Single Line Diagrams

Explain how single lines are connected to the site electrical safety program

The most important reason for keeping the single lines up to date is because it helps us protect each other by locking out the right equipment. The Single Line drawings provide the connecting information to the upstream power distribution system as well as determining the capacity and flash hazard for the downstream equipment. The flash hazard determines what PPE has to be worn to work on the buckets at the MCC. The single lines document the bus bracing for the particular MCC and allow us to know if equipment is over dutied. The accuracy of the single lines is audited for the Electrical KEA.

with a single line for an MCC, explain what each symbol is

Covered "Fed From", Incoming breaker (Frame & Trip), Horizontal Bus Ampacity, Combination Starter symbol (with frame, fuse size, starter size), extents of MCC, external wiring, wire labeling, field disconnects, motor HP, transformer size and configuration.

Source: Electrical Training Level 2 book, Tab 7

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