Looking over the changes to what was previously Table 310.16, does this mean we can no longer use 20A for #14 and 25A for #12 at 60-degree C for derating purposes?
If so, I can see this causing some new installation issues requiring conductor upsizing.
I don't have the 2011 yet. I suppose that may be why other are not jumping in.
Did they change the 60c rating for small conductors?
I can see this affecting motors and HVAC more than derating.
Don't you derate from the 90c?
Good point. I don’t have my new code book in hand yet either, so I guess I’m getting a little bit anxious since around here we have to be ready to hit the ground running on January 1.
Florida won't get around to adopting this until 2012 or later if the past is any indication.
I am really waiting for the handbook CD. I don't travel around much and I am starting to like the CD format.
I will probably just buy it here at ECN. Last time they were about the same as everywhere else and I would just as soon help out these guys.
Greg:
I have a 2011 & the 'free' PDF. When I get home tonite, I'll try to cut/paste 310.16 & get it up here.
I have NOT had any time (to speak of) to open the 2011 yet, & like you, I'm waiting for the handbook & CD.
Here's part of 310.15(b)
"(B) Tables. Ampacities for conductors rated 0 to 2000 volts
shall be as specified in the Allowable Ampacity Table
310.15(B)(16) through Table 310.15(B)(19), and Ampacity
Table 310.15(B)(20) and Table 310.15(B)(21) as modified by
310.15(B)(1) through (B)(7).
The temperature correction and adjustment factors shall
be permitted to be applied to the ampacity for the temperature
rating of the conductor, if the corrected and adjusted
ampacity does not exceed the ampacity for the temperature
rating of the termination in accordance with the provisions
of 110.14(C).
Informational Note: Table 310.15(B)(16) through Table
310.15(B)(19) are application tables for use in determining
conductor sizes on loads calculated in accordance with Article
220. Allowable ampacities result from consideration of
one or more of the following:
(1) Temperature compatibility with connected equipment,
especially the connection points.
(2) Coordination with circuit and system overcurrent protection.
(3) Compliance with the requirements of product listings
or certifications. See 110.3(B).
(4) Preservation of the safety benefits of established industry
practices and standardized procedures.
(1) General. For explanation of type letters used in tables"
Anyone who can enlarge this font, please do so (with my blessings)
Regarding the article HotLine posted above, does this mean we can still us the 90C column for derating purposes for NM cables or must we now start at 60C.
"The temperature correction and adjustment factors shall
be permitted to be applied to the ampacity for the temperature
rating of the conductor, if the corrected and adjusted
ampacity does not exceed the ampacity for the temperature
rating of the termination in accordance with the provisions
of 110.14(C)."
Not to be critical, but....that sounds like one of our (NJ) many lawyers wrote that!
I'm pondering what it says when time permits
I don't read this as changing anything. We have always limited the ultimate ampacity to the rating of the termination.
You just use the 90c column for dealing with ambient temperature and bundled conductor adjustments.
If you are using one of the restricted cables (AC, MC, RX), you end up with the 60c limit anyway.
They did change the name of 310.16 to 310.15(B)(15) but I don't think it changed. (that was a Mike Holt proposal, just to maintain continuity in 310.15)
I just received my 2011 Handbook, so for those still waiting, I assume this means they are now available everywhere.
The change I was asking about above appears to be mostly just the Table numbering and some 60C and 90C ampacity changes.
It looks like they have reduced ampacity for some copper conductors at 60C by 5 Amps, but increased some other aluminum conductors by the same amount.
Thanks Kjay!
I'm waiting for the CD & Handbook combo....
I haven't got any new books yet, Waiting to see what the best deal I can do, plus my state is very slow at adopting the new NEC after it is out.
Harold:
I know what you mean about state adoption, but I get a 'new' NEC ASAP, and the changes ASAP to prepare my courses and for my 'absorbition' time.
My CO rejected the PO request for the '11 NEC for the office to conserve $$ based on 'we don't need it yet'.
John,
I work for 4 different towns and some of my towns would never buy me a code book. Last year was the first time (I believe) that I got code books for every town. They are all watching their money.
So Mike Holt put in the name change thing. 310.16 was pretty easy to remember and has been the same for the last 30 years. It was Table 310.12 in my 1971 Code. So now we have 310.15(B)(16) that is much more difficult to remember and say and write. I wonder when does usability become more important than the Style manual?
It had to be changed if you think about it. When cited all and every know that the table referenced by 310.16 is different than 310.15 (B) 16.
Otherwise, in all correspondence the adjusted values are not apparent.