Heat Pump Electrical Installation | Power Supply, Breakers, Cables

A heat pump is one of the most demanding appliances in a modern home. Proper heat pump power supply requires appropriate electrical installation planning before construction begins. This guide will help you avoid costly mistakes.

Heat Pump Electrical Requirements

Most heat pumps above 5kW require three-phase power (400V). Typical requirements:

• 4-8 kW: Single-phase (230V) or three-phase, C16-C20 breaker
• 8-12 kW: Three-phase (400V), C16-C20 breaker per phase
• 12-16 kW: Three-phase (400V), C20-C25 breaker per phase

Dedicated Circuit for Heat Pump

Heat pump electrical installation requires a separate, dedicated circuit. This means:

• Separate cable run directly from distribution board to heat pump
• Own overcurrent protection (C-type MCB)
• Own residual current device (Type A or B RCD)
• Isolator switch at the heat pump (required by many manufacturers)

Cable Size Selection

Cable cross-section depends on heat pump power and cable length:

• Up to 4 kW (single-phase): 3×2.5mm² (up to 25m) or 3×4mm² (longer runs)
• Up to 8 kW (three-phase): 5×2.5mm² (up to 20m) or 5×4mm² (longer runs)
• Up to 16 kW (three-phase): 5×4mm² or 5×6mm² (depending on length)

Why C-Characteristic Instead of B?

Heat pumps have compressors with motors that draw high starting current. That's why we use C-type (time-delayed) breakers, not B-type (fast):

• B-characteristic: Trips at 3-5× rated current - too sensitive for motors
• C-characteristic: Trips at 5-10× rated current - ideal for heat pumps

Residual Current Device (RCD)

For heat pumps, Type A or Type B RCDs are recommended:

• Type A: Standard choice, protects against AC and pulsating DC
• Type B: Recommended by some manufacturers, also protects against pure DC
• Sensitivity: Standard 30mA (shock protection)

Supply Capacity and Heat Pump

Before installing a heat pump, check your supply capacity. A 12kW heat pump may need 15-20A per phase during startup. If you have a limited supply (e.g., 25A/phase), ensure other circuits won't overload the installation simultaneously.

Checklist Before Heat Pump Installation

1. Check electrical requirements of your specific heat pump model
2. Ensure you have three-phase supply (if required)
3. Plan dedicated circuit from distribution board to heat pump location
4. Select appropriate cable size with margin
5. Allow space in distribution board for breakers (minimum 4 modules)
6. Consult with heat pump installer before completing electrical work

In Electro Planner, you can easily plan a heat pump circuit. The program automatically selects the appropriate breaker, RCD, and cable size based on device power. Generate complete documentation ready for the electrician.