SER and SEU...

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chevyx92 said:
Under the 2005 NEC what column do you size under, 60 degree or is it the 75? I heard this had changed, when??
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2005 you use 75C and 2008 you use 60C. For derating you may use 90C for both.

Remember if it is for Service and not a feeder then the 75C still is applicable.
 
Dennis Alwon said:
2005 you use 75C and 2008 you use 60C.
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Im sure you would have added this if you felt like typing.. Unless the breaker 100 amps and less is only rated for 60 c.Then you can only rate the cable as 60 c.

Rick
 
chevyx92 said:
Under the 2008 as well or just 2005?
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The 2008 change only pertains to the interior wiring of buildings. Also for any location if the termination are only rated for 60 c and the breaker is 100 amps or less, the conductors are limited to 60 c rating.
Rick
 
mark32 said:
Which article contains this change, I can't find it.
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338.10 Uses Permitted.
(4) Installation Methods for Branch Circuits and Feeders.
(a) Interior Installations. In addition to the provisions of this article, Type SE service-entrance cable used for interior wiring shall comply with the installation requirements of Part II of Article 334.

334.80 Ampacity.
The ampacity of Types NM, NMC, and NMS cable shall be determined in accordance with 310.15. The ampacity shall be in accordance with the 60?C (140?F) conductor temperature rating. The 90?C (194?F) rating shall be permitted to be used for ampacity derating purposes, provided the final derated ampacity does not exceed that for a 60?C (140?F) rated conductor. The ampacity of Types NM, NMC, and NMS cable installed in cable tray shall be determined in accordance with 392.11.
 
Thank you RUWired. Just so I am on the same page as everyone else lets look at a common scenario. Someone runs #2 aluminum SER to feed a sub panel and even though the terminations are rated 60/75c the SER's OCPD must be sized to the 60c column(?) this case being an 80 amp breaker sized up one size from 75. Is this correct?
 
mark32 said:
Thank you RUWired. Just so I am on the same page as everyone else lets look at a common scenario. Someone runs #2 aluminum SER to feed a sub panel and even though the terminations are rated 60/75c the SER's OCPD must be sized to the 60c column(?) this case being an 80 amp breaker sized up one size from 75. Is this correct?
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Correct, assuming the actually load is not over 75 amps, IMO, this code change is pretty strange and would really like to see the evidence that before the code change it was a dangerous situation. :roll:
 
Strange indeed Stickboy. I work at HD and guys come in and buy #2 al SER all the time and most want to put it on a 100a breaker. I would tell them it's only rated for a 90 but now it's dropping down to a 70! (Suppose I'd rather do that than up sizing to an 80 as you pointed out)
 
mark32 said:
Strange indeed Stickboy. I work at HD and guys come in and buy #2 al SER all the time and most want to put it on a 100a breaker. I would tell them it's only rated for a 90 but now it's dropping down to a 70! (Suppose I'd rather do that than up sizing to an 80 as you pointed out)
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One exception that would allow the # 2 awg sub panel feed is, if the service conductors are #2 awg al for a 100 amp service, # 2awg for a sub panel would be allow.

215.2 Minimum Rating and Size.
(A) Feeders Not More Than 600 Volts.
(3) Individual Dwelling Unit or Mobile Home Conductors. Feeder conductors for individual dwelling units or mobile homes need not be larger than service conductors. Paragraph 310.15(B)(6) shall be permitted to be used for conductor size.
 
RUWired said:
One exception that would allow the # 2 awg sub panel feed is, if the service conductors are #2 awg al for a 100 amp service, # 2awg for a sub panel would be allow.

215.2 Minimum Rating and Size.
(A) Feeders Not More Than 600 Volts.
(3) Individual Dwelling Unit or Mobile Home Conductors. Feeder conductors for individual dwelling units or mobile homes need not be larger than service conductors. Paragraph 310.15(B)(6) shall be permitted to be used for conductor size.
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Another exception is table 310.15(B)(6) conductor types and sizes for 120/240 volt, 3 wire, single phase dwelling services and feeders. 100 amps, use #4 copper or #2 aluminum
 
frankft2000 said:
Another exception is table 310.15(B)(6) conductor types and sizes for 120/240 volt, 3 wire, single phase dwelling services and feeders. 100 amps, use #4 copper or #2 aluminum
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This is only true if the feeder is on the exterior of the building. Interior wiring with seu or ser as feeders must use the 60C rating.
 
frankft2000 said:
Another exception is table 310.15(B)(6) conductor types and sizes for 120/240 volt, 3 wire, single phase dwelling services and feeders. 100 amps, use #4 copper or #2 aluminum
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#2 Al (and #4 Cu...edit) can be used for a 100A feeder... only ...if that feeder is supplying 100% of the power to the dwelling:smile: .

steve
 
I just looked over my '05 codebook and the NM section pertaining to ampacity (334.80) is, if I'm not mistaken, unchanged to the '08 code. Am I missing something?
 
mark32 said:
I just looked over my '05 codebook and the NM section pertaining to ampacity (334.80) is, if I'm not mistaken, unchanged to the '08 code. Am I missing something?
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The change is in 338.10(B)(4)(a) the words "excluding 334.80" were removed from the end of (a).
 
Dennis Alwon said:
This is only true if the feeder is on the exterior of the building. Interior wiring with seu or ser as feeders must use the 60C rating.
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Where do you find the interior/exterior delineation in the code book? As Hillbilly said if the feeder supplies 100% of the load Table 310.15(B)(6) may be used regardless of where that feeder is installed.
 
infinity said:
Where do you find the interior/exterior delineation in the code book? As Hillbilly said if the feeder supplies 100% of the load Table 310.15(B)(6) may be used regardless of where that feeder is installed.
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How do you interpret 338.10(B)(4)(a)
 
Dennis Alwon said:
How do you interpret 338.10(B)(4)(a)
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IMO that doesn't apply to feeders that fall under 310.15(B)(6) if the service entrance conductors and the feeder are the same size.
 
infinity said:
IMO that doesn't apply to feeders that fall under 310.15(B)(6) if the service entrance conductors and the feeder are the same size.
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Why not. It explicitly says branch circuits and feeders. Is the cable carrying the full load after the main disco not considered a feeder? If it is in the interior and a feeder then this section applies. No exceptions are given.
 
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