What makes an electrical schematic a standard one?


Thread Starter


I've been working on electrical schematic design.
What are the basic requirements that makes a schematic complying to a standard, be it an IEC standard, JIC, JIS, AS or anything else.

I've to design electrical schematics in compliance with IEC standard.

I tried to know about the standards to make a electrical schematic, but i cudnt get any document. pls help by sharing any documents / links which you have


James Ingraham

The wonderful thing about standards is that there are so many to choose from...

IEC does not truly define what an electrical schematic should look like. There are some pre-defined things, like some symbols, and the fact that the positive rail goes on the top and negative on the bottom. (Or did I just get that backwards?)

Really, the best thing to do is look over some drawings with another designer explaining the main features. Unfortunately, I can't help you much. Most of us here in the U.S. don't do IEC.

-James Ingraham
Sage Autmation, Inc.
Hi James,

Thank you very much for your reply.

UK follows IEC... Can you please tell me what standards are being followed in US?
If this is to meet a customer specification, then I would suggest asking the customer for a sample of drawings that they happen to like and use those as a guide.

James Ingraham

Harder question than you might think.

The whole top-to-bottom vs. left-to-right thing on the power rails is generally called out by saying IEC vs. JIC. JIC doesn't actually exist any more. The main standards body in the US is the National Fire Protection Association (NFPA), which publishes the National Electrical Code (NEC). The NEC book is NFPA 70. In the industrial world we also need NFPA 79.

There is also the Underwriter's Laboratory (UL). UL is a bit on the weird side; almost all consumer products will have a UL stamp, but it's not actually a legal requirement. In the industrial world UL isn't as omnipresent, but it's generally a good idea to pay attention to UL even if you aren't officially building a UL panel.

I happen to work with robots, which means I have to follow ANSI/RIA R15.06-1999. That's the "American National Standards Institute," which worked in conjunction with the Robotic Industries Association for that spec. And of course, ANSI is tightly linked with ISO. In fact, there's an addition to that standard, ANSI/RIA/ISO 10218-1:2007.

If you're in petrochemical or aerospace or nuclear you'll have different standards to deal with.

-James Ingraham
Sage Automation, Inc.