1.5mm T+E cable loading

[johnmadbag]

I have a question,about cable loadings, just to satisfy my own curiousity. The background detail is a bit long, apologies. If you get bored easily, probably stop now.

I went to help a friend out who had a trailing cable in the utility area of their one bedroom flat, and also wanted a like for like immersion timer replacement. The area has the immersion and cylinder, shower pump, and washing machine. The cable was from the shower pump to an old switch marked water heater. The immersion (3kw) was wired into the final ring for the kitchen. So I determined the switch marked water heater was a radial back to the c/u and a 6A MCB

I moved some cables aroud to wire the pump through an FCU into the kitchen final ring, wired the immersion to the radial through a 20A DP switch, left the 6A MCB off, and my friend called an electrician to fit a new 16A MCB on the radial. I wasn't available to discuss when he visited, but apparently he refused to fit the MCB on the grounds it was a 1.5mm T+E and so he then rewired it all back the way it was. There is now a loose cable trailing round the front of the water cylinder, and the immersion, oven, washing m/c, dishwasher etc all on the 32A final ring. He said the 32A may flip, but just reset it.

My understanding is a 3KW heater will draw about 12.5A, depending on voltage, and the lower limit for 1.5mm T+E is 14.5A, up to 20A when clipped. This cable goes directly into loft, under insulation, down cavity wall to switch. about 2M in loft, so 4M run max.

So. Is it OK to use 1.5mm T+E in this case, or should I run a new cable and get him back? Or can I leave it as it is?

Thanks for reading

John

 

[littlespark]

2.5 would be better, especially if covered in insulation.

Basically, the heat generated in the cable cannot dissipate, and the current carrying capacity of the cable goes down.

Good practice to have any load over 2kW on its own circuit