Questions about Numbers in NEC

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00crashtest

Senior Member
Location
California
Occupation
electrician trainee
In the 2020 Edition of the National Electric Code, 110.26(3) says that the clear height of the working space shall be at least "2.0 m (6 1/2 ft) or the height of the equipment, whichever is greater." Even though 2.0 m (which is 6.56168 ft) is not exactly equal to 6 1/2 ft (which is 1.9812 m), that is not a problem because 90.9(D) says, "Compliance with the numbers shown in either the SI system or the inch-pound system shall constitute compliance with this Code." So, either are equally accepted for compliance purposes of the NEC.

However, why is it "2.0" rather than just "2"? Is it for clarity reasons by just showing that 1.501 rounded up to 2 is not acceptable for this Code, is it to indicate significant figures like in measured values in hard science, or is it something else? For example, when assuming that the equipment is shorter, is a clear working height of 1.97 m, which is shorter than both of the values mentioned by the Code, complaint with the Code?
 

00crashtest

Senior Member
Location
California
Occupation
electrician trainee

00crashtest

Senior Member
Location
California
Occupation
electrician trainee
Oh no! I just found out, "Any opinion expressed, therefore, is the personal opinion of the responder and does not necessarily represent the official position of the NFPA or its Technical Committees." So, I would still appreciate your response here.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Yay! I finally found the link where I can submit questions directly to the authors of the NEC! :)
You have to be a member though. Which costs money. And as you noticed, the answer doesn't really mean anything.
 

gene6

Senior Member
Location
NY
Occupation
Electrician
However, why is it "2.0" rather than just "2"? Is it for clarity reasons by just showing that 1.501 rounded up to 2 is not acceptable for this Code, is it to indicate significant figures like in measured values in hard science, or is it something else?
Pro tip #1 stay friends with your AHJ.
Pro tip #2 nobody on the civilian side of things in the US that I know of does construction in metric so don't even go play that game, just stick to imperial units.
If your one of the few whom work to US codes/standards abroad thank you for your service and by all means use metric, by all means do use those metric units.
 
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