Replace MCB with RCBO

[WilkoDontKnow]

Hi All,

I've recently bought a new house and all of the plug socket circuits are connected to 32a MCB's (5 in total) which are protected by a RCD . Obviously when something trips the RCD all of the sockets in the house are unusable so I'd like to replace the MCB's with RCBO's of the same rating and spec. The existing MCB's are Crabtree and I've found a BG compact RCBO which is the same physical size and uses the same DIN connector so should fit inside the CU.

I'd really appreciate it if anyone can help me with the questions below, I've had a look through various forums but find conflicting information:

1. Can I carry out this work rather than use an electrician

2. If I replaced each of the MCB's with RCBO, should I remove the RCD

Thanks in advance

 

[boltonsparky]

You're modifying the consumer unit beyond the manufacturer's design by using RCBOs from a different manufacturer and fitting RCBOs into a consumer unit that was designed as  split load RCD board which contravenes regulations. It wouldn't be wise to take it on yourself as I've had faulty RCBOs new out of the box so testing is a must (it is anyway).

Leaving the existing RCDs in you would have the same problem as whether the RCD or RCBO trips first is pot luck so you'd be no better off.

Rather than going half tilt you'd be better upgrading the whole board to an RCBO board with surge protection, the RCBOs should really be type A RCD now due to the ever increasing connected equipment that can blind type AC, the price difference is negligable. You'd need an electrician to do the work as it's notifiable and more importantly it would require testing before and afterwards which only somebody with calibrated equipment and the knowledge to use it would be able to do.

The bottom line is it isn't a DIY job.

 

[WilkoDontKnow]

You're modifying the consumer unit beyond the manufacturer's design by using RCBOs from a different manufacturer and fitting RCBOs into a consumer unit that was designed as  split load RCD board which contravenes regulations. It wouldn't be wise to take it on yourself as I've had faulty RCBOs new out of the box so testing is a must (it is anyway).

Leaving the existing RCDs in you would have the same problem as whether the RCD or RCBO trips first is pot luck so you'd be no better off.

Rather than going half tilt you'd be better upgrading the whole board to an RCBO board with surge protection, the RCBOs should really be type A RCD now due to the ever increasing connected equipment that can blind type AC, the price difference is negligable. You'd need an electrician to do the work as it's notifiable and more importantly it would require testing before and afterwards which only somebody with calibrated equipment and the knowledge to use it would be able to do.

The bottom line is it isn't a DIY job.

Thanks for the quick response! 

When doing multiple searches on this subject one of the areas that divides opinion is around using other manufacturers RCBO's. The argument being the one being replaced and the new one conform to BS EN 7671 then they should be OK, nothing mentioned contravening regulations though. Would mixing manufacturers be a regulatory issue?

I was solely looking to replace the MCB's with RCBO's on the sockets rather than all of the lights too hence why hoping to be able to carry out the work myself. When I looked at the Part P regs it looks like replacing the MCB with RCBO's is not notifiable as I would not be replacing the CU or installing a new circuit.

I'm sure most works involving electrics in the home would benefits from an electrician doing them so they can do testing etc, but I'd rather avoid the expense if I can do the work myself.

As a side note the current MCB's are type B so I would be looking to replace these with type B RCBO rather than type A.

 

[boltonsparky]

Thanks for the quick response! 

When doing multiple searches on this subject one of the areas that divides opinion is around using other manufacturers RCBO's. The argument being the one being replaced and the new one conform to BS EN 7671 then they should be OK, nothing mentioned contravening regulations though. Would mixing manufacturers be a regulatory issue?

I was solely looking to replace the MCB's with RCBO's on the sockets rather than all of the lights too hence why hoping to be able to carry out the work myself. When I looked at the Part P regs it looks like replacing the MCB with RCBO's is not notifiable as I would not be replacing the CU or installing a new circuit.

I'm sure most works involving electrics in the home would benefits from an electrician doing them so they can do testing etc, but I'd rather avoid the expense if I can do the work myself.

As a side note the current MCB's are type B so I would be looking to replace these with type B RCBO rather than type A.

