NFPA 79 allowed wire size

[jimmalik]

I have worked at several companies and everyone has a different interpetation of the NFPA 79 code for wire size in control box and on machine wiring. My current company is using 20AWG inside the box from PLC to terminal blocks. And use 24AWG cable from box to descrete devices(sensors, etc).
I am talking about DC. I have always used 18AWG. NFPA 79 has too many exceptions, etc. Why can't they make the code cut and dry. Can someone clarify this as to code and not personal/company preference.

Jim

 

[DonPhillips]

I will have to say, I think what you are experiencing is the result of the consensus code change process of NFPA. Industry has great influence on what is published in these codes.

Some code orgaqnizations only allow governmental members to vote on changes. Theoretically, their only interest is in public safety.

Don Phillips

http://worthingtonengineering.com