ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Increasing demand factors in residential
by gfretwell - 03/28/24 12:43 AM
Portable generator question
by Steve Miller - 03/19/24 08:50 PM
Do we need grounding?
by NORCAL - 03/19/24 05:11 PM
240V only in a home and NEC?
by dsk - 03/19/24 06:33 AM
Cordless Tools: The Obvious Question
by renosteinke - 03/14/24 08:05 PM
New in the Gallery:
This is a new one
This is a new one
by timmp, September 24
Few pics I found
Few pics I found
by timmp, August 15
Who's Online Now
0 members (), 255 guests, and 16 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#80168 03/11/02 10:37 PM
Joined: Oct 2001
Posts: 45
W
Member
I went to a service call lately to a medical office to add some isolated ground circuits for computers. I was shocked to find that the majority of the wiring, more than thirty 110V circuits, was done in 16ga MTW/THHN in EMT on 15 amp breakers. The service is 200 amp single phase and there are no problems with the installation of the service equipment or the load center. The building is less than 10 years old. It is in an area where there are no inspections or licensing required. I was taught to never use less than 12ga wire in commercial buildings and that is what I have always done but I can't find the code to back it up. I want some really solid ground to approach the owners with to convince them to do something about it. Can anyone help me with code references? Thanks!

Stay up to Code with the Latest NEC:


>> 2023 NEC & Related Reference & Exam Prep
2023 NEC & Related Reference & Study Guides

Pass Your Exam the FIRST TIME with the Latest NEC & Exam Prep

>> 2020 NEC & Related Reference & Study Guides
 

#80169 03/11/02 11:05 PM
Joined: Oct 2000
Posts: 4,116
Likes: 4
Member
WW,

Although 12 ga minimum is a good policy to go by I don't know of any rules requiring that. There is one though that specifies 14 ga minimum see 310.5

Bill


Bill
#80170 03/11/02 11:56 PM
Joined: Oct 2001
Posts: 45
W
Member
Bill, I saw that and my interpetation was that anything smaller than 14ga could only be used in fixtures and control panels but not for fixed wiring in a building. The ampacity of the 16ga THHN is 18 amps, so I guess it is not overloaded, but it still seems very strange to me. The 12ga minimum size for commercial buildings may have been a local code in places I have worked over the years and it just stuck with me. Thanks for the reply.

#80171 03/12/02 12:31 AM
Joined: Oct 2000
Posts: 4,116
Likes: 4
Member
Quote
my interpetation was that anything smaller than 14ga could only be used in fixtures and control panels but not for fixed wiring in a building.

Your statement is correct. 16 ga should not be used for the wiring in this building. In Table 310.16 that 18a you see is under the 90C column and that could only be used if wiring was connected to terminals with a rating of 90C. Breakers are either 60C or 75C (some older ones even 40C) If you notice, there is no ampacity under the 60C and 75C columns for 16ga wire.

Bill

[This message has been edited by Bill Addiss (edited 03-11-2002).]


Bill
#80172 03/13/02 10:17 PM
Joined: Mar 2002
Posts: 582
R
Ron Offline
Member
240.4(D) limits 15 ampere max. overcurrent protection for #14 awg.


Ron

Link Copied to Clipboard
Powered by UBB.threads™ PHP Forum Software 7.7.5