Disconnect switch symbol
Also called Disconnector, Isolator, Device 89
A disconnect switch isolates a circuit so it can be worked on. It is only operated with no load current: it cannot interrupt load or fault current.
What the disconnect switch symbol means
A disconnect switch isolates a circuit so it can be worked on. It is only operated with no load current: it cannot interrupt load or fault current.
ANSI and IEC symbols
A switch blade between two contacts, sometimes marked 89, the ANSI number for a line switch.
ANSI SVGWhere you see it
On both sides of breakers, at transformer and line connections, and for visible isolation.
What is written next to it
On a one-line, the disconnect switch carries its tag and its ratings: rated voltage, rated current and short-time withstand current.
What gets checked at commissioning
Before the disconnect switch is energised, the test records usually cover: contact resistance, mechanical operation and interlocks with the breaker and earthing switch. Each check is recorded against the tag, so the system can be handed over with its evidence. See commissioning software.
ANSI device numbers
Protective functions you will often find with a disconnect switch:
- 89 line switch
See the full list of ANSI device numbers with their IEC equivalents.
Related symbols
Frequently asked questions
What does the disconnect switch symbol look like?
On ANSI drawings: A switch blade between two contacts, sometimes marked 89, the ANSI number for a line switch. In IEC 60617: A switch with a short bar across the fixed contact. The bar is the disconnector function, S00220.
Is the disconnect switch symbol the same in IEC and ANSI?
No. A switch with a short bar across the fixed contact. The bar is the disconnector function, S00220. The IEC 60617 number is S00288.
Where is a disconnect switch used?
On both sides of breakers, at transformer and line connections, and for visible isolation.
Which ANSI device numbers go with a disconnect switch?
89 line switch.
- In production since 2014
- Thousands of daily users
- On MODEC FPSO projects since 2016