Medium Voltage Joints New Generation MIRP up 15kV The unique patented WT Henley Moulded Insulation Resin Protected Joint, has been developed over the years to become perhaps the simplest to install and the most reliable medium voltage cable jointing system available today. Suiting all cable configurations from Paper to Polymeric as well as Transition Jointing. Specified and trusted by many UK Electricity Companies, we can supply kits to suit all jointing requirements.