I installed 175A new breaker and the next day I had to uninstall it and install new 175A breaker and when I asked why, the PM says because the first one is serie breaker. Is this correct?what serie breaker means? Can someone clarify this concep and pros and cons to use serie breaker?
Series breakers?
- Thread starter marcosgue
- Start date
Series ratings are one way to address available fault current. Series ratings requires specific breakers. There are many links the help explain series ratings. I would suggest "Eaton series rating guide"
Last edited:
Thank you @augie47 but if still the series breaker can be able to support the load and protect the cable, in this case what do you consider the reason to change the breaker?something in relation with the coordination studies? This breaker 175A is feeding the chiller equipment with MCA=164A, 480V, 3Ph.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
I believe that if there are not two breakers in series (i.e., the 175 amp and one other between the power panel and the chiller), then the 175 amp breaker having a series rating is irrelevant. It would have been acceptable.
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
A breaker has many ratings: its trip current, its maximum voltage, and its maximum fault current interrupting capacity, among others.
Imagine that you'd installed a 175A 240V breaker. Correct trip rating but the voltage rating is too low for the job. The breaker would likely fail just when it was most needed: as it was trying to trip.
All electrical systems have a maximum available short circuit value, essentially what the transformer can push through the wires into a perfect dead short. The breaker(s) must be able to withstand and open if this maximum possible short circuit is flowing. If the breaker can't handle the available short circuit current, it might fail just when it was most needed.
A fully rated breaker is one that can open against the maximum available short circuit current on its own.
A series rated breaker is _not_ rated to withstand the maximum available short circuit current on its own, but can be used in combination with an upstream breaker or fuse to function with high available short circuit current. The combination of two OCPDs in series is able to open against the fault current.
Imagine that you'd installed a 175A 240V breaker. Correct trip rating but the voltage rating is too low for the job. The breaker would likely fail just when it was most needed: as it was trying to trip.
All electrical systems have a maximum available short circuit value, essentially what the transformer can push through the wires into a perfect dead short. The breaker(s) must be able to withstand and open if this maximum possible short circuit is flowing. If the breaker can't handle the available short circuit current, it might fail just when it was most needed.
A fully rated breaker is one that can open against the maximum available short circuit current on its own.
A series rated breaker is _not_ rated to withstand the maximum available short circuit current on its own, but can be used in combination with an upstream breaker or fuse to function with high available short circuit current. The combination of two OCPDs in series is able to open against the fault current.