tails from meter box to consumer unit

[kibeth]

i need to run 35 mm tails from meter box to new consumer unit which is now going in the garage(pme).Its about 8m away and the only route available is through the first floor joists down a new pitched roof (inside )and then down to the meter box.Now the easiest way would be down the cavity and straight into the box,or has any of you got any sugestions,maybe i should use swa,

 

[comms]

meter - 25mm tails - switchfuse(kmf) - 8 meters of SWA - new cu

 

[comms]

meter - 25mm tails - switchfuse(kmf) - 8 meters of SWA - new cu

Forgot to say , stay out of the cavity