BS7671 states that manufacturers instructions should be followed. Manufacturers type test their kit. If you contacted a manufacturer they would not approve you to fit other manufacturers kit in with theirs. You are essentially taking on and approving that design yourself which is where the problem lies with mixing protective devices from multiple manufacturers. It used to be far more common and isn't unusual to see a miss match of protective devices from various manufacturers in the same CU/DB.

An RCBO is two devices in one, an MCB and an RCD. The type A I mention refers to the type of RCD, the type B you mention refers to the type of MCB, two totally different things. 

You may save the expense but how are you going to test the RCBO, like I say I've had them faulty new out of the box. The expense is worth it to ensure you have a safe installation.

 

[WilkoDontKnow]

BS7671 states that manufacturers instructions should be followed. Manufacturers type test their kit. If you contacted a manufacturer they would not approve you to fit other manufacturers kit in with theirs. You are essentially taking on and approving that design yourself which is where the problem lies with mixing protective devices from multiple manufacturers. It used to be far more common and isn't unusual to see a miss match of protective devices from various manufacturers in the same CU/DB.

An RCBO is two devices in one, an MCB and an RCD. The type A I mention refers to the type of RCD, the type B you mention refers to the type of MCB, two totally different things. 

You may save the expense but how are you going to test the RCBO, like I say I've had them faulty new out of the box. The expense is worth it to ensure you have a safe installation.

Thanks again. The reason you gave re mixing of different manufactures make sense. An electrician recently added a supply to the garage and he used a Wylex MCB in the Crabtree CU I guess the difference here is he will have tested the MCB.

I was planning on testing the RCBO with a Kewtech Loopcheck 107 which I believe has a 30mA RCD check but as it doesn't test how long it takes to trip I'm not sure if you would consider that an effective test.

So in summary, it sounds like although I am allowed to swap out the MCB for RCBO myself (if I use the same manufacturer), it's probably not advisable due to not being able to carry out effectiveness testing.

 

[Murdoch]

When doing multiple searches on this subject one of the areas that divides opinion is around using other manufacturers RCBO's. The argument being the one being replaced and the new one conform to BS EN 7671 then they should be OK, nothing mentioned contravening regulations though. Would mixing manufacturers be a regulatory issue?

I was solely looking to replace the MCB's with RCBO's on the sockets rather than all of the lights too hence why hoping to be able to carry out the work myself. When I looked at the Part P regs it looks like replacing the MCB with RCBO's is not notifiable as I would not be replacing the CU or installing a new circuit.

I'm sure most works involving electrics in the home would benefits from an electrician doing them so they can do testing etc, but I'd rather avoid the expense if I can do the work myself.

As a side note the current MCB's are type B so I would be looking to replace these with type B RCBO rather than type A.

There is no divide of opinion with qualified competent sparks - max and matching is no longer allowed.

The problem with DIYers changing electrics isn't just about testing - its about the correct earthing, bonding, design and installation ....... 

 

[Murdoch]

Thanks again. The reason you gave re mixing of different manufactures make sense. An electrician recently added a supply to the garage and he used a Wylex MCB in the Crabtree CU I guess the difference here is he will have tested the MCB.

Did he give you a certificate?

and its not possible to "test" a MCB

 

[boltonsparky]

Thanks again. The reason you gave re mixing of different manufactures make sense. An electrician recently added a supply to the garage and he used a Wylex MCB in the Crabtree CU I guess the difference here is he will have tested the MCB.

I was planning on testing the RCBO with a Kewtech Loopcheck 107 which I believe has a 30mA RCD check but as it doesn't test how long it takes to trip I'm not sure if you would consider that an effective test.

So in summary, it sounds like although I am allowed to swap out the MCB for RCBO myself (if I use the same manufacturer), it's probably not advisable due to not being able to carry out effectiveness testing.

I believe crabtree and wylex are of the same parent group, Electrium, so they may be approved for use together, I'm not sure, it's not something I've looked into. I know wylex are a nightmare just within their own brand for fitting to their own different types of busbars. 

 

[WilkoDontKnow]

Did he give you a certificate?

and its not possible to "test" a MCB

Yes he did he also did a full inspection of the CU and checked all the various circuits, wiring etc since the CU was installed in 2008 and there is a mix of old a new wiring standards throughout the house. This was only in October so I'm concerned if he installed a different brand of MCU when it's no longer allowed.

