SWA 10BS Butt Splices. Specialised Wiring Accessories (SWA) is one of the UK's market leaders when it comes to manufacturing essential cable terminations, fixings, tools, and fastenings. With over 25 years' experience, SWA is a name associated with quality and reliability within the electrical industry. The SWA range of uninsulated, copper tube butt splices is manufactured from seamless copper tube to BS EN 12449:1999. Features of the range include: manufactured from 99.5% copper and fully annealed to ensure optimum ductility and prevent deformation such as cracking and splitting when crimping; internal barrel diameters suit standard cables as defined in BS 6360; terminals have the cable size identified on the splice, ensuring the selection of the correct tooling and dies. The SWA 10BS is a 10mm copper butt splice.