New consumer unit and shower feed

[JOHNBOY42]

Guys/gals, a couple of months ago I posted a topic about my shower having a burnt out fuse and was rightly advised by the replys to pull the fuse which I did,since then I have run a temp feed from the taps to a shower head ,,,,,,,one of those cheap flexi hoses,anyway had to put up with that as my finances was stretched in other areas.I now have some finances too update.
I have the old wired fuse box with 3 fuses in and the 4th one pulled which was the shower unit which I wish to upgrade to the circuit breaker type but as I am not qualified will call a sparky in, the shower cable also appeared melted in the loft when I was up there so I will run a new cable ready for the spark to wire up,the shower was there when I moved in and it is a faily new triton jade but I could not find the kilowatt ,now my questions are what size cable will I need to run in ,it as about 3 m in boxed in area covering pipes/cables 2m under floorboards and 4m in loft space,will a 10mm be ample if its 9.5k or 8.5k and is there anything else I will require,also I am upgrading the old consumer unit is this a expensive job????? and I dont suppose I could help here

 

[davy_owen_88]

what size cable will I need to run in ,it as about 3 m in boxed in area covering pipes/cables 2m under floorboards and 4m in loft space

Are the pipes in the boxed in area for central heating? If so you'll need to consider the increased ambient temperature. Make sure you keep the cable well clear of any loft insulation and clip it to joists/rafters for as much of the run as possible to aid heat dissipation.

will a 10mm be ample if its 9.5k or 8.5k

10mm² is good for 64A before derating, so you should be ok unless the cable runs through very undesirable conditions.

is there anything else I will require

Check on the condition of the isolator switch and replace if necessary.

also I am upgrading the old consumer unit is this a expensive job????? and I dont suppose I could help here

It could become expensive. This is a reply to another thread earlier on tonight:

Well before you change a CU you have to ensure the installation meets certain standards - continuity of protective conductors and ring circuits, insulation resistance, earth fault loop impedance, etc. etc..

You must ensure the meter tails, main bonding/main earthing conductors are appropriately sized, and that you have the correct RCD arrangement for your earthing method (TT requires a S-type RCD protecting the whole board, with 30mA protection for socket outlets likely to supply outdoor appliances, showers and circuits within certain zones within a bathroom). You must also confirm RCD operation and disconnection times during faults.

So if your installation requires a lot of updating then that will bump the cost up, but if it is in pretty good nick it shouldn't cost too much.

 

[didthathurt]

so I will run a new cable ready for the spark to wire up,

Check first as he won't necessarily sign off the work if he has not been involved from the start. When running a new cable like this, he/she will also want to determine why the original melted and if the supp bonding is up to spec at the same time.