Table of Contents

10.6.2 Dual Power Supply

It is essential that electrical power to tunnels be continuously available for ventilation, emergency egress and other safety reasons. Two sources of supply from a power company are preferred, each rated to supply the full load of the tunnel electrical system with an automatic transfer system to enable selection of the available supply. During operation, both could be running at 50% capacity, and on the failure of one, the other would automatically provide 100% power output.