I posted this pic in a different thread. Long story short was called out to a loss of power and found this which had been overloaded and decided to start melting, resulting in the damage you see to the board here as well as a melted RCD and MCB
So at the time I made a temporary fix to restore some power for them but made it clear the board needed changing. Much discussion then ensued as I point blank refused to change it without doing a full EICR to establish the condition of the electrical installation and ascertain why that had suffered that damage. When I made the temp fix the tests I did said the cabling etc was intact so something else was amiss. I had my suspicions that the circuit was just pulling way too much and the 40A MCB had finally been cooked, in turn causing an issue for the 63A RCD.
Any went back today to do the EICR as I'll be changing the board in a few days. I found out the reason why this had happened fairly quickly.
The main, melted DB, fed the following:
3 x 6A Light circuits
1 x 3A Smoke detector circuit (shows the age as it was a 3A 60898 which I haven't seen before)
2 x 32A ring circuits
1 x 40A cooker circuit
1 x 32A shower circuit
1 x 16A immersion heater circuit
1 x 40A circuit to feed a sub main.
Sub main 1 fed by 16mm T&E (which is hanging off the 40A circuit)
1 x 6A light circuit
1 x 40A shower circuit
2 x 32A socket circuits
1 x 16A Immersion heater circuit
1 x 32A sub main in a garage
Sub main 2 fed by 16mm 2 core XPLE & a 10mm CPC (which is still hanging off the 40A circuit in main DB)
1 x 6A light circuit
1 x 32A socket circuit
1 x C16A circuit for a welder
1 x C16A circuit for a compressor
1 x C16A circuit for a table saw
This used to be two properties which has been knocked into one. Sub Main 1 was the original main supply for the second house and still has the cutout next to it. But it has been disabled and meter removed.
I also have never seen a neutral fly lead like this from the RCBO!
So another discussion has now ensued as I've walked off the job for now.
I told the client they had three options:
1. Get the DNO/Meter company to reinstate that cutout and have two supplies/bills
2. Get the DNO to upgrade to a 3 phase supply
3. I can remove the circuit for the sub mains out of the main CU, put in a henley block to split the tails. Run a set to the new main DB and then run a set to 63A fused isolator. From the isolator I would then run the supply to the sub mains but they were under no illusion this was a sub optimal solution and would still require careful management of electric use as they could still blow the main cutout but hopefully the isolator would trip first.
I also found this, which they were still using
So I've updated the quote to include option 3 as that's the only way I'm changing the board for them now.
There's a fair few other issues too. But most I can resolve in one go.
What beggars belief is that someone thought it was a good idea to run those two sub mains from a 40A MCB in the first place!
mg_smile:
