Busbar system, accessories Busbar center-to-center spacing 60 mm Busbar support 3-pole for TT profile consists of 2 busbar holders and 2 end covers 8US busbar system for setting up protective devices such as fuse switch disconnectors and circuit breakers – safe, space-saving and clearly laid out. The use of the 8US busbar systems from Siemens gives a number of options for installing rail-adaptable connecting, switching and installation devices. Cost-effective electrotechnical enhancement of modern distribution boards is possible due to their small footprint, compact design and quick assembly contacts. Mounting is on longitudinal stays and the rail gap is 60 mm. Key features of. to 1,600 A. www.siemens.com/switching-devices. Siemens offers a comprehensive portfolio of protection, switching, measuring and monitoring devices, distribution boards as well as switches and sockets for safe and efficient electrical infrastructure in buildings and industry.