Main switch

[hodaire]

looking at changing a CU, next to the one i am changing there is a 2nd CU via a timeswitch for storage heaters, so at the minute there are 2 main switches - is this allowed? can i just change the CU and ignor the second one?

 

[ajelec10]

Any electrical installation has to have a single point of isolation (main switch) this is commonly overlooked in domestic installations where additional consumer units are added, my advice would be to install one. and then go to your 'phase blocks' wylex do a nice switch but can't remember exactly what its called.

Hope this helps

AJ

 

[hodaire]

problem i have is the phase blocks are fed from the timeswitch, looks like the only way to add a main switch would be on the cable between the meter and the time switch so i can't be doing this myself. would the supplier be able to provide a main switch for this type of situation

 

[NoSparks]

Your quite right, stricktly speeking a master switch is a requirement, but it is widely recognised that multiple CUs may be connected via a phase block. I just spent 10 mins typing an story about my inspector on this question but lost it when I hit the wrong post button! Suffice it to say the NIC will not normally fail an installation like yours.

I think in your last post you meant the phase blocks are fed from the meter. How do you intend isolating the CU while you change it? You could remove the CU tails from the phase block live, but this is contrary to the Safety at Work Act, and dangerious to your health. The alternative, though illegal, is to remove the distributers cut out. In that case, if you really wanted to you could then remove the meter tails from the phase block and put them in a master switch, then put new tails from the switch back to the phase block. I now re-seal the cutout with a tamper proof seal from the NIC. You will not find any other reference to doing this but it does tell the distributor the person who removed it was a qualified electrician.

 

[hodaire]

to fit the switch myself i would also need to cut the seals on the meter and the timeswitch because of the way its wired, so prefer to get the supplier involved in fitting this.

this job will be inspected by the nic so need to make sure its right. is it possible to say the supplier is booked to come in and fit a switch or am i likely to have a problem on the inspection.

 

[NoSparks]

To be honest, as I tried to indicate above, I wouldn't bother. (Indeed I will not bother on tomorrow's job where I have the same situation). Just please don't remove the meter tails from the phase block without first withdrawing the cutout.

 

[hodaire]

just had an nic inspection for domestic installer, showed him the job as it is and he didn't even mention it, i had left some tails and a main switch near to the cu and had some blag ready just incase but didn't need it, happy days