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
1 members (CoolWill), 250 guests, and 13 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Joined: Jul 2002
Posts: 38
E
Electra Offline OP
Member
My question is concerning transformers over 600V. The sizes of fuse or circuit breaker protection is based off of Table 450-3(a) (1999 Code).

Why is the size of a circuit breaker permitted to be larger than a fuse?

I thought that fuses would offer better performance and therefore be allowed to be rated higher.

I thank you for any guidance you can give me on this.

Joined: Mar 2002
Posts: 582
R
Ron Offline
Member
You will find a similar situation for motor short cirucit protection from Table 430.52. Fuses get set tighter to the load than breakers to avoid false trips.


Ron
Joined: Jul 2002
Posts: 38
E
Electra Offline OP
Member
Thank you very much. That makes perfect sense.


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