symbology of drawings

[abojorge]

good morning people

There is some rule that requires how to make electrical drawings,

 

[petersonra]

good morning people

There is some rule that requires how to make electrical drawings,

There is no code I am aware of that specify symbols for electrical drawings. There are several standards have various symbols for different kinds of electrical drawings.

 

[retirede]

Back in the day when I made drawings, we used symbols as defined by JIC (Joint Industrial Council).

 

[junkhound]

good morning people

There is some rule that requires how to make electrical drawings,

The customer usually defines the symbol standard to use in their statement of work - outside of that whatever suits you. I typically use the symbols in Orcad PSpice as it is my most used tool.

wiki list
IEC 60617 (also known as British Standard BS 3939).
ANSI Y32.2-1975 (also known as IEEE Std 315-1975 or CSA Z99-1975)
IEEE Std 91/91a: graphic symbols for logic functions (used in digital electronics). It is referenced in ANSI Y32.2/IEEE Std 315.
Australian Standard AS 1102.

NASA, most aerospace companies, Orcad PSpice, Lin tech LTSpice, Mentor graphics, etc all have standards for symbols, many have slight variations. Army, Navy, USAF all have had variations of the standards.

One line diagrams have other standard symbols.

The customer usually defines the symbol standard to use in their statement of work - outside of that whatever suits you.

From some work with Russioan power supplies, they hav their own slightly different conventions also.

 

[Sahib]

There is no code I am aware of that specify symbols for electrical drawings. There are several standards have various symbols for different kinds of electrical drawings.

Interestingly, the Indian Electrical code mentions electrical symbols to be used by referring to various Indian standards.

 

[Besoeker]

Interestingly, the Indian Electrical code mentions electrical symbols to be used by referring to various Indian standards.

The International Electrotechnical Commission, IEC as most people know it, has standard electrical symbols.

 

[Sahib]

The International Electrotechnical Commission, IEC as most people know it, has standard electrical symbols.

It was already mentioned in post #4.

 

[Besoeker]

It was already mentioned in post #4.

Just checking to see if you were paying attention..........

 

[gadfly56]

Some day people doing fire alarm (I'm talking to you, architects) will discover NFPA 170 for all your fire protection symbology needs.

 

[petersonra]

Back in the day when I made drawings, we used symbols as defined by JIC (Joint Industrial Council).

JIC died in the 80s. It was eventually more or less replaced by NFPA79, although it lived on in some big companies that issued new standards very similar to JIC for a couple decades.

 

[retirede]

JIC died in the 80s. It was eventually more or less replaced by NFPA79, although it lived on in some big companies that issued new standards very similar to JIC for a couple decades.

That should give you an idea of what I mean when I say “back in the day”.

 

[petersonra]

That should give you an idea of what I mean when I say “back in the day”.

JIC seemed to just disappear. Someone told me one time that they couldn't get people to serve on any of the committees so even though the organization still existed it was effectively defunct after the late seventies. There is probably a good story there.

I also heard once that it never even officially dissolved. It just kind of disintegrated.

 

[Jraef]

JIC seemed to just disappear. Someone told me one time that they couldn't get people to serve on any of the committees so even though the organization still existed it was effectively defunct after the late seventies. There is probably a good story there.

I also heard once that it never even officially dissolved. It just kind of disintegrated.

If you read the preamble of NFPA 79, it provides a history that includes the incorporation of JIC standards and why.

But unfortunately NFPA doesn’t incorporate a standard for symbols as JIC once did, so most large companies simply keep referring to the JIC symbol library. The problem is, with nobody remaining to maintain and update them, changes in the industry, the advent of CAD and new devices that need to be depicted in drawings have not been kept up with. For that reason, we now have a de-facto mixture of old JIC with some newer devices defaulting to IEC symbology standards, or worse yet, people making up their own symbols. Considerate EEs will add a legend to a set of drawings, but that often doesn’t get printed out and passed on to those that need it in the field. It’s been a thorn in my side for years.

 

[petersonra]

If you read the preamble of NFPA 79, it provides a history that includes the incorporation of JIC standards and why.

But unfortunately NFPA doesn’t incorporate a standard for symbols as JIC once did, so most large companies simply keep referring to the JIC symbol library. The problem is, with nobody remaining to maintain and update them, changes in the industry, the advent of CAD and new devices that need to be depicted in drawings have not been kept up with. For that reason, we now have a de-facto mixture of old JIC with some newer devices defaulting to IEC symbology standards, or worse yet, people making up their own symbols. Considerate EEs will add a legend to a set of drawings, but that often doesn’t get printed out and passed on to those that need it in the field. It’s been a thorn in my side for years.

I don't recall ever seeing a preamble to NFPA79.

Every version of NFPA79 has at least some symbols shown in an annex with a reference to where they came from - an IEEE or ANSI standard I think. They also show the equivalent IEC symbol. It is not comprehensive though.

 

[Jraef]

I don't recall ever seeing a preamble to NFPA79.

Every version of NFPA79 has at least some symbols shown in an annex with a reference to where they came from - an IEEE or ANSI standard I think. They also show the equivalent IEC symbol. It is not comprehensive though.

You're right, the symbols are in there. I guess I had never scrolled down into the Annexes...

What I'm calling the preamble starts on page 79-1, "Origin and Development of NFPA 79"

On page 79-2:

In June 1981, the Joint Industrial Council (JIC) Board of Directors acknowledged the dated state of the electrical
and electronic standards and requested that NFPA 79 incorporate into its standard the material and topics covered by
the JIC electrical (EMP-1-67, EGP-1-67) and electronic (EL-1-71) standards with the intention that the JIC standards
eventually would be declared superseded. The NFPA Standards Council approved the request with the stipulation that
the material and topics incorporated from the JIC standards be limited to areas related to electrical shock and fire
hazards. The 1985 edition reflected the incorporation of the appropriate material from the JIC electrical (EMP-1-67,
EGP-1-67) standards not previously covered. The 1991, 1994, and 1997 editions include additional references to
international standards and reflect the committee’s efforts in harmonization.