No Overload Protection on DB wired to Busbar

[Ian1981]

That table is unlikely to be of any use as it is for a conductor operating temperature of 90C, the DB incoming terminals will almost certainly be rated for 70C operation and so the conductor operating temperature must be limited to 70C

I know it also states the correction factors for different temperature which is why I posted both

 

[davesparks]

I know it also states the correction factors for different temperature which is why I posted both

I have that same PDF and it doesn't give conductor operating temperature correction anywhere. It only gives correction for ambient temperature.

 

[Ian1981]

I have that same PDF and it doesn't give conductor operating temperature correction anywhere. It only gives correction for ambient temperature.

You are correct Dave my mistake I've misread it.
It does state that the ccc ratings given in the tables are based on 90 degrees tho.
Even the biggest panel board I've fitted with a 200amp mccb the terminals were only rated at 75 degrees max.
I've never come across anything that requires 90 degrees operating temperature.
Industrial perhaps?

 

[Flanders]

I have come across this in old factory installs a few time and in one case main fuse protecting the bus bar have been a 400amp and the same set up as the op I have always flaged these up as code 2 observations, and agree with op that fitting a switch fuse is the best option , unless there is enough room to replace the main switch with an mccb as daves says, the problem with that is you normaly nead an expansion box on the bottom of the DB to fit the mccb in , so may not be as straight forward

 

[westward10]

I know it also states the correction factors for different temperature which is why I posted both

Tri-rated cables require grouping factors the table you show is for a single conductor in free air. Four conductors together into the DB require a factor of 0.65 applied to this table.