wiring - Can I run wires from two separate circuits through the same box? - Home Improvement Stack Exchange
5 AMP 4 TERMINALS 4 X 1.5MM WHITE JUNCTION BOX LGK825 : Amazon.co.uk: DIY & Tools
IP44 Junction Box with Push on Lid and 15A 5 Way Strip Connector for Electrical Wiring and Lighting - Indoor or Outdoor - 65mm : Amazon.co.uk: DIY & Tools
5A Junction Box 4 Terminal Click WA075 5 Amp
Extending a lighting circuit - Step-by-step guide and video