Rewiring plan

[JohnW2]

I like the idea of using radials and running some extra earth cable to make the earth into a ring for added safety ....

You're obviously free to do that and, as you say, it would afford "added safety", but I presume you understand that it is an 'additional safety feature' which people almost never bother to include in 'normal' installations.

Kind Regards, John

 

[Risteard]

the radial final circuit is what I would term "failsafe".

Not with a broken cpc...

 

[VogonPoet]

You're obviously free to do that and, as you say, it would afford "added safety", but I presume you understand that it is an 'additional safety feature' which people almost never bother to include in 'normal' installations.

Kind Regards, John

Understood John, thanks.

I've now spoken to my local Building Control department again and they have assured me that their Building Notice charge for a rewire (around £360) includes all the fees required to get sign-off and that I would not need to pay any third parties as part of the process. Their charge includes all necessary inspections. I made it clear that it was a DIY job, that I was not an electrician and I could not certify any of the installation myself.

He said that they do not inspect the work themselves, they will contract out the job to a separate firm and that the firm will tell me what needs inspecting and testing when. He did say that they had never received a Building Notice for a DIY rewire job before so I would be something of a test case - their procedures and charges for the service might end up changing as a result.

So it looks like it is a flat fee, at least in this instance. That said I obviously don't want to be calling them every other day to inspect or test things so I'm going to try to split the process into a small number of stages.

I'm fortunate in that I'm not going to be re-using many of the existing wall chases/runs for sockets. There aren't that many to start off with, and most of the ones that are there happen to be in inconvenient places. I think this will mean that I can leave much of the existing installation in place while I fit the new stuff. I've also pulled the ceiling down in much of downstairs so access for running cables through joists (and inspection) is great.

I've contacted my electricity supply company (EDF) and they have agreed to install an isolation switch between the meter and my existing CU free of charge, so I will be able to switch of the supply to everything on my side when necessary. I had planned to move the location of my CU anyway so it occurs to me that the best way to proceed might be to install the new CU in it's final position and have it running at the same time as the old one during the rewire.

The old CU is on a board in the under stairs cupboard at around waist height, the incoming supply and meter is directly on the other side of the wall from it (on an outside wall of the house and accessed via one of those white meter cupboards). It seems that the existing meter tails feed directly into the back of the old CU.

I'd like the new CU in a position up and across a bit on the same wall so it is roughly at eye level just as you enter the cupboard. That'd mean the new tails would be around 1 meter long and would run in surface mounted conduit once they enter the inside of the house - is that ok regs wise?

 

[Risteard]

Currently, some people install dedicated freezer circuits without RCD protection (to avoid the risk of 'nuisance trips' whilst they are on holiday. When the new reg appears, unless one hard-wires the freezer (so that there is no plug/socket involved) even a dedicated ('one socket') circuit will have to be RCD protected.

So what is the issue? If a dedicated RCD is used for that circuit (either an SRCD if cable installation methods permit), an RCBO or an RCCB serving only that circuit in conjunction with a circuit breaker/fuse then you are only going to lose the contents of your fridge/freezer if there is a fault with the fridge/freezer. There really isn't any justification for avoiding RCD protection to these - the only potential issue is with a shared RCD and not a dedicated one.

 

[securespark]

Not with a broken cpc...

Sure.

No circuit is "failsafe" in that respect. I was talking about continuity of the other two: if they come apart on a ring final, there a problem and you don't know about it, if they come apart on a radial final, the supply is interrupted and the problem apparent straight away.

 

[JohnW2]

Understood John, thanks. .... I've now spoken to my local Building Control department again and they have assured me that their Building Notice charge for a rewire (around £360) includes all the fees required to get sign-off and that I would not need to pay any third parties as part of the process. Their charge includes all necessary inspections. I made it clear that it was a DIY job, that I was not an electrician and I could not certify any of the installation myself.

That sounds pretty similar to my LABC - as you say, it's a 'flat fee', seemingly with no 'extras'!

Kind Regards, John

 

[JohnW2]

So what is the issue? If a dedicated RCD is used for that circuit (either an SRCD if cable installation methods permit), an RCBO or an RCCB serving only that circuit in conjunction with a circuit breaker/fuse then you are only going to lose the contents of your fridge/freezer if there is a fault with the fridge/freezer.

Those who are concerned about such things (not me!) are seeming worried about (amongst other things) 'nuisance trips' of the RCD/whatever, in the absence of any fault in the freezer. Some people seem to suffer quite a bit from such trips, although I have to say that, in many years of living with many RCDs (about 11 at the last count), I don't think I've ever experienced one tripping 'without good reason'. Indeed, I've heard of some people wiring a dedicated freezer circuit in SWA or other cable with an earthed sheath, specifically in order to avoid the need for RCD protection of a buried cable.

There really isn't any justification for avoiding RCD protection to these - the only potential issue is with a shared RCD and not a dedicated one.

See above.

Kind Regards, John

 

[ban-all-sheds]

What's going on?

The OP wrote this:

I would be something of a test case

But the word "test" has been turned into a link which doesn't work

 

[ban-all-sheds]

Those who are concerned about such things (not me!) are seeming worried about (amongst other things) 'nuisance trips' of the RCD/whatever, in the absence of any fault in the freezer. Some people seem to suffer quite a bit from such trips, although I have to say that, in many years of living with many RCDs (about 11 at the last count), I don't think I've ever experienced one tripping 'without good reason'.

I have heard that with a 2-wire overhead TT supply VOELCBs can be tripped by nearby lightning strikes.

Whether that is the source of all the fears of RCDs tripping while people are away IHNI.

 

[JohnW2]

I have heard that with a 2-wire overhead TT supply VOELCBs can be tripped by nearby lightning strikes.

Possibly, although one imagines that there are few such devices still in service.

However, it's not just VOELCBs, and I forgot this when I said that I hadn't experienced 'nuisance' RCD trips. Although the last 50m or so of my supply is still (4-wire) overhead, for the last 15-20 years most of the rest of my village's supply has been underground. Prior to that, the entire village supply was overhead and, in those days, lightning within a few miles sometimes caused RCD trips. Since most of the local network moved underground that seems to have stopped, and it remains the case that I have experienced few, if any, 'nuisance trips' in the ensuing 15-20 years. Maybe that gives a clue to at least one mechanism whereby some people seem to suffer quite a lot of ('unexplained') 'nuisance trips'?

Kind Regards, John

 

[John D v2.0]

But the word "test" has been turned into a link which doesn't work

Same for the word system last week, and apparently admin are looking into it, so maybe they just renamed it somehow.