I came across this symbol in an IEC standard and don't know exactly what it means. From the circuit is appears to be a generic load, but does it have any other significance?

IEC 60079 Part 11 Figure A.4


1 Answer 1


That looks like a gas discharge tube. These are used for over voltage protection. Gas filled tubes dissipate large voltage transients making them suitable for lightning protection applications such as in telecom circuits.

The symbol is similar to one that is used for a TVS diode which is also used for similar purposes.

  • \$\begingroup\$ It does look similar to a TVS diode, but I don't think that makes sense considering its position in the circuit. \$\endgroup\$
    – JonathanN
    Commented Mar 30, 2017 at 10:22
  • \$\begingroup\$ True. They are usually placed right across the supply. My point was to simply point out the similarities in the way the symbol looked since you had asked about that. \$\endgroup\$ Commented Mar 30, 2017 at 15:03
  • \$\begingroup\$ Another nane would be fluorescent tube. \$\endgroup\$
    – winny
    Commented Jun 9, 2017 at 18:32

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