Methods 101 - 103

[musicspark]

Looking at the BRB, at appendix 4, table 4A2 we are given different factors for the various installation methods.

For example method 103 has a factor of .5

Now looking at table 4D5 we are given different current carrying capacities for the various installation methods

EG. 8A for method 103

Should both criteria be applied? I.E. For a 1mm cable ; .5 x 8 = 4A

 

[ian3012]

in short music spark.... no.

from memory... (so i'm sure someone will shoot me down..lol)

... the method 103 downrating of 0.5 for c.c.c is an approximation which is to be applied if you're 'guessing' the job... i.e... (you don't know how long the cable run is for eg... or you don't know the thermal properties of the insulation say...)... note that it is half of the 'clipped direct' value (ref method c)

i.e. for any given cable run over 0.5 m....if clipped direct value is 24 amps, method 103 value will be 24 x 0.5 = 12 amps..

why did you want to know that lol...?? you doing 2391-20?

 

[musicspark]

in short music spark.... no.from memory... (so i'm sure someone will shoot me down..lol)

... the method 103 downrating of 0.5 for c.c.c is an approximation which is to be applied if you're 'guessing' the job... i.e... (you don't know how long the cable run is for eg... or you don't know the thermal properties of the insulation say...)... note that it is half of the 'clipped direct' value (ref method c)

i.e. for any given cable run over 0.5 m....if clipped direct value is 24 amps, method 103 value will be 24 x 0.5 = 12 amps..

why did you want to know that lol...?? you doing 2391-20?

Actually I am updating from 16th to 17th, this Friday

I just thought that this was ambiguous in BRB and needed some clarification.

My own interpretation would be to use one or the other of the two tables but it is hard to tell from the wording in the BRB whether you are supposed to apply both.

 

[ian3012]

you don't apply both... good luck with the upgrade:good luck: