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Thursday, March 2, 2017
Question:
Hi everyone,
Would you define the word set in section 230.40? Example: If an electrician has a service requiring 1200 amps for example and does it parallel conductors after the service point and runs those conductors in multiple conduits is the set the whole of all conduits and the conductors or just the conductors within one conduit?
Steve
A
Answer:
Hey Steve thanks for your question. The word "set" is not defined in the NEC but one example at dictionary.com indicates it can be "a number, group, or combination of things of similar nature, design, or function: a set of ideas". In 230.40 it refers to a "group (set) of conductors" that are used together to supply a "group" of service entrance conductors. Notice the word "set" is only used where the term "conductors" is used. It is not used with "service drop" and "service lateral" even though each of those would have a "group of conductors" because the terms are singular.
As an example if three phase conductors and a grounded neutral conductor are used as service conductors (in a set) they can only supply three phase conductors and a grounded neutral conductor used as service entrance conductors (in a set) as stated in 230.40. The exceptions allow additional "sets" of conductors for multiple occupancy buildings, more than one service disconnecting means, etc.
The word "set" is also often used to describe installations of conductors connected in parallel even though the word "set" is not used in 310.10(H). So some would likely say that in your parallel example each group of ABC&N would be a set - that is not how the word set is used in 230.40.
It is also interesting to note that the word "set" is not used for feeder conductor applications in Article 225 although the same conductor arrangement used for services in Article 230 could exist. Maybe this is an opportunity to improve the NEC usability for 2020 but it would probably need to be a collective effort. Renumbering Articles 225 and 230 using a consistent format where possible might be a good starting point.