MDAs are designed and manufactured in accordance with BS EN 61439-4 and key elements of the designs have been independently type tested, including bus bar systems, lifting arrangements, corrosion resistance, shock and vibration withstand, etc. Order this product from HSE Books It explains what to do to reduce the risk of accidents involving. These guidelines provide you with information on the installation of electricity mains, services, streetlamps, and other parts of our electricity networks. The guidelines also cover the safety aspects of GTC completing works onsite and specify your responsibilities in the delivery of the. B series Mains Distribution Assemblies for Construction Sites (MDAs) have been developed over the past 30 years and used on the majority of major UK construction projects in that period, including Heysham, Torness and Sizewell Nuclear Power Stations in the 1970s and 1980s, the Channel Tunnel and. This Electricity Specification provides information on various aspects of the approved designs for distribution substations and transforming points operated by Electricity North West Limited, hereinafter referred to as Electricity North West. Where a distribution substation or transforming point. to install, or they will be brought along on the day. Please ensure that you can provide a suitable storage area for all materials as you could be liable for a these are stored in a suitable location and kept dry. This guidance explains what to.