ser cable 60 deg or not?

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trex

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Hey guys - would like an opinion. To start out with I am working under the 2008 code, we have inspectors in our part of the state that are requiring 300 AL SER cable to feed a 200 amp subpanel. They are using Art. 338.10 B4 for this requirement stating it needs to be figured under the 60 degree column. I am contending this is incorrect according to Art. 215.2 A3. I feel 4/0 AL would be correct per Table 310.15 B6. And by the way, these are residential installations. What do you think?
 
trex said:
Hey guys - would like an opinion. To start out with I am working under the 2008 code, we have inspectors in our part of the state that are requiring 300 AL SER cable to feed a 200 amp subpanel. They are using Art. 338.10 B4 for this requirement stating it needs to be figured under the 60 degree column. I am contending this is incorrect according to Art. 215.2 A3. I feel 4/0 AL would be correct per Table 310.15 B6. And by the way, these are residential installations. What do you think?
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SE cable is a 60 deg conductor when used indoors. See 338.10(B)(4)(a). (Compare the wording from the '05 to the '08)

Also, 310.15(B)(6) only applies if the feeder is carrying the entire load of a dwelling unit.
 
trex said:
Hey guys - would like an opinion. To start out with I am working under the 2008 code, we have inspectors in our part of the state that are requiring 300 AL SER cable to feed a 200 amp subpanel. They are using Art. 338.10 B4 for this requirement stating it needs to be figured under the 60 degree column. I am contending this is incorrect according to Art. 215.2 A3. I feel 4/0 AL would be correct per Table 310.15 B6. And by the way, these are residential installations. What do you think?
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Trex, art. 215(A)(3) , what does it mean to be larger. In your case, if you used 4/0 alum. from the meter base to main disconnect then you are satisfying art. 310.15(B)(6) but is 3/0 copper considered smaller than 4/0. No it actually has a greater ampacity than 4/0 AL.

Now let's look at the reverse. I use 3/0 copper between the meter and the main disco. Now can I use 3/0 AL to the interior panel? You said the feeder needs not be larger than the service conductors. See my point.

My opinion is that the word "larger" was taken out of art. 310.15(B)(6) and never got taken out or reworded in art. 215(A)(3).
 
trex, As Dennis has noted and as the link supports, I'm afraid you are in an area where you very well might get different interpretations from different inspectors. Some say 215.2 "overrides" 338.10, some don't.
 
Thats the problem we are having in this State since the option of '08. It's all very clear to everyone, just not the same "clear":)
 
iwire said:
You guys have lost me, I feel it is all very clear.
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Yeah well I read through that entire thread and it is not so clear to me. The end conclusion was- I guess the NEC can require the feeder to be larger than the SE conductors and, oh yeah, your going to have to install wires bigger than the terminal lugs will except....

Absurd. What did they do....
 
Dennis Alwon said:
My opinion is that the word "larger" was taken out of art. 310.15(B)(6) and never got taken out or reworded in art. 215(A)(3).
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The requirment to not be larger is still in 310.15 (B) (6) of the 2008 NEC. (as well as 215.2 (A) (3)).
The OP states a sub panel (undefined) I think that term is a remote panel supplying part of the load within a dwelling (I undrstand the 3-0 @200A).

So there is a little confusion. If in fact as Dennis (i believe) is stating the feeder is supplying the entire load in or associated with the dwelling unit, then the code does not require the feeder to be sized larger than the SE Conductors. UNLESS it is SER .

This was a great discussion at a inspectors seminar on Cape Cod. If you can be paticent I think the 2011 may help.
 
cpal said:
The requirment to not be larger is still in 310.15 (B) (6) of the 2008 NEC. (as well as 215.2 (A) (3)).
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Could you show me where it says larger. I see this and I do not see the word larger

6) 120/240-Volt, 3-Wire, Single-Phase Dwelling Services and Feeders. For individual dwelling units of one-family, two-family, and multifamily dwellings, conductors, as listed in Table 310.15(B)(6), shall be permitted as 120/240-volt, 3-wire, single-phase service-entrance conductors, service-lateral conductors, and feeder conductors that serve as the main power feeder to each dwelling unit and are installed in raceway or cable with or without an equipment grounding conductor. For application of this section, the main power feeder shall be the feeder between the main disconnect and the panelboard that supplies, either by branch circuits or by feeders, or both, all loads that are part or associated with the dwelling unit. The feeder conductors to a dwelling unit shall not be required to have an allowable ampacity rating greater than their service-entrance conductors. The grounded conductor shall be permitted to be smaller than the ungrounded conductors, provided the requirements of 215.2, 220.61, and 230.42 are met.
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yes I see your point 215 says larger and 310.15 states greater ampacity.
Well thats what happens with two different CMP's The TCC maight pick up such inconsistancies but its a big book. I think the intent is consistant, its the minusa of the written word that appears to cause concern.

As a wise individual always said the code is language Vs intent.
 
If we dare get into intent, Southwire states from their Code gurus that the intent was to de-rate SE cables when installed in interior insulation.
They say that in 2011 this will all be clear :)
 
augie47 said:
If we dare get into intent, Southwire states from their Code gurus that the intent was to de-rate SE cables when installed in interior insulation.
They say that in 2011 this will all be clear :)
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Yes that was the discussion
 
People in Washington state have this great little publication and here is what they say about it,.. I wish my state had a similar publication

http://www.lni.wa.gov/TradesLicensing/Electrical/files/currents/elc0901.pdf

We have been asked for further clarification of this issue for use of service entrance cables under the
unique conditions allowed in NEC 310.15(B)(6) and Table 310.15(B)(6). In this application the rating of
the SE and USE conductors is increased to a higher ampacity based on the diversity of load on any
service or feeder conductors carrying the full load of an individual dwelling unit, as limited in 310.15(B)(6).
Loads on such conductors are considerably less than the load calculated per Article 220. No restrictions
on these long established Table 310.15(B)(6) ratings were supported by CMP 6, the panel responsible for
Article 310. We will not restrict these table ratings any further (for interior installation) under these specific
conditions of use.
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That helps, but for sake of argument the rational that cause CMP 7 to change the language in the 08 and the concerns of panel 6 regarding 310.15 (B) (6) were not necessarly the same.

Don't be surprised if panel 6 has some action on the table.
 
trex said:
Hey guys - would like an opinion. To start out with I am working under the 2008 code, we have inspectors in our part of the state that are requiring 300 AL SER cable to feed a 200 amp subpanel. They are using Art. 338.10 B4 for this requirement stating it needs to be figured under the 60 degree column. I am contending this is incorrect according to Art. 215.2 A3. I feel 4/0 AL would be correct per Table 310.15 B6. And by the way, these are residential installations. What do you think?
Click to expand...

The other thing is ,.. this would also effect the meter can and perhaps the panel as well ,...I hope they look long and hard at this ,.. I'm not sure there is an issue with the millions that are installed per xxx.xx(B)(6) that would demand such a change

http://www.iaei.org/magazine/departments/ulquestion_html/08eul3.html

......Requirements for wire bending space and the conductor size a terminal is rated to terminate are reduced to account for the reduced size conductor. For example: NEC Table 310.16 would require 3/0 Copper for 200 A service, while UL 414 would allow 2/0 if marked for this application [which is in agreement with conductor ampacities provided in NEC Table 310.15(B)(6)]. These meter sockets have not been evaluated for applications that go beyond this limitation......
Click to expand...
 
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