Fusing Factors / Trip

[m4tty]

Fusing Factors

BS3036 - 1.8 to 2.0
BS1361 - 1.6 to 1.9
BS88 HBC - 1.25 to 1.27
MCB's up to 1.5

Then Table 7.5 OSG P58 states

B Type 3-5x In
C Type 5-10x In
D Type 10-20x In

I understand that if youve got switching surge flouescent lighting C type is favouable over B type if Zs complies as it may sometimes trip a B Type and not a C Type but im getting confused as I read MCB's fusing factor is 1.45 or is it different depending on what Type B/C/D it is.

Im confused but not very good at explaining things. If anyone gets what im saying and can explain it would be appreciated

Thanks in advance


Matty

 

[parkerbloggs]

Circuit breakers to BS 60898 B types will operate within 0.1 - 5 secs at 5 x In. The In x 1.45 fusing factor is the current the conductor can manage within the conventional time (i hour) before the protective device opens. So if a circuit is slightly overloaded for this time the cable will not be damaged .