Drawings / Electrical legend

Electrical symbol legend

Simplified one line shapes in the spirit of common IEC style teaching diagrams. Use them to talk with electricians about MCC buckets, lockout and PM scopes. Not for construction packages.

Draft teaching material marked until The Planner's Bench team signs off on technical accuracy. Symbols follow generally known public conventions (ISA style instrument bubbles, common mechanical and electrical one line shapes). Your site's drawing standards and procedures always govern.

One line symbols

Motor circuit bits planners care about

• MCC bucket: starter, fuses or breaker, control power and auxiliary contacts.
• Hand switch (HS): local or control room start stop.
• Run status: auxiliary contact to a light or DCS digital input.
• Overload: thermal or electronic protection that must be reset after a trip.

See the motor start stop example.

Grounding note

Equipment grounding and bonding are shown with the stacked ground bars. Planning electrical PM that opens a cabinet should include verifying ground connections are restored before re energizing. Site electrical procedures always govern.