2017 NEC 338.10(B)

JDB3

Senior Member
Your opinion please. The way I read this, SEU & SER, above size 10, we may now use the 75 degree rating. So #4 SER Al. can now be used as 65 degrees and connected to a 70 amp breaker. :happyyes:
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Amazing how long that took. I will be interesting to go back and read the ROPs to see the reasoning for the 1st change and then the reversal. Its the same cable now as it was in '08 (or '05, I can't recall) when it became restrictive.
 

JDB3

Senior Member
Amazing how long that took. I will be interesting to go back and read the ROPs to see the reasoning for the 1st change and then the reversal. Its the same cable now as it was in '08 (or '05, I can't recall) when it became restrictive.

Never had had a problem with it before the 60 degree rule. To me, if it isn't broke, why fix it:roll:
 

MasterTheNEC

Host of ElectricianLIVE.com
Location
McKinney, Texas
Occupation
Master Electrician & Director of Codes and Standards
I know that Terry Cromer our NC Association of Electrical Contractors director was very vocal on this as he has been for many code cycles.
This was pushed by the wire and cable folks......Made sense since the conductors inside are more than likely 75C and in some cases even 90C insulation. The argument was that (and their still is not any known) type SE Cable was evaluated using the same specifications as Type NM-B and as such the 60C was to be used...due to their similarity. However, no one could produce anything for SE as tested like NM-B so that lack of information supported the face the inners are again rated for 75C or even 90C from some manufacturers.

The other argument was that normal Type NM-B also has conductors rated higher than 60C...but limited by 334.80 and based on tests that were done by NEMA and others. Not sure anyone will try to buck that pig next cycle..I sure am not.
 

MasterTheNEC

Host of ElectricianLIVE.com
Location
McKinney, Texas
Occupation
Master Electrician & Director of Codes and Standards
I thought Southwire were the ones that did the study that was the substantiation for the 60C

They may have contributed to NEMA and UL in the study. Last year I approved over $100,000 in sample wire for the bending study in 312.6....so it is possible they did but it was driven by UL and NEMA.
 

MasterTheNEC

Host of ElectricianLIVE.com
Location
McKinney, Texas
Occupation
Master Electrician & Director of Codes and Standards
It makes no sense since there was no real world evidence of a problem despite millions of cables in service for decades.
I am sure that was also part of the argument.....it happens many times where someone asks how this or that happened....and the room goes silent.
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
Licensed Electrician

peter d

Senior Member
Location
New England
That's an interesting study. I still say there was no real world evidence of cable failures that merited a code change three or four cycles ago, and the most recent code change back to the way things used to be puts an exclamation mark on that.


Yup, hence why I ignored that rule completely. :thumbsup:
 

kwired

Electron manager
Location
NE Nebraska
It's posts like this that get you the hack title.
I ignored it as well, but mostly because I can't recall last time I ever touched "new" SE cable. Likely have touched existing cables a time or three in the past 6-10 years, but most of them were likely touched because they were being removed.

SE cable just isn't that common anymore around here for new installations.
 

mbrooke

Batteries Included
Location
United States
Occupation
Technician
This was pushed by the wire and cable folks......Made sense since the conductors inside are more than likely 75C and in some cases even 90C insulation. The argument was that (and their still is not any known) type SE Cable was evaluated using the same specifications as Type NM-B and as such the 60C was to be used...due to their similarity. However, no one could produce anything for SE as tested like NM-B so that lack of information supported the face the inners are again rated for 75C or even 90C from some manufacturers.

The other argument was that normal Type NM-B also has conductors rated higher than 60C...but limited by 334.80 and based on tests that were done by NEMA and others. Not sure anyone will try to buck that pig next cycle..I sure am not.

Well, I say well done! :D And finally :thumbsup:
 
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