- Location
- Massachusetts
I really wish I could be a fly on the wall when the CMP goes over this one.
A sincere pat on the back to George for going big, I think the change he suggests is a very good one.
A sincere pat on the back to George for going big, I think the change he suggests is a very good one.
I hope you packed a lunch. Please recognize that this proposal took a lot of time to organize and
assemble, and we'll take what we can get. You've got a few options beyond "reject", and there is a lot of good here to
pick from.
In general, all of these changes are intended to increase clarity and usability, drawing inspiration from 3.3.1, 3.3.2,
3.3.3, 3.3.4 and 3.3.5 of the Style Manual. As it stands, 310.15(B) is kind of randomly constructed, with tables intruding
in the middle of sentences repeatedly. By grouping similar concepts, it should be easier to locate where similar sections
belong and avoid scabbing in new requirements at random in future cycles.
This is as good a time as any for a thorough housecleaning.
Starting at the beginning: Part III: This section is different than the rest of the Article, it deserves it's own Part. If you
take this opportunity to split what I have split into more sections, then this action will make even more sense. As time
goes by, and more tables are added, it may help the panel by eliminating references that have already been pointed
simply at Part III.
Part IV: Let's use Article 430 as a model - they had six tables, put them apart from the sections in violation of the
manual of style, and it's a beautiful thing. By assigning the tables their own part, they will no longer be injected into the
middle of requirements, making them exponentially harder to follow. Again, since the user gets to pick their own Table,
depending on which suits their needs, this actually makes a lot of sense. Direct people at Part IV and be done with
them. Part V: Conductors over 2000 Volts separated out for clarity.
Creating a new section is necessary to reduce the "super-listing" aspect of this section. I think the sections I
have moved to 310.14 make for an excellent preface to the meat of this material that remains in 310.15.
Self Evident, these sections created the move.
This is more general information about conductors that is helpful, but not usually pertinent in the moment
that ampacity is being considered, and rarely referred to.
Again, this is general information and belongs in with the general section.
Relocated from (B)(3)(b). Conduits and tubing are the two types of raceway, so the extra language was
dropped and the title changed.
I have never seen an engineered conductor, this rule has probably got one foot in the annex grave
anyway. The cause of getting daily-used ampacity it's own section for clarity is a worthy goal. If the panel feels better
assigning this 310.15(D), I'd still declare victory over this one.
Since this rule ignores the new section 310.15, as it does not comply with the concepts in new (B) and (C),
perhaps it can cloud up new section 310.14 instead (until you read my next proposal and decide to delete it.)
You boys caught us napping, and switched the names of the Tables. The parent section 310.15 should be
changed back to reference Table 310.16, and so on. Sections with little content but with dozen fewer syllables in their
title are featured at the end of this proposal, and are sufficient to meet the Style Manual. Please, return the Tables to
their previous titles. It is a real burden to type or say "Table 310.15(B)(16) six times fast, which is exactly what anyone
who discusses or teaches code has to do. It's not too late to revert back to previous headings.
Different types of conductors are presented here in parallel per MOS 3.3.5. Note that exceptions have been
painstakingly added where appropriate. For the beginning code user, an exception can help elaborate a rule as well as
the rule itself. By deleting all exceptions out of the 2011, it was not as clear.
Simple declarative sentence, specifically constructed in this manner to match (A)(2) below. Additionally,
this removes any question as to whether both travelers of a set in threeway switching count as current-carrying
conductors. I know the panel has stated that it already said that, but I don't see it in existing text. It's a harmless addition
for clarity's sake.
(Relocated from (B)(5) ) The list is presented in a simple declarative form. The terms "2-wire" and
"3-wire" have been replaced by a clear statement of how many ungrounded and grounded conductors in each scenario,
to prevent any confusion about the roles of the wires. For example, does that "3-wire" include the ground? Additionally,
in general, the NEC uses the term "grounded conductor" and therefore increases the ease of use if this section
complies. If the panel would like to retain some of the information previously included, it can be added as an
informational note. Alternately, you can save ink and change the title to "neutral conductor" and retain the "grounded
conductor" language in the subsections, to make it darned clear that if it counts as a CCC, it's not a neutral conductor.
