Electrical Panel Sizing: Plan for Current & Future Loads

Requirements:

• List all permanent and occasional appliances and estimate their kW (heating, cooker, oven, EV charger, heat pump, major appliances).
• Apply a sensible diversity factor for groups of appliances (use conservative diversity for new installations).
• Convert total kW to amps at the supply voltage to size main incomer and service fuse (I = P / V for single-phase, I per phase for three-phase).
• Include a future-proof allowance (recommend at least 20–40% extra capacity for foreseeable additions).

Requirements:

• Choose single-phase for typical small homes with modest loads; prefer three-phase when continuous or future loads exceed typical single-phase supply (~10–16 kW depending on local supply limits).
• If planning EV charging, heat pump, or multiple large appliances, select three-phase to allow load balancing and smaller per-phase currents.
• Design to allow phase balancing and future redistribution of circuits across phases.

Requirements:

• Reserve extra ways/modules in the consumer unit — aim for several spare circuit positions (typical recommendation: at least 2–6 spare ways depending on home size).
• Provide spare current capacity on the main incomer (implement the 20–40% headroom rule) to avoid full replacement when adding EV charger or heat pump.
• Allow physical space and conduit/cable routes for future metering, EV circuit, and PV/inverter connections.

Requirements:

• Use appropriately rated miniature circuit breakers (MCBs) and residual current devices (RCDs) or RCBOs to protect circuits and people.
• Group circuits logically (e.g., lighting, sockets, heating, EV) and provide selective coordination where needed to avoid unnecessary total shutdowns.
• Fit surge protection devices where PV, EV chargers or sensitive electronics are present.
• Ensure earthing and equipotential bonding meet local requirements.

Requirements:

• Plan space for generation/charger interfaces: AC isolators, generation meters, and smart export/import meters as required.
• Ensure inverter anti-islanding and export limits meet the local grid operator rules before commissioning.
• Provide clear labeling of generation, export meter, and dedicated EV circuit for later inspection and maintenance.

Requirements:

• Install the panel at an accessible height with required clearances and an appropriate IP rating for the location.
• Label all circuits clearly, keep an up-to-date circuit schedule, and record changes for future owners/maintenance.
• Engage a qualified electrician for final design, verification, and sign-off; obtain any required inspections or certificates.