I happened to look in the AAC Textbook Lessons - Electric Circuits and E-Book and could not find any reference in the illustration of supply common symbols, i.e. Chassis, Earth, Logic -both Analog and Digital.?
Also the conductor wire colour standard appear to cover Power wiring, but I could find no reference to control wiring colour standard as outlined in NFPA79 etc? Being an electronic site, I would have thought the latter would have taken preference?

Also another observation is the Electrical industry tends to comply with the marking for Earth Ground using the International industrial standards symbol. But there appears a certain segement in the electronics community that insist on using earth ground for just about any power supply common, instead of the other accepted symbols.
This can make for some confusion when it is used without any regard as to whether the circuit is actually intended to be connected to earth.


Max.

 

Old habits are hard to die.

 

Old habits include negligent documentation of the various ground symbols.

A single horizontal line representing ground?
Triangle symbols without a number in them?
That's why we get paid...to figure out what the designer meant by reading a document that has a dozen, "Where does this really go?" in it.

 

Eagle 7.1 offers these choices:


Since one is frequently not sure of which convention is being followed, why not just label accordingly, when it matters?

John

 

Old habits include negligent documentation of the various ground symbols.
.

The basic ones are pretty well established?

A single horizontal line representing ground?
.

I personally have no problem with that it is usually clear as a power supply common, if there are more than one common it is usually indicated in some fashion by whoever draws up the schematic.

Triangle symbols without a number in them?
That's why we get paid...to figure out what the designer meant by reading a document that has a dozen, "Where does this really go?" in it.

That points to the ineptitude of the originator of the schematic, not that there is not enough symbol definitions in order to make it clear.
The problem is that apart from a few responsible sites and publications there are many that either do not conform to a published standard and guide or are oblivious they are causing confusion.
One such publication by Horowitz and Hill that is considered a sort of Bible by some, commit the practice all the way through the book and do not even have an index of schematic symbols.
Max.

 

That points to the ineptitude of the originator of the schematic.

Exactly!

 

True then, true now.

 

Both N.A. and IEC have standards which are close to each other, N.A. has NFPA79 which is based on the NEC.
I have worked with Industrial Electrical prints supplied by architectural companies, Part Production drawings, and machine drawings supplied by some of the major CNC control manuf such as Mitsubishi and Fanuc, and found all of them conform to a standard which can be read by anyone versed in the particular application of them, it seems it is only in the electronic design area where standards seem to go out the window, as I mentioned in the O.P.

This guy sums it up.

Max.