The control panel is the nerve centre of any industrial automation system. It houses the PLC, power supplies, motor starters, safety relays, terminal blocks, and all the electrical components that make an automation system function. Designing and building a professional control panel requires knowledge of standards, best practices, and practical craftsmanship.
Applicable Standards
In the UK, control panels must comply with:
- BS EN 61439: Low-voltage switchgear and control gear assemblies
- BS EN 60204-1: Safety of machinery - Electrical equipment of machines
- BS 7671 (IET Wiring Regulations): Requirements for electrical installations
- CE/UKCA marking requirements for placing products on the UK market
Panel Layout Design
A well-designed panel layout improves installation, maintenance, and troubleshooting:
Power section (left or top):
- Main isolator at an accessible height
- Circuit breakers and fuses for branch circuits
- Power supply units (24V DC for PLC and instrumentation)
Control section (centre):
- PLC CPU and I/O modules
- Safety relays and controllers
- Communication modules and switches
Drive section (right or bottom):
- Variable frequency drives
- Soft starters
- Motor protection devices
Terminal section (bottom):
- Marshalling terminals for field wiring
- Clearly labelled with wire numbers matching the schematic
Thermal Management
Heat is the enemy of electronic components. Proper thermal management extends equipment life and prevents unexpected failures:
- Calculate total heat dissipation from all components in the panel
- Select appropriate cooling method: natural convection, forced ventilation with filtered fans, or air conditioning units
- Maintain clearances around heat-generating components (especially VFDs)
- Consider the ambient temperature of the installation environment
Wiring Best Practices
Professional wiring practices make panels easier to commission and maintain:
- Use wire ducting (trunking) to route cables neatly between components
- Separate power and signal cables to minimise electromagnetic interference
- Use ferrules on all wire ends for reliable connections
- Label every wire with unique identification matching the electrical schematic
- Maintain a consistent colour code: brown for L1, black for L2, grey for L3, blue for neutral, green/yellow for earth, red or orange for 24V DC
- Use DIN rails for mounting all components
Testing and Commissioning
Before energising a new control panel, perform these checks:
- Visual inspection for correct wiring, component mounting, and labelling
- Continuity testing to verify all connections match the schematic
- Insulation resistance testing (megger test) at 500V DC
- Earth continuity testing to confirm all exposed metalwork is properly earthed
- Functional testing of each circuit under controlled conditions
EDWartens UK training includes practical control panel building exercises where students design, wire, and commission real panels following UK standards and best practices.