ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Photo Editing Software?
by Fridayrack - 12/03/21 05:05 AM
Square D "All-In-One" Panelboard
by NORCAL - 11/30/21 12:48 PM
Where is Everyone?
by luckyshadow - 11/21/21 10:14 AM
It's been an interesting career
by The Watt Doctor - 11/19/21 09:56 AM
Well I am back to stay (nearly 6 years)
by The Watt Doctor - 11/19/21 09:17 AM
New in the Gallery:
240/208 to a house
240/208 to a house
by wa2ise, October 9
Now you know.
Now you know.
by Tom_Horne, September 7
Who's Online Now
0 members (), 46 guests, and 15 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#86587 11/13/03 08:29 AM
Joined: Apr 2002
Posts: 178
R
Member
Can some explain the current fault conditions.I was explaining to a guy about inrush current on breaker being more than breaker set point for a short time period before it trips.I really don`t feel I`ve done a good job explaining it so I`m asking for some assistance.How does a breaker lets say 40 amp double pole square D home line work to protect agaist fault current.

2017 / 2014 NEC & Related Books and Study Guides
#86588 11/13/03 08:58 AM
Joined: Mar 2001
Posts: 2,056
R
Member
Most convebtional CB's have a thermal component which responds, (relatively slowly)
to lower level overloads in a manner which is inversely proportional (time v. current)to the overload.
There is also a magnetic component, which in the event of a ground-fault or short-circuit, will respond almost instantaneously to this, normally much higher level of overcurrent.

#86589 11/13/03 11:01 AM
Joined: Apr 2002
Posts: 2,527
B
Moderator
Another term for how breakers and fuses react to overcurrent is an inverse time-current characteristic. Simply—the higher the current, the faster the device operates.

Detail: www.usace.army.mil/publications/armytm/tm5-811-14/

Quickie: www.cbibreakers.com/magnetic.asp?menu=sixth


Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *

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

 

Member Spotlight
NickD
NickD
Amish Country, PA
Posts: 46
Joined: March 2013
Top Posters(30 Days)
dsk 2
NORCAL 1
Popular Topics(Views)
286,522 Are you busy
218,952 Re: Forum
205,076 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5