Was talking to a switchboard manufacturer and he mentioned that the switchboards manufactured to BS 61439 are only tested to 70 degrees C, so all the cables attached to/from it must be calculated for 70 degrees. The only reference in the standard which makes some sense about this is section 10.2.3.1 attached. This means that all the XLPE cabling out there which is rated at 90 degrees is under-utilised and is useless.
Many designers I assume, are not aware and proceed in producing the calculations in Amtech or similar with cables to set operate at 90 degrees and think all is ok.
MG, see Notes 1 and 2 to Tables 4E1A, 4E2A etc. (of BS 7671).
Whilst I'm sure you are correct that many will be unaware of this situation, on the flip side many people are aware of it - and it has been discussed numerous times on here (as well as text books, training courses etc). The previous (and no doubt later) replies will give a flavour as to the debate which often ensues as to how much of an "issue" it is in any given scenario.
My post isn't intended to re-open the debate, but simply to let you know that it has been covered many times ?
MG, see Notes 1 and 2 to Tables 4E1A, 4E2A etc. (of BS 7671).
Whilst I'm sure you are correct that many will be unaware of this situation, on the flip side many people are aware of it - and it has been discussed numerous times on here (as well as text books, training courses etc). The previous (and no doubt later) replies will give a flavour as to the debate which often ensues as to how much of an "issue" it is in any given scenario.
My post isn't intended to re-open the debate, but simply to let you know that it has been covered many times ?
