YES. This is the preferred method.
The wiring can be tested before anything else is done.
It can be checked visually too, and a bonding cable from the mains position to water main, gas main pipe etc etc should be confirmed first too.
Replacing Fuse Box - Is it needed?
- Thread starter House7000
- Start date
YES. This is the preferred method.
The wiring can be tested before anything else is done.
It can be checked visually too, and a bonding cable from the mains position to water main, gas main pipe etc etc should be confirmed first too.
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Before a fuse board/consumer unit swap, the correct procedure to adopt is an Electrical Installation Condition Report (ECIR)
The report will include:
*A visual inspection of the system/installation. (accessible areas only)
*Dead test: Continuity of earth and live conductors, insulation resistance and dead polarity.
*Live test: Live polarity, Ze (taken at the intake of the installation), Zs (at the furthest point of each circuit), prospective short circuit current (The current which is likely to flow in a circuit if line and neutral cables are short circuited)
RCD test (which it seems you don't have)
*Functional tests: this will generally test the mechanically operation of electrical switches and sockets and safety devices (turning things on/off)
There is a document that is filled out, that will amongst other things, highlight any non-conformities or not to current standards found, these are known as codes.
The codes used to determine whether there are non-compliances or issue with the electrical installation and are numbered C1 to C3. These codes will be entered on the Electrical Installation Condition Report, along with a description of the nature of the fault, and will determine whether a ‘Satisfactory’ or ‘Unsatisfactory’ report will be applied to the installation.
*Code C1 ‘Danger present’: There is a risk of injury and that immediate remedial action is required to remove the dangerous condition.
*Code C2 ‘Potentially dangerous condition’: Urgent remedial action required, this should declare the nature of the problem, not the remedial actions required.
*Code C3 ‘Improvement recommended’ This code more often than not implies that while the installation may not comply with the current set of regulations, complies with a previous set of regulations and so is deemed to be safe although this safety can be improved upon.
All code 1s and 2s must be rectified.
Any code 3s do not, but can be if requested.
One concern with installing an consumer unit with RCD protection to one that did not previously have this protection, is that RCDs are sensitive to earth leakage, which they will detect and if the amount of leakage is enough to activate the RCD, you will have power-loss.
So it is important that this is assessed prior to swap over.
You could also have appliances that are leaking to earth, so you may find yourself replacing or repairing, ovens, microwaves, toasters, irons, kettles, laundry appliances etc...
I very rarely come across an installation where a degree of remedial work is not required prior to a new board being installed, so be aware there will likely be some work required, it maybe that the earth conductor and bonding needs updating which is quite normal, or you could have a fault on the circuit that needs to be investigated, found and corrected (this can be a headache for both installer and occupant)
Inspection, testing and replacing the fuse board is a task that should be undertaken by a competent, qualified person. It will also require notification to building controls.
I hope this post has been helpful?
Do I take it that there is a "not" missing from that sentence?
Kind Regards, John
Correct John, thank you for proof reading and edited accordingly
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H7k - if you do have a new CU, then specifying that you want an all-RCBO one rather than one with 2 or 3 RCDs you will lessen the chances of having problems due to leaky appliances. Many things have a small amount of earth leakage current because of the nature of their power supplies, not because they are faulty. People who have a lot of TVs/DVD players/satellite boxes/set-top boxes/printers/PCs/monitors/etc can find that the combined leakage current from them is enough to cause RCDs to trip.
That's obviously a theoretical possibility but is it something which actually happens at all commonly in domestic installations? I've certainly got no personal experience of having seen or heard of it happening domestically. Those background leaks can mean that when a minor 'real' fault (not in itself enough to trip an RCD) comes along, the combination is enough to trip and RCD, but that's a bit different.
Kind Regards, John
Didn't we have somebody recently with just that issue?
3.5mA is, I believe, a typical figure for a SMPS earth leak.
So - 2 TVs, a Sky+ box, a couple of DVD players, an AV amp, a CD player, a hi-fi amp, a PC, 2 monitors, a laptop charger, a printer...
Far from an unusual number of devices, and there's 45.5mA
At 150% of In, what's a 30mA RCD supposed to do?
3.5mA is, I believe, a typical figure for a SMPS earth leak.
So - 2 TVs, a Sky+ box, a couple of DVD players, an AV amp, a CD player, a hi-fi amp, a PC, 2 monitors, a laptop charger, a printer...
Far from an unusual number of devices, and there's 45.5mA
At 150% of In, what's a 30mA RCD supposed to do?
There was certainly a case in which such was one of the speculated possible causes of RCD trips, but I don't know whether that speculation ever got promoted to actual facts.
As you say, far from an unusual number of devices, yet we don't seem to be hearing about this happening all the time - so I have to wonder about that assumed average 0f 3.5mA per device.
In my office, and off the top of my head, I usually have about 6 PCs and 4-6 monitors, 2 or 3 printers, two or three routers/network switches, several chargers (phone, camera, tablet etc.), a TV, a CD player, a radio, a couple of telephones, and often a laptop charger (and sometimes other things) all on the same RCD (which is regularly tested, properly) and the RCD has never operated in very many years (other than during testing
) - and I reckon that's probably far more than one would see in most domestic situations. So, again, my loads cannot possibly be averaging as much as 3.5mA leak each.Kind Regards, John
When I still lived at home I experienced such an issue.
Picture a house with three late teens/early twenty some-things living there. We all had a PC and TV, there was a server as well, A sibling would occasionly have friends bring PCs over either for repair, or to play computer games. The RCD would trip out quite often.
I ended up having to change the board to all RCBOs when my father was late for work when the alarm clock didn't go off because the RCD had tripped in the night and didn't get reset until morning
Picture a house with three late teens/early twenty some-things living there. We all had a PC and TV, there was a server as well, A sibling would occasionly have friends bring PCs over either for repair, or to play computer games. The RCD would trip out quite often.
I ended up having to change the board to all RCBOs when my father was late for work when the alarm clock didn't go off because the RCD had tripped in the night and didn't get reset until morning
As I said, it clearly is a theoretical possibility. However, as I also said, I think it must be pretty rare, since we would otherwise be experiencing and/or hearing about it fairly often, which doesn't seem to be the case.
Kind Regards, John
I'd really rather not.
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