ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals

ECN Shout Chat
Top Posters(30 Days)
Admin 16
Recent Posts
fuse rejectors
by gfretwell. 03/23/17 01:12 PM
Another Forum Update
by Admin. 03/22/17 03:04 PM
Dining room plugs
by watersparkfalls. 03/21/17 10:31 PM
TRUE POWER
by jraef. 03/21/17 09:13 PM
WEG CFW-11 Frequency Inverter
by jraef. 03/21/17 08:50 PM
New in the Gallery:
SE cable question
Popular Topics(Views)
231,245 Are you busy
165,957 Re: Forum
160,481 Need opinion
Who's Online Now
0 registered members (), 57 guests, and 10 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#80521 - 04/25/02 08:29 AM Conduit Fill Lighting circuits?  
Reel-Break  Offline
Member
Joined: Apr 2002
Posts: 178
nc
Yesterday we went to a plant where some conductors melted in the conduit.There was several problems all the circuits were over loaded #12`s 20+ amps about 19 8' floresant on each cir.They have 1 1/4 conduit with 36 # 12 conductors all over loaded and the conduit is very hot.The question I have how best to explain to the electrical poeple How to size the number of circuits in a pipe.The code table c8 says they can have 45 in the pipe but I tried explaining that with the ciruits over loaded and the heat generated the fill and current carrying capasity of the wires would be less.I don`t think I did a good job with them understanding so please help us out with some examples and code articals thanks guys.We ran another 1 1/4 conduit over and that reduced the heat and we split the circuits droping the current to each circuit.


2017 / 2014 NEC & Related Books and Study Guides

#80522 - 04/25/02 11:59 AM Re: Conduit Fill Lighting circuits?  
Redsy  Offline
Member
Joined: Mar 2001
Posts: 2,056
Bucks County PA
See table 310.15(B)(2)(a) for adjustment factors.
36 conductors require an ampacity adjustment that results in only 40% of the Table 310.16 values.
In your case (using the 90c column for derating purposes) .4 x 30 amps = 12 amps for #12 copper.


#80523 - 04/28/02 08:29 PM Re: Conduit Fill Lighting circuits?  
Glenn  Offline
Member
Joined: Jan 2001
Posts: 75
Is that 36 ungrounded conductors plus neutrals ?

Many plants have 3Ø 4W so the neutrals would be current carrying also on circuits with ballasts.

If so, could be 35 percent derate.
30A * 0.35 = 10.5 Ampacity.



Member Spotlight
AllClear
AllClear
Belmond Iowa US
Posts: 44
Joined: August 2005
Show All Member Profiles 
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.011s Queries: 14 (0.003s) Memory: 0.7495 MB (Peak: 0.8709 MB) Zlib enabled. Server Time: 2017-03-23 22:11:12 UTC