 

[Murdoch]

Yes he did he also did a full inspection of the CU and checked all the various circuits, wiring etc since the CU was installed in 2008 and there is a mix of old a new wiring standards throughout the house. This was only in October so I'm concerned if he installed a different brand of MCU when it's no longer allowed.

Yes, he should know that mix and matching circuit breakers is no longer allowed ......

Recommend you email him and ask him the question and see what he says.

 

[SPECIAL LOCATION]

Industry guidance states:-

Devices such as circuit-breakers and RCBOs from different manufacturers must not be mixed unless documentation is obtained from the consumer unit manufacturer which confirms that the specific mixed arrangement is suitable for use. Further guidance on this can be found on the BEAMA website www.beama.org.uk

see also:-

https://www.beama.org.uk/static/uploaded/ecbea4e2-4db6-453d-89ab17f790a71ea9.pdf 

and Reg 510.3

All circuits should be designed to fail-safe..  (not just work)

Any idiot can join a few wires to make something work..

Ensuring it is tested correctly to verify compliance with BS7671 requires a bit more expertise..

Alteration work should still have an electrical certificate issued irrespective of if it is Part-P notifiable or not..

The tester plug described does not have the capacity to give the readings needed to complete an electrical certificate.

(Or to put it another way..  if a £40 tester was sufficient for BS7671 compliance, then most electricians would not be spending around £500+ on test meters. )

Also BS7671 requires you to verify earthing and bonding before doing any alterations temp or permanent,  (see 132.16)

Your plug cannot verify external loop impedance or prospective fault current that should be checked if changing the characteristics of a CU.

Avoiding expense can be very expensive if you get it wrong..   As electricity will kill a healthy adult in less than a second..   

There is a court case ongoing at the moment with regard to a youngster who was fatally electrocuted..

If you can obtain a written declaration from both Crabtree & BG stating that the devices you propose will operate to the correct standards..

Then go ahead..

If not.. then I wouldn't want to be the one remembering the few pounds saved in the event of the device failing at a critical moment..

:coffee

 

[boltonsparky]

As electricity will kill a healthy adult in less than a second..   

I always find people's attitudes to electricity interesting. In most cases they wouldn't cut their own hair as they don't have the skill and the worst that can happen there is that you walk down the street looking like a numpty or have to put on a hat, yet something that can kill you, seriously injure you, burn your house down or financially ruin you when your insurance refuses to pay out they're quite happy to crack on with and have a bash at it. 

 

[phil d]

I always find people's attitudes to electricity interesting. In most cases they wouldn't cut their own hair as they don't have the skill and the worst that can happen there is that you walk down the street looking like a numpty or have to put on a hat, yet something that can kill you, seriously injure you, burn your house down or financially ruin you when your insurance refuses to pay out they're quite happy to crack on with and have a bash at it. 

Oh come on, it's only a few wires!

We do all our learning and spend all our money on test gear because we don't want to go out and blow it on beer and women. lol

 

[Murdoch]

Gas you can smell

Water you can see and feel

Electricity you can't see but when you feel it may kill you

I always find it odd that people will have a go at electrics but few gas or water

 

[Sidewinder]

Yes he did he also did a full inspection of the CU and checked all the various circuits, wiring etc since the CU was installed in 2008 and there is a mix of old a new wiring standards throughout the house. This was only in October so I'm concerned if he installed a different brand of MCU when it's no longer allowed.

It has not been legal probably since the late 1970’s.

When you mix and match in a consumer unit, you create a new product which has legal requirements for safety which cannot be met in situ once installed.

The electrcial installer that did the work in your garage has worked outside the scope of his membership scheme if he has one, outside the scope of BS7671, outside the scope of the product standards for consumer units, outside the requirements of the Electricity at Work Regulations (law)  and outside the scope of the Electrical Equipment Safety Regulations (law again).

He is also likely to be uninsured for the work, as he has legally manufactured a product and placed the product on the market, thus he needs product liability insurance, not many electrical installers would have that as it is not generally part if the scope of work they consciously undertake.

If you change the brand of the devices fitted then you are also going to be doing something outside the scope of the law and you will personally become the manufacturer of the assembly.

You will also likely invalidate your home insurance, if that has not already been done by the installer who worked on your garage.

