Electrical insatallation

misterstingy

I've just had an 'electrical installation condition report' carried out on a property that I own. The report recommended 'replacing current mcbs with rcbos'.

What does that mean? What does it achieve? Is it a big job?

paulpud

It means replacing the trip switches you have at present with ones that will make the installation safer, improve compliance with latest regulations and also should prevent you from receiving a fatal electric shock.

It's shouldn't be a big job. Worst case would be to replace the consumer unit (fuseboard) you have at the moment with a more modern one capable of housing rcbos. If you already have a suitable consumer unit it would mean a simple task of replacing the individual mcb trips. The number of mcbs you have will influence the cost

Just remember it is just a recommendation, and it's not an obligation to have the work carried out.

dj1471

misterstingy wrote: »

What does that mean? What does it achieve? Is it a big job?

It means the electrician is looking for work.

It sounds like you already have a relatively modern consumer unit with RCD protection (refer to the EICR)? That being the case, there isn't a whole lot of benefit to changing to an RCBO setup - it won't improve safety or compliance with the regulations. Usually your consumer unit will have one or two RCDs to protect all the circuits, meaning that if the RCD trips you lose half or all of your circuits not just the one that caused the trip. With a full RCBO setup each circuit has its own RCD, so if something causes a trip on one circuit it won't affect the others.

If I was going to get a whole new consumer unit (which I am) I'd go for a full RCBO setup, but I don't think it's worth changing an existing installation.

If however you don't have RCD protection, then it is worth doing - speak to the electrician to understand how much work it'll be (depends on what you currently have) and shop around for the best price.

Ectophile

Just to translate some of the jargon here:

MCB = Miniature Circuit Breaker. An alternative to a fuse, which trips when a circuit is overloaded. It's mainly for fire safety.

RCD = Residual Current Device (used to be called a Current Operated Earth Leakage Circuit Breaker). A device that trips if it sees too much current leaking to earth. Mostly used to protect people from electrocution.

RCBO = Residual Current Breaker with Overload. An MCB and RCD combined into one unit, so it does both.

Modern wiring practice has all circuits protected by an RCD for safety. One way of doing this is to have two RCDs in a consumer unit, each protecting half the circuits. As RCBOs come down in price, an alternative is to give each circuit its own RCBO.

Older installations often have only one RCD protecting some circuits (particularly sockets and showers). Older installations still may not have an RCD at all.

Risteard

Ectophile wrote: »

Modern wiring practice has all circuits protected by an RCD for safety.

Assuming you are referring to RCDs with a rated residual operating current not exceeding 30mA used for additional protection, modern practice and Regulations do not require all circuits be so protected.

brightontraveller

misterstingy wrote: »

I've just had an 'electrical installation condition report' carried out on a property that I own. The report recommended 'replacing current mcbs with rcbos'.

What does that mean? What does it achieve? Is it a big job?

If you want informed answers you'd need too post more information installation, property type, use etc different situations require different solutions…?
Most have a report for a reason? Landlords because agents, local authorities insist? Sellers/ Buyers to increase decrease the price? Some because they have a prior problem, etc

thescouselander

I think there is a general misconception over how much protection RCD's provide. Yes, they'll save you in some circumstances but if you cause a short between live and neutral, for example by putting your finger in a light socket, you'll still get zapped.

Ectophile

Risteard wrote: »

Assuming you are referring to RCDs with a rated residual operating current not exceeding 30mA used for additional protection, modern practice and Regulations do not require all circuits be so protected.

That's strictly true, but most of the circuits in a house will need protecting for one reason or other. You have to go out of your way to design one that doesn't.

You need a 30mA RCD to protect:

• Anything that's supplying sockets,
• Any wiring that's buried in the plasterwork (think of the wiring drops to light switches, for instance), unless you use armoured cable,
• Anything that feeds a bathroom, or even just goes through the bathroom,
• Anything that feeds an appliance where the manufacturer says you need a 30mA RCD.

That's why most people just stick in a dual-RCD consumer unit and use that for everything.

Risteard

Ectophile wrote: »

Any wiring that's buried in the plasterwork (think of the wiring drops to light switches, for instance), unless you use armoured cable,

I prefer to use earthed galvanised conduit.

Ectophile

Risteard wrote: »

I prefer to use earthed galvanised conduit.

That'll work too!

misterstingy

Thanks for all the replies. It's looking like it might not be really necessary, but I'm still not clear on the pros & cons.

Here's some more details.

Flat is rented out to a tenant. Flat is in a purpose built block built about 2006. Modern fuse box with trip switches.

I got the report done because the letting agent suggested it. The only reason I would get the recommended change done is if it provides extra safety e.g. prevents a fire caused by an electrical fault or prevents a tenant being electrocuted.

If my reading of the replies is correct, the suggested change wouldn't give any benefits other than meaning that in the event of a switch being tripped, only one socket or group of sockets would go down instead of half the system.

Have I read that right?