Type 1,2,3,4 Vs B,C,D?

12 Dec 2004
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United Kingdom
Calling all older and wiser sparks. Sorry I know this has probably been asked before, but did a search and found nothing.
Could someone please tell this fledgling the differences between the old obsolete breakers, and the shiny, new B,C,D's.
Am I right in believing that 1-4's trip nearer to their In than B-D's?
Any more info about the general characteristics of Type 1-4's would be absolutely spiffing dear fellows.
Also if anybody could dig out their 15Th Edition (circa 1923 :) ) and post maximum Zs for these antiquated breakers, would be hugely appreciated.
Cheers, TS.
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29 Sep 2003
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West Midlands
United Kingdom
Instantaneous trip currents are as follows (60898 breakers included for comparison)

Type 1 = 2.7 to 4 x rating
Type B = 3 to 5 x rating
Type 2 = 4 to 7 x rating
Type C = 5 to 10 x rating
Type 3 = 7 to 10 x rating
Type D = 10 to 25 x rating
Type 4 = 10 to 50 x rating

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