Temperature Class of Cable

[Ahr35181]

With reference to tables 54B to 54G of BS7671 it seems the final temperature of cable cpc’s are quite high & of possible concern in hazardous areas. For example, take an explosion-protected piece of equipment with T4 temperature classification (135degC) connected by XLPE SWA cable. During an earth fault at the equipment the design will maintain the maximum surface temp to less than 135degC, but in theory the cable armour could reach 200degC.

Any thoughts on this?

 

[Ahr35181]

I guess no one who uses this forum has come across an explosion caused by the surface temperature reached by a cable during a fault???

Alan

 

[dpc]

Try posting this in Electric Power Engineering forum. I'm not familiar with the BS standards you reference.

In the US, any circuits in a hazardous gas area must be in conduit and the conduit must be sealed.

I suspect any cable that is allowed to be exposed must be power-limited.