New cu first or plaster bare wall?

[Richard Renshaw]

Hi. Hoping this is an easy question for someone who knows stuff!

Currently have an old wylex fuse box which I want to have replaced.

It's on a bare brick wall in the entry which is pretty much sitting on the Meter on the outside wall.

I also want to plaster the room as it's bare brick and move the cu higher up away from little hands.

What should be first? Any complications? Will rewiring be needed. Don't get blown fuses so think existing wiring is OK!

Appreciate any info you can provide.

 

[phatboy]

Rewiring will depend if cables go up or down from the current fuse box. If they go up, then no major issues.

If you can remove the old board then I would plaster the area. If not, then get the new consumer unit all installed (Can chase the cables into the wall above before skimming), and then fit stop beads around the CU and plaster up to that.

Do you plan to hide it all in a cupboard or similar?

Alternatively the new consumer unit could be fitted onto a ply board, then skim up to that....

 

[PrenticeBoyofDerry]

Ask the electrician that is undertaking the work and signing/notifying the work off, their advice.

 

[AndyPRK]

cu first for Me.

But tell them and plan out what's happening.

Maybe add capping over cables.

 

[Iggifer]

Gotta be CU first if it's moving. As has been mentioned though, either fix it to some ply, stand it off the wall or use stop beads.

When you come to change a CU that has literally been plastered into the wall, it can get messy.

 

[Taylortwocities]

Will rewiring be needed. Don't get blown fuses so think existing wiring is OK!

The fact that no fuses blow is not a criterea for whether rewiring is needed. This can be determined by having an EICR (Electrical Installation Condition Report) done for your installation.
Tests are carried out on all of the circuits together with a visual inspection. This will determine if there are any inherent problems with your cabling and that the infrastructure is likely to be serviceable for some time to come.
Old and faulty cabling can have faults that will not cause a fuse to blow, but may cause today's safety devices (RCDs and the like) to trip. Also interconnections between separate circuits can cause similar problems.
An EICR will identify these before the fuseboard is removed.

A competent electrician should be carrying out tests and checks on an installation before a fuseboard is replaced.

 

[JohnW2]

.... but may cause today's safety devices (RCDs and the like) to trip. Also interconnections between separate circuits can cause similar problems. An EICR will identify these before the fuseboard is removed.

As a matter of interest, I wonder what tests or inspections done in the name of an EICR would detect all the 'interconnections' that matter?

I ask because I recently saw a case in which an EICR was (apart from a few minor things) pretty 'clean' but noted the absence of RCD protection, and recommended that this should be addressed, effectively requiring that the 8-way Wylex Standard be replaced. That was agreed to, and it was only when a new dual-RCD CU was installed that all the borrowed neutrals on the lighting circuits showed themselves.

When undertaking an EICR on such an installation (assuming it had more than one lighting circuit) would you routinely check every light to ascertain which neutral it was using?

Kind Regards, John

 

[PrenticeBoyofDerry]

As a matter of interest, I wonder what tests or inspections done in the name of an EICR would detect all the 'interconnections' that matter?

I IR between the neutrals (neutral-neutral) and lives (live-live) of each circuit not just the neutral and live of individual circuits, to eliminate the shared/borrowed neutral aspect, but in conclusion this would not always pick up everything.

Regrettably, by the evidence given by the OP (so far), we have nothing to say that this work, is to be carried out by someone with a knowledge of testing! Or that it is to be done legally! Could be a DIY SOS in the making?

 

[Taylortwocities]

As you know. EICRs, by their nature, are under restrictions limiting their scope to detect absolutely everything. There is time pressure, as the installation is without power for extended periods. There is fiscal pressure, otherwise the inspection and test could be very expensive indeed. There are practical issues as the wiring is mostly hidden.

My post was meant to underline to the OP that him thinking the wiring is OK (because the fuses do not blow) is not a guarantee of any sort!

 

[JohnW2]

I IR between the neutrals (neutral-neutral) and lives (live-live) of each circuit not just the neutral and live of individual circuits, to eliminate the shared/borrowed neutral aspect, but in conclusion this would not always pick up everything.

Thanks. Yes, I think that the only way to do it is to literally test for connections/continuity between the neutrals (and lines) of each circuit, but I was wondering whether that is usually done routinely in the context of an EICR, since I don't recall (maybe have have just forgotten!) having seen it talked about in 'testing guides' etc. - and the standard EICR paperwork does not seem to have provision for recording the results of such tests.

You've said that you would do it, but do you think that electricians in general would do it routinely as part of an EICR?

When you say that you test N-N and L-L between circuits, do you only do this for lighting circuits, or for all circuits? If the latter, it could be pretty tedious and time-consuming. For example, with an 8-way board, there would be 28 N-N pairs and 28 L-L pairs to test - a total of 56 tests!

Kind Regards, John

 

[JohnW2]

As you know. EICRs, by their nature, are under restrictions limiting their scope to detect absolutely everything. There is time pressure, as the installation is without power for extended periods. There is fiscal pressure, otherwise the inspection and test could be very expensive indeed. There are practical issues as the wiring is mostly hidden.

Indeed, I understand and accept all that. However, given that you had written "An EICR will identify these before the fuseboard is removed.", I wondered (for my education!) whether I was missing some quick/easy way to check for 'shared neutrals' etc., and whether such tests are routinely undertaken during an EICR. As I've just written to PBoD, to literally test for all the possible N-N and L-L connections between circuits could be a very time-consuming exercise!

My post was meant to underline to the OP that him thinking the wiring is OK (because the fuses do not blow) is not a guarantee of any sort!

Sure, and I obviously totally agree with that.

Kind Regards, John

 

[flameport]

There is no particular quick way to test an entire installation for shared neutrals, however for the vast majority of them it will be the lighting circuits, and the easiest option there is to remove the switch in the hall and landing and see what wiring arrangement is used.

 

[Taylortwocities]

We are talking about installations of "a certain age". With these, one is often faced with lighting circuits centred on one or two multi junction spaghetti boxes. Usually buried somewhere in the loft and under the carpeted landing.
You're unlikely to include that in your EICR timetable.

I agree, it's never easy.

 

[JohnW2]

There is no particular quick way to test an entire installation for shared neutrals, ...

That was my point, but I wanted to be sure that I hadn't missed some easy/quick way!

however for the vast majority of them it will be the lighting circuits ...

Indeed, which is why I suggested/implied that perhaps one 'need' only test for shared neutrals in lighting circuits (and then, obviously, only if there is more than one such circuit).

... and the easiest option there is to remove the switch in the hall and landing and see what wiring arrangement is used.

That wouldn't have been 'an option', let alone 'the easiest option', in my house as I found it nearly 30 years ago. Virtually all of the light switches had just a single cable (without CPC) connected to them, most of which cables went to a spaghetti-like JB (per TTC comment), usually in some accessible place! Looking at the 'wiring arrangement' at the switch would therefore have given no insight into how the circuit was actually wired!

Kind Regards, John

 

[Iggifer]

There's a rough as F and potentially dangerous method to check for borrowed neutrals, more than borrowed lines. Shan't be sharing it publicly. Not a guaranteed method but can give an indication.