You're very close! Let's clarify

Fraction Thereof (in code terms, like electrical codes):
Yes, your understanding is essentially correct. "Fraction thereof" means any portion of the specified unit. So, in your receptacle example: 2 ft or less requires 1 receptacle. 2.1 ft requires 2 receptacles (because you have 2 full "2ft" sections and a fraction of another). 3 ft requires 2 receptacles. 4 ft requires 2 receptacles 4.1 ft requires 3 receptacles.

Major Fraction Thereof



This is where the nuance lies. "Major fraction" usually means more than half the unit. This is a common convention in many contexts, not just electrical codes. Example

If a rule states "one unit is required for every 10 feet, or major fraction thereof," then: Up to 5 feet: Requires one unit 5.1 feet or greater up to 10 feet: Requires one unit. 10 feet: Requires one unit. 10.1 feet up to 15 feet: Requires two units

Important Considerations



Context is Key

Always read the specific code or regulation carefully. The exact definition of "fraction thereof" or "major fraction thereof" could be explicitly defined within the document. If the code or standard defines these terms differently, then use that definition.

Rounding

Codes often (but not always) implicitly involve rounding up when dealing with "fraction thereof". This is why a fraction triggers the requirement for the next full unit.

Specific Codes Vary

Building codes, electrical codes, plumbing codes, etc., all have their own specific language and definitions. What applies in one code might not apply in another. Always refer to the relevant code for the specific situation.

In summary



Fraction Thereof

Any portion of the base unit triggers the requirement for the next full unit.*

Major Fraction Thereof: Usually means more than half of the base unit triggers the requirement for the next full unit. However, ALWAYS check if the code specifically defines this term.By understanding these nuances, you can accurately interpret and apply code requirements. Good luck! Flag for review