I presume you mean terminal screw temperature - not ambient air - as most MCBs are rated to a max ambient of 60C or even 55 in certain cases.

I fear you will draw a blank, as it it something I spent some time looking into a while ago, but if you ever do get a clear statement from some make I'd be most interested.

Meanwhile if you are asking so you can use the 90C rating of a multi core cable, I may be able to offer some anecdotal reassurance. Once the cable is unbundled into single insulated wires, so long as there is a reasonable opened out length, and cores are sensibly spread and looped, before they enter the terminal, the singles are much better cooled than the multicore, and the temperature at the terminal is considerably cooler than the cores of the cables.

The problem is that the extra cooling is quite dependent on uncertain things like the amount of free air that can convent in the enclosure, and what else is in there sweating away... We make use of maximum indicating temperature stickers in some cases as a reassurance, and also as a warranty diagnostic, and it is very rare that things are hotter than we expect, unless something has been horribly abused.

Mike.

I presume you mean terminal screw temperature - not ambient air - as most MCBs are rated to a max ambient of 60C or even 55 in certain cases.

I fear you will draw a blank, as it it something I spent some time looking into a while ago, but if you ever do get a clear statement from some make I'd be most interested.

Meanwhile if you are asking so you can use the 90C rating of a multi core cable, I may be able to offer some anecdotal reassurance. Once the cable is unbundled into single insulated wires, so long as there is a reasonable opened out length, and cores are sensibly spread and looped, before they enter the terminal, the singles are much better cooled than the multicore, and the temperature at the terminal is considerably cooler than the cores of the cables.

The problem is that the extra cooling is quite dependent on uncertain things like the amount of free air that can convent in the enclosure, and what else is in there sweating away... We make use of maximum indicating temperature stickers in some cases as a reassurance, and also as a warranty diagnostic, and it is very rare that things are hotter than we expect, unless something has been horribly abused.

Mike.