I've got an issue with the new electrics in the garden office I built. Can anyone help me understand the problem? 2.5mm 3 core SWA cable feeds the office from the RCB in the house. CU in the office has 6A and 32A breakers - 6A for lighting circuit, 32A for the socket ring (4 double sockets) The armour cable comes into the box above the earth, and has yet to be connected in this photo. But then the sparky did connect it (black to earth, grey to neutral and brown to live) strange things began to happen. Firstly the socket ring tripped the house RCB without any load applied. So we disconnect the sockets either side of the CU on the ring to try to isolate. Breaker now does not trip. We start with the left hand socket and test L-N on both feeds and find one with 235V L-N. So am I right that this must be the leg which connects the socket and the CU, and that it cannot be compromised? But...nothing will work in the socket. Exactly the same happens at the socket on the right side of the CU. Why can power reach a socket, yet the socket won't power anything, including a working 3A lamp? Sparky is scratching his head, and can't explain to me what the issue is... Any help gratefully received. R
That looks a very rough installation, the armoured is not terminated correctly. Get your “sparks” back to correct the faults and test the installation, then your problems will be solved.
For a start, you need a new electrician, the main neutral is not connected, the ring circuit neutrals are incorrectly connected. And why is all that earth pvc tape wrapped around the incoming cable.
I can’t see a live busbar that connects the live output from the main switch to the live inputs to both of the MCB’s.. normally you’d see a brass metal strip that runs from the bottom screw of the live side of the main switch to the bottom screws of the MCBs
Was thinking just that - "Sparks" is my wife's uncle who thought he was doing me a favour... before I get someone in I want to try and understand the 'damage'.
A gland will also allow you to make an earth connection to the steel wire that surrounds the inner cables, gives you a better chance of the RCD tripping if cable gets damaged..
What size breaker is that lot fed from? The swa gland needs to be readily accessible so you're going to have to move that CU.
When you measure 235 volts between two conductors it doesn’t mean they are actually wired correctly and polarity is correct, a bit more testing is required to find out if they are actually wired correctly.
40A on house RCB. It is not supposed to be powering much, just 2 Led batten lights and laptop/printer/monitor etc on the sockets.
40a feeding a 32a breaker with 2.5mm is very dangerous situation. You risk an overload that could overheat the cable and start a fire. You will want to get this whole mess sorted asap. Just get a spark in to sort this out. Mostly it will want stripping out and starting again.
The MCB in the house needs to swapped for a B20 MCB, the socket ring in the office CU might as well be swapped for a B20 as well, but it’s not really needed and is little more than a switch as is just duplicating the other one in the house.
My mistake 6mm cable - but even so - I take your point that it all needs to come out and that a professional needs to come in. Thanks
It would help if you can post photos of the test certificate your “electrician” handed you. We will then be able to see what (if any) testing was carried out. Fitting a new consumer unit requires notification to the local council under building regulations, unless your “electrician” was a scheme member.
I'm no electrician but from the other posts it seems there are multiple issues so it needs taking apart and doing again. A qualified electrician can issue a certificate as well covering you for Building Regs
Sweet baby Jesus thats a mess and no mistake. that mini CU needs to come out and be re-done. some testing will isolate the fault causing it to trip, the continuity and insulation resistance of the final circuits should hve been tested before it was connected. It could be a wiring fault, or a screw through a cable, either way testing will find it. I can only assume your wife's uncle is not an electrician by trade or else he would have done a much better jonb and been able to find a fault with what must be a very small circuit! He should have completed an EIC (Electrical Installation Certificate) in which there is a page to list the results for each circuit. He should also have notified the work, either to his scheme (NICEIC, NAPIT etc etc) or direct to LABC to comply with part P - even if he hasn't done that part (in which case you, not him have broken the law, you've got to love the law, complex stuff! - I'm not a lawyer or a moral arbiter, thats your concern, as an engineer I'm just interested in the safety aspects) he should have done the EIC confirming everything is tested correctly.