NEC Mandatory vs Optional Sections Question

[tmillard]

I did a quick search of the forum on this and did not find what I was looking for....

A few times in the past I have seen it noted that certain sections of the NEC were optional and not mandatory. For instance, section 645 regarding data centers, etc.

So I reviewed section 90.3 of the 2008 NEC, under 'Code Arrangement', and it notes that Chapters 1 through 4 apply to all electrical installations, and chapters 5 through 6 supplement chapters 1 through 4.

I don't interpret it as sections 5 through 6 being optional. Am I reading this right? I believe I would have a hard time justifying to someone that I don't have to comply with these sections.

Any thoughts?

Tom

 

[iwire]

I would say some Articles of 600 are more optional then others. :smile:

645 is great example, we never have to use 645 unless we want to take advantage of the less restrictive wiring methods it allows. Basically if you want to run a lot of rubber cord under the floor you will have to use 645, if you wire the place with the appropriate chapter 3 wiring method you can ignore article 645.

630 Welders is another good example. 630 allows us to do some strange things with over current protection and conductor sizing based on the welder. We can use large breakers with small conductors.

But we can choose to ignore 630 and wire the welder with full size conductors with over current protection sized normally.

 

[jim dungar]

I did a quick search of the forum on this and did not find what I was looking for....

A few times in the past I have seen it noted that certain sections of the NEC were optional and not mandatory. For instance, section 645 regarding data centers, etc.

So I reviewed section 90.3 of the 2008 NEC, under 'Code Arrangement', and it notes that Chapters 1 through 4 apply to all electrical installations, and chapters 5 through 6 supplement chapters 1 through 4.

I don't interpret it as sections 5 through 6 being optional. Am I reading this right? I believe I would have a hard time justifying to someone that I don't have to comply with these sections.

Sections 5 and 6 are not optional, they are just not universal. You must follow them if they are applicable to your facility.