Inspection recommends new CU....

Our old house, which is to be rented, has had its first electrical inspection. One of the things they are saying is that the CU needs to be replaced, to meet the 17th edition......

The existing one has MCBs, not fuse wire, and RCD protection, and is not faulty so they say. So, in layman's terms, why might a CU need to be ripped out and replaced?

I know there might be a zillion reasons but there is nothing else in the report to suggest why a new CU might be needed.

TIA

It may well be true that it needs replacing to meet 17th requirements but -

you don't need to meet 17th requirements.

It doesnt.

It might not meet current regulations but theres no requirement to bring older installations up to standard.

Is the whole board RCD protected?

Just check what your insurer requires (and find a different one if they insist on an unnecessary upgrade).

Thank you. Its not the insurer that is pushing it....the letting agent organised the inspection.

Here is the summary of the report. Sure, there's stuff that must be needed but they are quoting a total of over 2K to sort it all out, so I need to see why I am forking out on all that work!


As a landlord the government web site makes it clear that safety must be ensured, not that some certificate is needed. How much of what's on there is a safety issue, in your opinions? I really dont want to sidestep my responsibilities but I am also wary of work that MIGHT not need doing.

What arrangement of protective devices do you have in your CU (if you are unsure post a photo, we can most likely work it out from there). Also what make and model is the CU? (again pictures very helpful.

The main reasons to replace a CU are
1: it's unable to accomodate the arrangement of protective devices that you require
2: it is from an obsolete range and parts are either unavailable or prohibitively expensive.
3: You are in a hurry and it's quicker to replace the whole thing with something the electrician has in stock than to source parts for the existing CU.

The opinions on what is and isn't an acceptable arrangement of protective devices have shifted over the years.

Back when RCDs first came in it was common to put the whole house on one RCD. The trouble with this is that it means in the event of a fault you can lose all power in the house and you may need to open up the CU and disconnect circuits to get it back (merely turning off the MCB is not always sufficient due to the fact MCBs are single pole devices and a neutral to earth fault can trip a RCD)

So this arrangement fell out of favour. At the time only "sockets that can reasonablly be expected to supply equipment outside of the equipotential zone" actually had to be RCD protected so it was common to see "split load" boards. At the higher end one saw RCBOs which provided RCD protection to individual circuits.

Then the 17th edition came along which required most normal domestic circuits* to have RCD protection. Single RCD setups were still out of favor so this resulted in the norm for low end installations becoming the dual RCD split board where the circuits are spread across two RCDs. High end installations continued to use RCBOs.

The regs themselves are pretty vauge on the subject of how many RCDs an installation needs to be split over, they just say that instalaltions should be devided into circuits to prevent injury and minimise inconviniance. It's widely accepted that putting all circuits on a single RCD does not comply with this. I'm personally not convinced that splitting the circuits over only two RCDs really complies either but it seems to be accepted by the powers that be.

Also afaict while an EICR tells you where your installation stands relative to current regs you are not under any obligation to upgrade it to meet them.

* All socket outlets for general use and rated less than 20A require RCD protection. So do all circuits with concealed cable that does not have an earthed metal layer, is less than 50mm deep and is not part of an installation under the control of a skilled or instructed person. So do all supplies to bathrooms. Most domestic circuits will fall under at least one of these unless they have been specifically constructed to avoid it.

I am not living there any more and dont have a picture sorry. I appreciate the efforts in your reply.

Aragorn84 said:

It doesnt.

It might not meet current regulations but theres no requirement to bring older installations up to standard.

Is the whole board RCD protected?

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Yes, if understand you. Sorry I dont have a pic as I dont live there any more but there is an RCD switch (which trips the whole house when a filament light bulb blows!!) so from this I assume the whole board is RCD protected.

Letting agents are invariably b*stards.

I would employ your own spark to do his own EICR and go from there.

Does it have a generator switch over or two sources of supply? One of the c2 comments seems a little bit odd.

Missing fuse carrier?

Is it a TT earth system with the 100a RCD before DB1?

Do people normally write reports like that - it sounds like the work of a mindless robot?! Items 14-17 are the only ones which appear (at least to me) to actually state explicitly what the alleged problem with the installation is - items 1 to 13 seem to just be statements (in some cases not very specific) about regulations/requirements, without any explicit indication of the manner in which the installation is alleged to have failed to satisfy the requirements. IN many cases, one can guess - but one surely shouldn't have to?!!

Quite apart from the questions about what is wrong with the installation and what, if anything, needs to be remedied, if I were the person paying for that report, I would be seriously unhappy with the way in which it had been written!

Kind Regards, John

Spark123 said:

Does it have a generator switch over or two sources of supply? One of the c2 comments seems a little bit odd.

Click to expand...

Not that I know of

GaryGarden said:

Is it a TT earth system with the 100a RCD before DB1?

Click to expand...

Huh?