I've come across the following symbol, boxed in red, in a single line diagram for a switchboard. From looking at it, I'm interpreting it as some sort of ground connector, but I want to confirm.

Symbol in question

I have tried my best to search for it online but I've had no luck. I have tried the following and combinations of the following: ground connection ground symbols ground bus connection ground link ground disconnect electrical bus connection symbol

What is this symbol?

  • \$\begingroup\$ Try “grid arc suppression with 500 MCM cable. 3/0 size” \$\endgroup\$ Commented Jul 2, 2019 at 22:34
  • \$\begingroup\$ I wasn't able to find that symbol using any of those keywords. Found myself a few other new symbols though. \$\endgroup\$
    – user199402
    Commented Jul 3, 2019 at 2:49
  • \$\begingroup\$ OK I guess it is a non-std symbol. But definitely not a 3phase & Neutral short circuit to Ground Bus. but no kV is given. \$\endgroup\$ Commented Jul 3, 2019 at 2:53

2 Answers 2


Found it. I stumbled across the symbol in the first diagram while searching up TVSS schematics. I then decided to go really general with the search and found the second diagram using service entrance rated switchboard schematic.

It is a disconnect link or bonding jumper.

Diagram 1

TVSS Schematic

Source for Diagram 1 on this web page.

Diagram 2

Switchboard Schematic

Source for Diagram 2 on this web page.


from the context(circuit breaker switch), it looks like a thermal overload device symbol:


Also matches the wiki-provided symbol for "thermal fuse."


  • \$\begingroup\$ Does it make sense to have a thermal overload on the ground connection? Say there is a major fault to ground in the switchboard, what would happen if that line was disconnected? \$\endgroup\$
    – user199402
    Commented Jul 3, 2019 at 12:06
  • \$\begingroup\$ Jeff - Thanks for trying to help, but IMHO the symbols in the links you provide look different to the one highlighted in red in the original question, and therefore are not the answer to the question. :-( \$\endgroup\$
    – SamGibson
    Commented Jul 3, 2019 at 14:03

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