ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
sec cable code conflict
by gfretwell. 11/17/18 02:19 PM
This anti-theist is priceless!!!
by Texas_Ranger. 11/17/18 02:15 PM
High current GFI vs regular GFCI
by Texas_Ranger. 11/17/18 02:07 PM
Single phase and what you call it.
by dsk. 11/12/18 11:10 AM
New in the Gallery:
What is this for?
Plug terminals
Who's Online Now
0 registered members (), 18 guests, and 26 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Use of 90 degree rated cable #77646
07/06/01 02:08 AM
07/06/01 02:08 AM
T
tmon  Offline OP
Member
Joined: Jul 2001
Posts: 29
In Mike Holts "Masters Electrician Prep Book", he refers to the 90 degree column in T310-16 and states that this column is used primarily for ampacity derating. Has anyone else read or heard this?

2017 / 2014 NEC & Related Books and Study Guides
Re: Use of 90 degree rated cable #77647
07/06/01 05:32 AM
07/06/01 05:32 AM
S
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,371
Hi tmon,
yes , we are allowed to use the highest figure to start derating calc's from, i believe there was a code cycle to clear this up, but am at a loss this morning for an article...

Re: Use of 90 degree rated cable #77648
07/06/01 05:34 AM
07/06/01 05:34 AM
G
Glenn  Offline
Member
Joined: Jan 2001
Posts: 75
It's always been that way.

Most earier Circuit Breakers ( small size ) were rated for 60º terminations.

Now many are rated for 60/75º terminations.

Usually only high voltage systems and bus work is the only items rated for 90º terminations.

Look at the labeling within panels and on equipment terminal info.

Also NEC 110-14(c) must be followed. Although is has only been in the NEC the last few cycles, it has always been in 110-3(b) and the UL White book has had the info for many mnay years, usually with-in the first 8 pages of text.

Glenn

Re: Use of 90 degree rated cable #77649
07/07/01 06:50 AM
07/07/01 06:50 AM
S
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,371
thanks Glenn
[Linked Image]

Re: Use of 90 degree rated cable #77650
07/07/01 01:54 PM
07/07/01 01:54 PM
Scott35  Offline

Broom Pusher and
Member
Joined: Oct 2000
Posts: 2,708
Anaheim, CA. USA
tmon,

Welcome to the group!!!

Just wanted to point out one of the more "simpler" points on using the 90 degree column for derating is the reason we can put upto 9 current carrying conductors [#12 THHN cu] in the same raceway, and still have them rated at 20 amp max.
What is being done here is the 30 amps maximum for #12 in the 90 degree column is used for the derating number - so for 9 current carrying conductors, 70% of 30 amps is 21 amps.

Scott SET.

Quote
Originally posted by tmon:
In Mike Holts "Masters Electrician Prep Book", he refers to the 90 degree column in T310-16 and states that this column is used primarily for ampacity derating. Has anyone else read or heard this?


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
richard
richard
L.I. New York
Posts: 98
Joined: August 2003
Show All Member Profiles 
Top Posters(30 Days)
Admin 7
djk 2
Popular Topics(Views)
251,553 Are you busy
188,713 Re: Forum
178,421 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.017s Queries: 14 (0.004s) Memory: 0.9688 MB (Peak: 1.1088 MB) Zlib enabled. Server Time: 2018-11-18 01:43:59 UTC