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Yet again, we are debating with colleagues to choose the correct power symbols in our schematics.

Some argue that using the horizontal 4-lines symbol for GND is a misunderstanding because this is not a real ground. Others say that only arrows are valid. On the 60617-2 snippet below, one can see that in French, the 02-15-01 symbol is named "Terre" (Earth) in french, but "Earth/Ground" in english. Thus, I am used to using this symbol when something is physically connected to the Earth.

So my question would be: is there an ISO/IEC standard about power symbols used in EDA, and which symbol is used to differentiate signal "GND" from power ground connected to Earth?

Here are some examples in my EDA software:

enter image description here

In ISO/IEC 60617-2:1996 I only found these references. It seems that all other symbols are not standard. Is that correct?

enter image description here

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  • \$\begingroup\$ You mean IEC 60617, it is used basically everywhere except in the US. Though similarities occur. \$\endgroup\$
    – Jeroen3
    Commented Apr 19, 2022 at 11:28
  • \$\begingroup\$ All of the ground symbols except the -3.3V are at least "de facto" industry standard. I would avoid to assign any special meaning other than general ground to the first ('T' upside-down), third (4 lines) or fifth (triangle). \$\endgroup\$
    – Lundin
    Commented Apr 19, 2022 at 12:48

2 Answers 2

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IEC 60617 (2007) The IEC 60617 snapshot taken in 2023

I’d like to add that the IEC 60617Frame/chassis” symbol had once been obsoleted in 2001, and has been revived and renamed to “Functional equipotential bonding.” Now it stands for more general things.


IEC 60417 does not contain schematic diagram symbols.

Note that the icons in IEC 60417 are irrelevant as for schematic drawings.

IEC 60417 (2015)

IEC explains:

IEC 60417 graphical symbols are primarily intended to:

  • identify the equipment or a part of the equipment (e.g. a control or display);
  • indicate a functional state (e.g. on, off, alarm);
  • designate connections (e.g. terminals, filling points for materials);
  • provide information on packaging (e.g. identification of contents, instructions for handling);
  • provide instruction for the operation of the equipment (e.g. limitations of use).

IEC 60417 does not apply to symbol originals for:

  • safety signs;
  • use on drawings and diagrams;
  • use in technical documentation of products and in technical product documentation;
  • use for public information.
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  • \$\begingroup\$ Welcome to Stack Exchange, Константин! If I'm interpreting this screenshot correctly, the IEC 60617 chassis symbol and the IEC 60417 chassis symbol look practically identical. Could you point out what's different between the two symbols? \$\endgroup\$ Commented Nov 1, 2023 at 5:11
  • \$\begingroup\$ @TannerSwett, the two standards serve different purposes. IEC 60417 contains “graphical symbols for use on equipment” or “icons,” and IEC 60617 contains “graphical symbols for use in electrotechnical diagrams,” that is, schematic circuit diagrams. \$\endgroup\$ Commented Nov 1, 2023 at 6:36
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Based on IEC 60617 you have 5 symbols (02-15-01 to 02-15-05) for ground reference.

  • enter image description here is referred to as "earth general symbol". A note says: supplementary information might be given if the status or purpose is not apparent.
  • enter image description here is frame or chassis, the hatching may be omitted, but then the line representing the frame must be thicker (looks like your leftmost symbol but with a thicker line at the bottom)
  • enter image description here is equipotentiality.

Then there are two variants of the earth symbol with circles:

  • full circle encloses earth symbol: protective earth
  • semicircle above earth: noiseless earth

Practice probably differs always a bit. I've seen the leftmost symbol used for the primary side reference point and the rightmost for secondary side reference point. Or the other way round.

The first symbol could be used in any way and I'd not interpret any special meaning into it, until the schematic shows me otherwise, but the close resemblance to protective earth makes me not use it on my own schematics.

I think only the frame and protective earth symbol have been used correctly in all the schematics I've seen...

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  • \$\begingroup\$ I am starting to understand the confusion. In french we have different words for "earth/terre" which is ground plane physically connected to the Earth, and "masse" which is the ground equipotential. Both are not the same because signal gnd isn't always connected to the Earth. If you look at the picture on the question, in french there is only "Terre", but on the english version you have "Ground/Earth". \$\endgroup\$
    – nowox
    Commented Apr 19, 2022 at 13:49
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    \$\begingroup\$ @nowox it's the same in German. \$\endgroup\$
    – Arsenal
    Commented Apr 20, 2022 at 7:40

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