Series Rating Good or Bad Idea

[BAHTAH]

I have over the years seen many projects which called for specific Fault Current ratings on service and distribution breakers only to see a general note allowing series rating or no note and someone quoting equipment using series ratings. To inspectors and plan checkers I would ask, does anyone evaluate submitted plans with respect to the NEC limitations on series rating? To those in the field I would ask, do you see the misuse of series ratings in an effort to provide a lower bid price?

 

[dnbob]

Re: Series Rating Good or Bad Idea

I have never seen misuse of series ratings. They are a substantial cost savings compared to a fully rated system. In Arizona, these systems are used in nearly every light commercial and multi-family job. The city of Phoenix is very strict on the uses of these systems, and will not even final a panel if the series ratings installed, do not match exactly to the book that must be provided by the manufacturer and placed in each panel board. In Minnesota, people are not as aware of such a system, even though they are used quite often.

 

[ron]

Re: Series Rating Good or Bad Idea

I dread when I must specify series rated equipment when it relies on a fuse to achieve the required rating.
This only occurs when I specify panelboards and busway above 65k available. Otherwise it is a fully rated system (or a series rating involving breakers only). It is not practical to have fully rated molded case breakers higher than 65kA.
I have found that on site technicians don't think twice about replacing a fuse with a different manuf/model fuse (voiding the series rating), but they are more vigilant about replacing a breaker with the same model.