Load break switch symbol
Also called Switch-disconnector, LBS, On-load isolating switch
A load break switch can open and close normal load current and also isolates, but cannot clear a fault. It is often combined with fuses.
What the load break switch symbol means
A load break switch can open and close normal load current and also isolates, but cannot clear a fault. It is often combined with fuses.
ANSI and IEC symbols
Where you see it
Ring main units, transformer feeders and medium voltage distribution.
What is written next to it
On a one-line, the load break switch carries its tag and its ratings: rated voltage and current, making capacity, and fuse ratings when fused.
What gets checked at commissioning
Before the load break switch is energised, the test records usually cover: contact resistance, operation and interlocks. Each check is recorded against the tag, so the system can be handed over with its evidence. See commissioning software.
Related symbols
Frequently asked questions
What does the load break switch symbol look like?
On ANSI drawings: Usually drawn as a disconnect switch and marked as load break in its label. In IEC 60617: A switch with both the disconnector bar and the switch-disconnector mark at the fixed contact.
Is the load break switch symbol the same in IEC and ANSI?
No. A switch with both the disconnector bar and the switch-disconnector mark at the fixed contact. The IEC 60617 number is S00290.
Where is a load break switch used?
Ring main units, transformer feeders and medium voltage distribution.
- In production since 2014
- Thousands of daily users
- On MODEC FPSO projects since 2016