ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
Extension cords
by annemarie1. 09/25/18 06:06 PM
220/230/240V 60Hz Systems
by gfretwell. 09/23/18 02:50 PM
Inspection camera help
by petey_c. 09/22/18 07:52 AM
Motion detectors and dimmers
by gfretwell. 09/20/18 04:02 PM
Acronis Backup 2017
by gfretwell. 09/16/18 12:46 AM
New in the Gallery:
Plug terminals
Housebilding DIY wiring
Who's Online Now
0 registered members (), 9 guests, and 23 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Circuit Breakers #65388
05/02/06 12:08 AM
05/02/06 12:08 AM
9
96mystic  Offline OP
Junior Member
Joined: May 2006
Posts: 1
Gresham, Oregon, USA
When sizing a circuit breaker, is it fair to say: multiply the calculated amperage by 1.25 and, if necessary, round up?
Thanks in advance,
Jim Finley


"Tell me, I'll forget".
"Show me, I'll remember".
"Involve me, I'll understand".
Work Gear for Electricians and the Trades
Re: Circuit Breakers #65389
05/02/06 12:12 AM
05/02/06 12:12 AM
F
frenchelectrican  Offline
Member
Joined: Feb 2003
Posts: 939
Wi/ Paris France { France for ...
gernally yes but a catch is it depend on the conductor as well

devices 800 amp and over

where the over current device is rated 800 amp and over the conductors ampcity it protected shall be equal or greater than rating of conductors

device of 800 amp or less
the next stanard overcurrent rating shall be permitted to be used provied all the following condtion are met:

1] the conductors being protected are not part of multioutlet branch circuit supplying for cord and plug connected portable loads

2] the ampacity of the conductors does not corponded with the standard ampre rating of the fuse or circuit breaker without overload adjustment above the ratings

3] the next higher standard rating do not excess of 800 amperes. [ see above ]

merci, marc

[This message has been edited by frenchelectrican (edited 05-02-2006).]


Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)

Re: Circuit Breakers #65390
05/02/06 06:03 PM
05/02/06 06:03 PM
D
Dave T  Offline
Member
Joined: Jan 2005
Posts: 155
Waukesha, WI, USA
It's simple. Calculate the load (125%+100%), select a cable to carry the load (the cable must carry the calculated load), select a breaker to protect the cable (the breaker is based upon the cable's rated ampacity noting the 800a up/down rule as the other poster pointed out).


Featured:

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

 

Member Spotlight
renosteinke
renosteinke
Blue Collar Country
Posts: 5,316
Joined: January 2005
Show All Member Profiles 
Top Posters(30 Days)
Admin 13
BigB 4
Popular Topics(Views)
249,478 Are you busy
187,396 Re: Forum
176,739 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.023s Queries: 14 (0.005s) Memory: 0.9512 MB (Peak: 1.0756 MB) Zlib enabled. Server Time: 2018-09-26 15:25:40 UTC