Code language

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hhsting

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If nec 2017 says shall comply with a,b or c does that mean:

Choose one of the following from a,b,c

Or does it mean

One can do combination of a,b,c i.e.
a,b
b,c
a,c
Etc

Which one?
 
Language is fun.
Usually "Choose one of the following from a,b,c" means exactly that, choose one from the set.

On the other hand, "shall comply with a,b or c"* would mean the same, you much comply with at least one of the options, and if the options aren't exclusive or contradictory, complying with more than one is acceptable.
*IMHO not correctly punctuated, should be "a, b, or c"

One of the problems with "or" is that in common English it often means "this but not that"* whereas in logic it means "could be this, could be that, could be both"
*which is why people write the awful "and/or" construction
 
In logic, the condition "a or b or c" is interpreted as an inclusive or. It is satisfied by a, b, c, ab, ac, bc, and abc.
Another way of stating it is that you must satisfy at least one of the choices a, b, and c.
Sometimes the nature of a, b, and c is such that it is not possible to satisfy more than one of them at a time. But it would be the nature of the conditions, not the "or"
In ordinary language, a or b or c will be used in either the inclusive or exclusive (pick only one) sense.
To make it perfectly clear, you can say "at least one of a, b, and c" or "exactly one of a, b, and c."
"Or" by itself does not do the job in ordinary language.
But in logical analysis (foreign to the NEC) the meaning of the unqualified "or" is one or more from the choices.
In practice, if it is possible to satisfy more than one from a, b, and c, it is very unlikely that the Code intends for forbid satisfying more than one.

"Chose one of the following" is pretty clearly exclusive, but the Code never, as far as I know, never uses that language.
 
There are definitely times when there is a list of things that all must be complied with. One example that jumps to mind is the tap rules in 240.21. without looking at it, I think the wording is ...."complies with all of the following.…."
 
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