Confirming system and install

[ericmark]

It is worrying that people who are acting in the role of "tradesperson" are asking for advice on a DIY forum.

Why? I am an electrical engineer on paper, but still asked on here about type AC, and type A RCD's. Some times you simply want some one to bounce ideas with to help one understand what is really required, we are told you write out a method statement and from that you do a risk assessment, but with a house hold we can't really write out that method statement, so we have to try and consider the scenarios, and what would happen with each scenario and try and design the system to suit all you have thought about.

In University we were told you have a conveyor belt which can have a plastic lion, hippo or kangaroo, design a program that puts each in it's own cage, we thought about sidewards, backwards etc, and all seemed to work, then the school children arrived, we had never considered the lion would ride on the hippo.

And this is the problem, we can miss a scenario, so bouncing ideas can help ensure you have not missed one. Like for example pulling the DNO fuse with a smart meter the suppliers knows some thing is wrong.

 

[ericmark]

Just read what you have said, had similar problem with mothers house, old Wilex fuse box, was replaced with a CU before RCD protection was required for all circuits and the RCD for many circuits had to be replaced with an isolator due to faults on the installation, not by me, so I told him needed a rewire, his answer was not in my life time I am fed up with living in a building site, you can do it when I'm dead, which is what happened.

However I was left with a new kitchen being fitted and finding a way to power the kitchen without a full rewire.

This is what makes life interesting, I used a second consumer unit supplied from the largest MCB I could find to fit the board.

In your case clearly a problem as you need RCD protection, however some times you simply need to say no. My son at one time worked as a sole trader, and he had on multiple times problems with the DNO, they would agree a time then phone up the client and say arriving early or late and I would be asked my my son to attend, and some times silly statements, like you are suppose to put a duct in here for our cables, answer was sorry in 1564 when this mill was built the builder did not envisage that requirement.

So likely you can fit a second CU fed from the first one, or fit an isolator and get the DNO to move the supply to the isolator, but the phone call "DNO have been and moved the supply, we now have no lights or freezer supply when will you get here?" has to be expected, it happens.

With 10 years experience going as a sole trader is OK, but with 6 months experience it does not really work, unless your very selective in what work you take on. My son only got away with it because he had a father, and two grand fathers in the same trade.

 

[bernardgreen]

Obviously tradespeople will have gaps in their knowledge, but filling those gaps by asking on a DIY forum could result in the gap being filled with dangerously in-accurate "knowledge".

No one so far has mention the significant risk of the fuse holder in that cut out falling apart when the fuse is pulled.

And this is the problem, we can miss a scenario, so bouncing ideas can help ensure you have not missed one.

Yes I agree, sometimes a problem doesn't need to be solved but instead can be turned into a benefit (*).

(*) A numeric only input terminal working over a modem link had to be modified to accept a full alpha-numeric keyboard and display without altering the main board. All TTL logic, no processor in the the terminal. It was just possible to achieve this but when the routine ( every 5 minute ) comms check occurred the last two places in the display flashed a random pair of charactors. There was no way to avoid this without a major change to the main board. The benefit was achieved by writing OK to those charactors as part of the comms check. The operators found the flash of OK as a re-assuring sign of system integrity

 

[sparkwright]

Can you describe what can happen if the fuse holder should fall apart, I can't fully imagine it without seeing one.

 

[ericmark]

I bet you have a plaque on your desk saying "These people who think they know it all, are specially annoying to those of us that do."?

 

[bernardgreen]

what can happen if the fuse holder should fall apart,

The incoming Live lead makes contact something Earthed ( metal cutout case ) or the Neutral bar. With a 200 ( or maybe 400 ) amp fuse at the substation the arc formed is quite spectacular.

 

[SUNRAY]

In a taped up connector block behind the board most likely .

I hope not into the same single connector as the matching black and the earth.

 

[SUNRAY]

The incoming Live lead makes contact something Earthed ( metal cutout case ) or the Neutral bar. With a 200 ( or maybe 400 ) amp fuse at the substation the arc formed is quite spectacular.

Or in more than one sub I've seen inside of - 2000A!!!

 

[bernardgreen]

Or in my street 2000A!!!

That is just being greedy

 

[sparkwright]

I hope not into the same single connector as the matching black and the earth.

Could it be a feed to the house next door perhaps?

 

[SUNRAY]

Could it be a feed to the house next door perhaps?

It can be so many things: remains of E7, streetlight, landlords feed...