- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
How about cutting off the nose to spite the face? 
1.) NEC Section/Paragraph: 225.39, including subsections
2.) Proposal Recommends: [delete text]
3.) Proposal: Delete this section.
4.) Substantiation: Currently, this section is unclear as to what the "rating" requirement is referring to. Some view it as an addition of the ratings of the breakers installed at the separate structure in the panel(s). Some view it as a rating requirement for the enclosure itself. Some even view it as the rating for the OCPD that is installed at the supply side at the originating building, protecting feeder conductors.
In any case, it appears evident that the size of conductors feeding the disconnecting means are truly what constitute the capacity of the system, and those conductors are sized and installed independent of the requirements laid out in this section.
Given the requirement given in 225.36, it appears that the purpose of this area of Article 225 is geared towards the ease of future expansion: should a seperate structure at some point be supplied by a separate service, such an improvement would be made easier if the existing equipment were already suitable for such use. The requirements of this area are a reflection of nearly identical requirements of Article 230.
However, section 90.1(B) states that compliance with the NEC "...will result in an installation that is essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use." There is no hazard that is prevented by this section, it appears to exist solely for future expansion, which is explicitly outside the desired scope of the NEC per 90.1.
Further, if such an improvement is made to a structure at a later date, it is probable that most if not all equipment supplying that structure will be removed due to age or fundamental changes in the use of the building requiring greater capacity.
Given the rampant misunderstanding of the nature of this section, if it is retained the language should be clarified to reflect what exact component of the system is to bear the ratings listed in (A) through (D).
1.) NEC Section/Paragraph: 225.39, including subsections
2.) Proposal Recommends: [delete text]
3.) Proposal: Delete this section.
4.) Substantiation: Currently, this section is unclear as to what the "rating" requirement is referring to. Some view it as an addition of the ratings of the breakers installed at the separate structure in the panel(s). Some view it as a rating requirement for the enclosure itself. Some even view it as the rating for the OCPD that is installed at the supply side at the originating building, protecting feeder conductors.
In any case, it appears evident that the size of conductors feeding the disconnecting means are truly what constitute the capacity of the system, and those conductors are sized and installed independent of the requirements laid out in this section.
Given the requirement given in 225.36, it appears that the purpose of this area of Article 225 is geared towards the ease of future expansion: should a seperate structure at some point be supplied by a separate service, such an improvement would be made easier if the existing equipment were already suitable for such use. The requirements of this area are a reflection of nearly identical requirements of Article 230.
However, section 90.1(B) states that compliance with the NEC "...will result in an installation that is essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use." There is no hazard that is prevented by this section, it appears to exist solely for future expansion, which is explicitly outside the desired scope of the NEC per 90.1.
Further, if such an improvement is made to a structure at a later date, it is probable that most if not all equipment supplying that structure will be removed due to age or fundamental changes in the use of the building requiring greater capacity.
Given the rampant misunderstanding of the nature of this section, if it is retained the language should be clarified to reflect what exact component of the system is to bear the ratings listed in (A) through (D).
