Understand the difference.

Compare the meaning, drawing context and source references of two entries. A similar graphic or shared abbreviation does not establish equivalence.

RMU

GA objects

Ring main unit

A ring main unit is a compact secondary-distribution switchgear assembly with a manufacturer-defined combination of switching functions. Its electrical configuration and physical envelope depend on the chosen product, rather than on the abbreviation RMU alone.

Drawing use

GA

Application

Power distribution

Reference family

Manufacturer

A distinction that matters

RMU does not specify one universal technology, dimension or combination of breaker, switch and fused ways.

Full referenceAdd to legend

Isolator

Symbols

Disconnector

A disconnector, often called an isolator, provides an isolation function in an electrical circuit. Its representation should be read with the drawing legend and the selected device specification. Do not infer load-breaking or fault-interruption capability simply because a drawing contains a switch-like mark.

Drawing use

SLD / Schematic

Application

Power distribution

Reference family

IEC / IEEE / ANSI

A distinction that matters

A load-break switch has a specified load-switching capability. A disconnector designation alone does not establish that capability.

Full referenceAdd to legend

Original educational previews. Follow the source references on each full entry for the appropriate standard or selected product.