MAster12
Member
- Location
- Boston, MA, US
I am sizing the primary side overcurrent protection for a 75KVA step-down transformer 480-120/208
Table 450.3(B) provides the MAXIMUM rating of overcurrent protection on the primary side as being 125%. Does this mean the overcurrent protection can be rated less.
Is a transformer considered a continuous load?
75,000/480/1.732 = 90A - Can I use a 100A breaker/fuse as my primary side protection or does the code require 125% - 90A x 1.25 = 113A (125A next size up)
I know... very basic question
Table 450.3(B) provides the MAXIMUM rating of overcurrent protection on the primary side as being 125%. Does this mean the overcurrent protection can be rated less.
Is a transformer considered a continuous load?
75,000/480/1.732 = 90A - Can I use a 100A breaker/fuse as my primary side protection or does the code require 125% - 90A x 1.25 = 113A (125A next size up)
I know... very basic question