Also, note the intentional progression of the grounded conductor types, and the very careful choice of language. We
identify the system first, and then describe the circuit, to eliminate confusion and enhance readability.
New text: Previous editions of the code did not clarify the status of a neutral conductor in a single
phase 2-wire circuit.
(Relocated from (B)(5)(a))
(Relocated from (B)(5)(b),) Edited to include the status of a single ungrounded conductor from a
Printed on 11/25/2011 13
Report on Proposals ? June 2013 NFPA 70
3-phase system and neutral.
(Relocated from (B)(5)(a))
Exception: (Relocated from (B)(5)(c)) Changed to an exception, as it is the opposite of the normal condition.
Exceptions are not the devil, repeat after me!
( Relocated from (B)(6) )
This subsection is broken into two basic concepts:
1. Conductors inside a cable or raceway require derating by the usual table.
2. Cables grouped together require derating by the usual table.
3. Other wiring methods are derated according to their own unique rules.
The original (B)(3)(a) is a long sentence trying to convey too much too quickly. By breaking it up this way, this section
is clarified. Sure, the rules are essentially the same for both 1 and 2, but as presently worded it looks like any conductor
interior to any enclosure routed close to another conductor is at risk for adjustment. By breaking them up, it is clear that
we are dealing with the wiring methods between enclosures, not the contents of enclosures themselves.
If I have misread this, and you intend for cabinets, boxes, and enclosures to be included in ampacity adjustment (for
example, the interior of a panelboard to count against (existing) 310.15(A)(1) exception), then by all means add new
section 310.15(B)(6) and leave absolutely no doubt.
I interpreted "Where the number of current-carrying conductors in a raceway or cable exceeds three" as dealing with a
raceway with just conductors and a cable with just conductors. I interpreted "where single conductors or multiconductor
cables are installed without maintaining spacing for a continuous length longer than 600 mm (24 in.) and are not
installed in raceways" to mean "where single-conductor cables and multi-conductor cables are not installed in raceways"
because single circuit conductors are not permitted to be installed without a wiring method (outside of a cable or a
raceway) (300.3(A)). The UL Wire Marking Guide lists things we would casually call "conductors" as "cables", so where
appropriate, those changes have been made.
(Relocated from (B)(3)(a)). The first sentence was edited to get rid of a dependent clause. I didn't
understand the "Articles 210, 215, 220 and 230" note, and given our instruction from MOS 4.1.1 to not do that once
(much less four times in rapid succession with no verbs) I interpreted it to be a clandestine message from the Taliban
and deleted it.
Exceptions are not the devil; this one does contradict the original rule, and so is clearer as an
exception.
( Inspired by the nebula surrounding (B)(3)(a)(1), (3), (4) and (5) ) There hasn't been an explicit rule
requiring cables bundled together to be adjusted, it has always been surmised by the MC cable exceptions. Once these
exceptions were deleted, it became even less clear.
This states clearly when cables are to be adjusted.
(Relocated from (B)(3)(a)(4) & (5) ) The wording has been revised for clarity. Since it contradicts the
original rule, it has been returned to being an exception. I struggled with the language, but believe this is 100% accurate
(i.e. both MC and AC cables needing to have no
outer jacket, etc.)
( Relocated from (B)(3)(a)(3) ) "Conductors" changed to "Cables" to match the UL Wire Marking
Guide and White Book, as mentioned above.
By placing these items in equal footing as the other two more common rules, it becomes clear that
they do not follow the common rule concepts. By grouping them in a list format, it is easier to access and apply the
rules.
These two subsections were located on opposite ends from each other before, it makes sense for them to
occupy the same subsection.
They work on the same concept.
Content Unchanged.
Content Unchanged.
Substantiated above.
