XLPE 90 deg

[RobFurn]

XLPE allows for a higher current capacity due to its XLPE insulation, the by product of which is an increased conductor temperature at full load. Right.
Say if I am running a sub main off a 63A breaker and its running at full load the regs state that I must use an accessory that can take the increased temperature 512-02-01. whats the crack with standard MCBs will they take temperatures up to 90 deg. Or do I have to use a special MCB (same thing with the isolator at the sub)

 

[Adam_151]

Ask the maker of the device/look in the datasheets

Or just use the figures from the PVC SWA table and go up a cable size

 

[RobFurn]

Or just use the figures from the PVC SWA table and go up a cable size[/quote]

I knew somone would say that. Thats obvious (but thankyou Adam) My point is whats the point of XLPE if you cant connect it to an accessory to take advantage of its additional Current rating.

 

[RF Lighting]

Its designed for industrial use, where many of the accesories such as busbars will happily run at 90 degrees.

 

[ricicle]

Yeah, copper melts at 1084 deg C

 

[RobFurn]

Its designed for industrial use, where many of the accesories such as busbars will happily run at 90 degrees.

So your saying Its bad practice to use the current rating of XLPE when working out calcs as its not designed for "domestic " use just big stuff?

Better to use the tabulated "PVC" 70deg tables?????????????

 

[RF Lighting]

If whatever you are terminating the cable into is designed to withstand 90 degrees then use the XLPE/SWA current ratings, if not use the PVC/SWA ratings.

 

[RobFurn]

I have run a sub main from the main CU into a Kitchen. Now the client wants provision for an electric cooker 40A. Told me this after I have run the cable hooray! probelm Is I ony ran 10mm sq even if I apply diversity its tight as the CU in the kitchen also supplys a garage. So I was thinking Ahaaa its XLPE 30% more current rating but NOW Im thinking the standard MCB from the main CU wont handle 90deg rignt?