Why are TIA's, put out like that ?
Does the issue itself cause this to be done?
Any body got a layman's answer on this (other than going and reading the subcommittees rules) ?
Errata is for just that...typos in the book, not for actual code changes which this is. I assume that there was a computer power panel manufacturer that wanted to build a panel with more than 42 spaces and he could not without this code change. This is a tentative change and will become part of the process for the 2011 NEC.That one has me baffled as well. Why not just put it in the errata? It seems so trivial.
Errata is for just that...typos in the book, not for actual code changes which this is. I assume that there was a computer power panel manufacturer that wanted to build a panel with more than 42 spaces and he could not without this code change. This is a tentative change and will become part of the process for the 2011 NEC.
http://www.nfpa.org/assets/files/PDF/Standards%20Council/FD08-7-36-dD08-17NFPA70.pdf
The code section that the TIA applies to does not reference a section that has been deleted. It is a stand alone code rule that limits the number of OCPDs in a panel to 42.Don, I see what you're saying, but this TIA appears to address what I consider a typo.... a reference to a requirement that no longer exists.
The fact that the rule has been removed in Article 408 has no effect on this rule as the Chapter 6 rules modify the Chapter 1 through 4 rules. With the removal of the rule in 408 there is no technical reason for the rule to remain in 645, but the fact that it was left there in not a typo. The removal requires panel action just like any code change proposal.645.17 Power Distribution Units.
Power distribution units that are used for information technology equipment shall be permitted to have multiple panelboards within a single cabinet, provided that each panelboard has no more than 42 overcurrent devices and the power distribution unit is utilization equipment listed for information technology application.