated, Hall-Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor.

These are in turn used as the center piece for current sensors that are popular to measure current connected to Arduinos or Raspberry Pis.They are available from a wide range of suppliers in different current measuring ranges (the most common being 5A, 20A and 30A.

The two piece enclosure here allows for the sensor to sit in the base and for the attaching wires from the supply being measured to be secured using a strap-tie. The header pins are still accessible thus isolating the part with the higher current flow from the low voltage points. The lid will snap into place over the top

Be aware: Each country will have its own regulations on what level of electrical equipment can be connected and adjusted by a home user. If you are in any doubt, ask a professional.