In the event of a fire and a forensic investigation by your home insurer it is likely that your claim would be refused and you would have to claim from the installer, who unless correctly insured, is unlikely to be able to pay for the repairs themselves and you are then going to end up having to persue a case against the installer yourself, if the installer can pay.

 

[WilkoDontKnow]

It has not been legal probably since the late 1970’s.

When you mix and match in a consumer unit, you create a new product which has legal requirements for safety which cannot be met in situ once installed.

The electrcial installer that did the work in your garage has worked outside the scope of his membership scheme if he has one, outside the scope of BS7671, outside the scope of the product standards for consumer units, outside the requirements of the Electricity at Work Regulations (law)  and outside the scope of the Electrical Equipment Safety Regulations (law again).

He is also likely to be uninsured for the work, as he has legally manufactured a product and placed the product on the market, thus he needs product liability insurance, not many electrical installers would have that as it is not generally part if the scope of work they consciously undertake.

If you change the brand of the devices fitted then you are also going to be doing something outside the scope of the law and you will personally become the manufacturer of the assembly.

You will also likely invalidate your home insurance, if that has not already been done by the installer who worked on your garage.

In the event of a fire and a forensic investigation by your home insurer it is likely that your claim would be refused and you would have to claim from the installer, who unless correctly insured, is unlikely to be able to pay for the repairs themselves and you are then going to end up having to persue a case against the installer yourself, if the installer can pay.

Thanks for the input (and to everyone else who has contributed so far). From a consumer perspective it seems crazy that an electrician can fit something in a consumer unit that in most cases the consumer would never check, or have the knowledge to check for and that could leave them in a situation where the home insurance is invalid. In the document SPECIAL LOCATION linked earlier it states you shouldn't even put new equipment in an old consumer unit assembly so potentially unless the electrician can get the exact same MCB or RCBO as what was originally installed then you would need an new consumer unit installed. Wouldn't it make more sense for every manufacturer to work to a given standard then if you use a MCB of that was manufactured to that standard then there is no issue.

I'm well on truly off the idea of doing the work myself which I'm sure you are all glad to hear but I can't get my head around the anti-consumer product standards. Is a BG 32A type B MCB really going fundamentally change the working of the consumer unit than a Crabtree 32A type B MCB? Is there any research/evidence as to the number of fires etc. this practice has caused or is it more market protection by the manufacturers? I'm genuinely interested since I'll be a paying an electrician anyway and probably will do every few years when they can't get hold of an identical part

 

[SPECIAL LOCATION]

Thanks for the input (and to everyone else who has contributed so far). From a consumer perspective it seems crazy that an electrician can fit something in a consumer unit that in most cases the consumer would never check, or have the knowledge to check for and that could leave them in a situation where the home insurance is invalid. In the document SPECIAL LOCATION linked earlier it states you shouldn't even put new equipment in an old consumer unit assembly so potentially unless the electrician can get the exact same MCB or RCBO as what was originally installed then you would need an new consumer unit installed. Wouldn't it make more sense for every manufacturer to work to a given standard then if you use a MCB of that was manufactured to that standard then there is no issue.

I'm well on truly off the idea of doing the work myself which I'm sure you are all glad to hear but I can't get my head around the anti-consumer product standards. Is a BG 32A type B MCB really going fundamentally change the working of the consumer unit than a Crabtree 32A type B MCB? Is there any research/evidence as to the number of fires etc. this practice has caused or is it more market protection by the manufacturers? I'm genuinely interested since I'll be a paying an electrician anyway and probably will do every few years when they can't get hold of an identical part

Is all to do the manufactures covering their backsides!    

Or as we used to call it technical tag..  whoever touched it last gets the blame unless they can pass the buck!!

You are correct it would be far easier if every manufacture had to produce to a fully compatible standard that was interchangeable...

It would make our jobs much easier... 

But as they don't have to, providing they can prove their own equipment does what it says on the box they are happy..

Why would they waste time & money verifying if every other manufactures products are fully compliant and compatible with their equipment? 

Similar to loads of hardware & software compatibility issues between, computers, tablets, smart phones etc.. from different makes..

But your IT equipment generally wont kill you, just maybe lose some data!

