ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Violation?
by renosteinke - 01/27/23 09:52 PM
Does NEC 551.71 (F) apply to dwellings?
by BigB - 01/20/23 10:46 AM
Power submeter connections
by HotLine1 - 01/19/23 09:09 AM
AFDD's coming to the UK
by Texas_Ranger - 01/17/23 07:22 PM
New in the Gallery:
Burger King crown sillyness
Burger King crown sillyness
by wa2ise, December 11
240/208 to a house
240/208 to a house
by wa2ise, October 9
Who's Online Now
0 members (), 19 guests, and 16 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#201260 05/23/11 10:22 AM
Joined: May 2010
Posts: 30
B
Bravo Offline OP
Member
I have a situation where I client wants to use 500-kcmil THWN copper conductors, 75deg (380A) protected by a 400A OCPD. Please correct me if I am wrong but in accordance to 240.4 this is allowed as long as the calculated load does not exceed the ampacity of the conductors (380A)?

I need help clarifying part (B). The OCPD is 100% rated with adjustable trip unit. Our firms's licensed engineer will not stamp dwgs if the breaker is 100% rated and does not trust that the trip will be adjusted in the field.

again I need understanding what part (B) is stating.

Thanks in advance.

I have in the process of updating my profile.
My email is dean.vanetten@mwgroup.net.

Stay up to Code with the Latest NEC:


2020 NEC & Related Reference & Study Guides
2020 NEC & Related Reference & Study Guides
Pass Your Exam the FIRST TIME with these Exam Prep Combos:
 

>> Master Electrician Exam Prep     >> JourneyMan Electrician Exam Prep
 

Bravo #201261 05/23/11 11:02 AM
Joined: Dec 2002
Posts: 330
S
Member
According to your reference in 240.4B yes it is allowed. As an Engineer, he has the final say as to what he will stamp and what he won't, whether it meets code or not. Good design may have other reasons may preclude the use of the 400 amp, 100% rated breaker. Anyway, it is his choice to stamp or not, right or perceived wrong.

Look for options acceptable to him, such as a 100% rated braker with (I guess they may be called) replacable current modules. Or a permanent plaque stating maximum rating the breaker may be adjusted to.

Bravo #201262 05/23/11 11:03 AM
Joined: Dec 2002
Posts: 330
S
Member
AND or her.

Bravo #201266 05/23/11 01:45 PM
Joined: Apr 2002
Posts: 7,333
Likes: 7
Member
Dean:
Did you read 240.6 (C)from 2008, that may be an acceptable option to present to the Engineer.

As Sabrown said, the Engineer of record has the ultimate & final say.



John
Joined: May 2010
Posts: 30
B
Bravo Offline OP
Member
Sabrown,

Good point, but even a plaque indicating max rated adjustment cant stop someone from setting trip higher than ampacity.

Dean

Joined: May 2010
Posts: 30
B
Bravo Offline OP
Member
That is also a valid point. Restricting the access to adjusting the trip unit helps along with a plaque indicating max trip setting allowed. Thank you


Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *
2023 National Electrical Code (NEC)
2023 NEC Now Available!
 
* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
sparky66wv
sparky66wv
West Virginia
Posts: 2,236
Joined: November 2000
Top Posters(30 Days)
BigB 4
triple 3
Popular Topics(Views)
302,752 Are you busy
231,974 Re: Forum
216,692 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5