Short Circuit Level at Panel Board
- Thread starter TMMB
- Start date
- Status
If the specifications are for a "fully rated system" then all over current devices would need to be rated 25k or above,
If a "series rated system" is acceptable, then you can look at each breaker and see if it is shown by the manufacturer to series rate with the over-current device ahead of it to 25k.
If a "series rated system" is acceptable, then you can look at each breaker and see if it is shown by the manufacturer to series rate with the over-current device ahead of it to 25k.
- Location
- Illinois
- Occupation
- retired electrician
"Series" is the correct term. It is where the main breaker is listed for the full available fault current and the downstream breakers are rated for a short circuit current that is less than the available fault current. This is listed and tested combination of breaker where the upstream breaker will protect the downstream breaker. In many cases both breakers will open to clear the fault. See 240.86.
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
It can be valid either way, depending on the UL listings and tested combinations.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Typical 'miniature' breaker panelboard is a good example. The main breaker is usually 22k rated but the branch breakers are usually only 10k rated, but have been tested and rated for series with the 22k main.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Series ratings between breakers and fuses, often requires the use of Class J instead of typical Class R.
- Status