I am trying to understand parts of the UL 508A and there is a gray area concerning supplementary protection. Is there a simple way to understand the difference between Branch circuit protection, Feeder circuits and how they relate. The application is the main panel feeds a 175A fused knife switch which feeds a 175 CB Thermo_Magnetic trip unit. Then there is a power distribution block feeding a group of Supplementary breakers ( 10a-40a )10 total. The 175A fused knife switch is remotely mounted on the wall. Any help understanding the terminology would be appreciated
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Branch and feeder circuits
- Thread starter jwhitlock
- Start date
- Status
- Not open for further replies.
pierre
Senior Member
- Location
- Westchester County, New York
Re: Branch and feeder circuits
Article 100 has the definitions of Branch Circuit, Feeder, and Service conductors.
240.10 has the requirement for supplementary overcurrent protection. The UL White book has a section on supplementary protection.
You need to be able to properly identify if the supplementary protection you are mentioning is supplementary or branch circuit protection.
Article 100 has the definitions of Branch Circuit, Feeder, and Service conductors.
240.10 has the requirement for supplementary overcurrent protection. The UL White book has a section on supplementary protection.
You need to be able to properly identify if the supplementary protection you are mentioning is supplementary or branch circuit protection.
Re: Branch and feeder circuits
The circuit breakers (10a-50a)I have are definetly classified as supplementary protection. Can the 175A circuit breaker and 175A fuses serve as branch circuit protection?
Then the supplementary protection ( as the circuit breakers are classified as) Could be connected to the load side.
The Main 175 circuit breaker and the supplementary protection are inside the machine control panel. The knife switch is ouside the panel.
In article 100 part of the definition of supplementary protection devices. States that a Branch circuit overcurrent protection device is required in addition to a supplemenary protection device. Does this mean 175A Branch circuit overcurrent protection device can feed a 20A supplemenary protection device?
I have read the documents you spoke about, but I am not overly familar with the code. so terms like service equipment, final branch circuit and overcurrent device are still unclear.
The circuit breakers (10a-50a)I have are definetly classified as supplementary protection. Can the 175A circuit breaker and 175A fuses serve as branch circuit protection?
Then the supplementary protection ( as the circuit breakers are classified as) Could be connected to the load side.
The Main 175 circuit breaker and the supplementary protection are inside the machine control panel. The knife switch is ouside the panel.
In article 100 part of the definition of supplementary protection devices. States that a Branch circuit overcurrent protection device is required in addition to a supplemenary protection device. Does this mean 175A Branch circuit overcurrent protection device can feed a 20A supplemenary protection device?
I have read the documents you spoke about, but I am not overly familar with the code. so terms like service equipment, final branch circuit and overcurrent device are still unclear.
Re: Branch and feeder circuits
Okay, so here's what you do:
Read Article 100 all the way through.
Understand it.
When you're done, read it again.
Then read Art 110.12 paying special attention to Article 110.12.
The way things are today (ALWAYS changing) it's okay not to know everything. It is very important in fact that we acknowledge that we don't know everything. The important thing is that we know where to look when we don't.
True Story,
RSvetti
Okay, so here's what you do:
Read Article 100 all the way through.
Understand it.
When you're done, read it again.
Then read Art 110.12 paying special attention to Article 110.12.
The way things are today (ALWAYS changing) it's okay not to know everything. It is very important in fact that we acknowledge that we don't know everything. The important thing is that we know where to look when we don't.
True Story,
RSvetti
- Status
- Not open for further replies.