ring main
noun
Brit. <英>
1
- an electrical supply serving a series of consumers and returning to the original source, so that each consumer has an alternative path in the event of a failure（供电系统的）环形干线, 环形主线。
1.1
- another term for RING CIRCUIT.
2
- an arrangement of pipes forming a closed loop into which steam, water, or sewage may be fed and whose points of draw-off are supplied by flow from two directions环形管道系统。