You will also find your car insurance is invalid if you have done some non-manufacture spec alterations..   even though the car may technically pass an MOT. 

Some of the problem with MCB's/RCD's/RCBO's is any adverse effects or influences by or from any devices in the adjoining slots on the CU..

due to heat or magnetism generated when electricity flows though a circuit..  

e.g. during a short circuit an MCB has to disconnect a high current very quickly, whilst also preventing the MCB from overheating itself..

Or the MCB next to it!

In many cases they could well work perfectly ok..?

BUT without spending the time & money to fully test and verify that they do..

no one in their right mind would actually state in writing that it is acceptable..

Who are you going to get to pay for it?

When its cheaper to just say.. 

"Our devices must be used in our enclosures"

They just leave it for the poor old electricians & customers to battle it out between each other in a blaze of confusion!

:C

 

[Sidewinder]

Thanks for the input (and to everyone else who has contributed so far). From a consumer perspective it seems crazy that an electrician can fit something in a consumer unit that in most cases the consumer would never check, or have the knowledge to check for and that could leave them in a situation where the home insurance is invalid. In the document SPECIAL LOCATION linked earlier it states you shouldn't even put new equipment in an old consumer unit assembly so potentially unless the electrician can get the exact same MCB or RCBO as what was originally installed then you would need an new consumer unit installed. Wouldn't it make more sense for every manufacturer to work to a given standard then if you use a MCB of that was manufactured to that standard then there is no issue.

I'm well on truly off the idea of doing the work myself which I'm sure you are all glad to hear but I can't get my head around the anti-consumer product standards. Is a BG 32A type B MCB really going fundamentally change the working of the consumer unit than a Crabtree 32A type B MCB? Is there any research/evidence as to the number of fires etc. this practice has caused or is it more market protection by the manufacturers? I'm genuinely interested since I'll be a paying an electrician anyway and probably will do every few years when they can't get hold of an identical part

The manufacturers do work to international standards, which requires testing of the product in all configurations, which they have to do, for their product.

If you want to pay probably over £100k for a consumer unit then you might be able to get one that you could fit different manufacturers breakers in, but not every companies and it mighbe a snapshot in time.

Additionally the company doing the certification would not have control over the product that they don’t make, so they would likely be reluctant to take legal responsibility for it.

 

[Sidney]

I can't get my head around the anti-consumer product standards. Is a BG 32A type B MCB really going fundamentally change the working of the consumer unit than a Crabtree 32A type B MCB?

Although the DIN rail, the bit the MCB/RCBO mounts onto, is a standard design the internal layout of the DB does vary between manufacturers. The poistion of the clamps that secure onto the busbar can vaary by a couple of mm which means the device will not be securely terminated with a potential for overheating and fire.

The bit that sticks out of the cover with the toggle on it isn't a generic size meaning gaps can be left affecting the IP rating of the board and sometimes stops covers from being fitted or closed properly.

All boards and devicesa are types tested and have a rating at whch they can safely handle any large fault currents without becoming unsafe, potentially they can 'blow up' causing damage to persons and property.

Occasionally you may see mixed manufacturers makes of device in a board which ar eperfectly safe, for example Merlin Gerin rebranded to Schneider a few years ago with a change of logo and colour scheme etc but their devices remained the same and were fully compatible.

Even manufacturers have varying ranges which may not be compatible with other products within their ranges. For example a Crabtree Loadstar will not correctly fit in a Crabtree Starbreaker board. A Schneider C60H MCB is compatible with a Merlin Gerin board but a Schneider iC60H isn't.

The whole subject is a minefield and many electrical forums have numerous posts asking if anyone knows what devices will fit which boards.

In Chapter 13 of BS7671 there's a part that covers this subject, basically says follow manufacturers instructions, if you don't you're fully responsible for any problems that arise from it.

There's a very large percentage competant electricians out there that take pride in their work, sadly there's a very small number that shoud be allowed to carry out electrical work due to their blarze attitude towards safety and their insability to even tie their own laces...

 

[binky]

as far as being notifiable works, I'm fairly sure the regs say something about 'altering the electrical charactersistics of a cct', I would argue swopping an MCB for an RCBO would fall within this definition?

Locked to prevent hi-jacking (again)