16mm Tails CU 10m away domestic any advice please

[freedomrun]

Domestic 1st floor flat, TN-S, 6mm MAIN CPC, 60A Fuse. Tails at the mo are 16mm from Meter Head and run up a wall & in a loft space then down to BS3036 populated Fuse Board 60A DP switch, no RCD. I will upgrade Main CPC to 16mm anyway as I'm looking at changing this to 17th edition CU. Total length of tails are about 10m maybe 15m from Meter Head, tails seem good condition Ze is great - seeing as it's 60A Fuse, no Electric Cooker or Shower at the mo, just Immersion cct - but taking into account if these were added in future can i use the present 16mm tails (it will be quite a job to replace with 25mm tails) and are these 25mm tails ever gonna be required in a Flat really (just the distance of the tails that i'm not sure about) as i've not had this set up as yet, but expect to find many more as i progress. A bit of advice please - Many thanks.

 

[malcolmsanford]

Domestic 1st floor flat, TN-S, 6mm MAIN CPC, 60A Fuse. Tails at the mo are 16mm from Meter Head and run up a wall & in a loft space then down to BS3036 populated Fuse Board 60A DP switch, no RCD. I will upgrade Main CPC to 16mm WHY ? anyway as I'm looking at changing this to 17th edition CU.

Total length of tails are about 10m maybe 15m from Meter Head, tails seem good condition Ze is great - seeing as it's 60A Fuse Is there a separate head for this flat? Does it share a main header with say the ground floor flat?. Depending on the supply cable from the DNO and the size of their protection device you may need to fit protection to your tails.

no Electric Cooker or Shower at the mo, just Immersion cct - but taking into account if these were added in future can i use the present 16mm tails (it will be quite a job to replace with 25mm tails) and are these 25mm tails ever gonna be required in a Flat really (just the distance of the tails that i'm not sure about) The tails sizes are fine for the 60amp supply. I would be more worried about a set of tails, I'm assuming they are single double sheathed type, going up a wall and then into a loft space.

as i've not had this set up as yet, but expect to find many more as i progress. A bit of advice please - Many thanks.

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[freedomrun]

I was going to upgrade the main CPC 16mm as i thought the 6mm would'nt be suitable. Supply to the Flat has it's own head with 60A Fuse 16mm CPC to MET from Supply Clamp. At present 25mm double insulated single tails from Meter to Henley Blocks, then 16mm Tails to a 60A Fused isolator DP switch, then 16mm Tails double insulated all the way to CU maybe 10 to 15 metres away. All Tails are single double sheathed. These tail sizes are good for 60A at this length ? .... where do i find the formula / chart in the Regs for working this out, can you direct me please.

 

[malcolmsanford]

Table 4D1A for the current carrying capacity of those tails, of course you will have to check to see if you have any rating factors such as insulation, reference methods, once you determine the rating factors you can work out if the tails are OK, and then you can work out the volt drop from table 4D1B

Why wouldn't the 6mm be suitable, I'm not saying that it is, but have you done the adiabatic equation from reg 543.1.3. If it's acceptable why add more expense to the client, or eat into your profits.

So the tails do have a fused isolator, I only mentioned as you never mentioned one in your post.

 

[freedomrun]

Thats great malolmsanford, sorry forgot to mention the fused isolator, i think you are correct about the CPC - if the adiabatic equation proves it is suitable, then i can leave as is - Thanks for taking the time to respond so quickly !!