Metal CU. Why?

[LastManOnline]

Metal CU.

Am curious to know why the UK regs demanded a metal CU. Would it not have been helpful to first investigate what was causing overheating the CU?

 

[ferg]

I think the idea is for the enclosure to not add fuel to any consumer unit fire.

It's all very well pointing the finger at poor workmanship and materials but reality tells us they exist and the metal CU is to mitigate this.

 

[Dartlec]

Metal CU.

Am curious to know why the UK regs demanded a metal CU. Would it not have been helpful to first investigate what was causing overheating the CU?

I think anyone who had ever worked with them knew that it was loose connections in almost all cases.

It seems like it was more the case of - what's a simple solution that we can implement to show we're doing something - possibly with the input of the manufacturers who didn't want to have to do anything costly.

Though in theory the Regs only demand a CU is made of an 'incombustible' material and suggest metal as one option. I assume that steel is just the cheapest way of achieving that.

 

[telectrix]

It seems like it was more the case of - what's a simple solution that we can implement to show we're doing something - possibly with the input of the manufacturers who didn't want to have to do anything costly.

WINNER.

 

[James]

Asbestos is non combustible, I think it might come back in to fashion.

 

[LastManOnline]

Metal CU.

Am curious to know why the UK regs demanded a metal CU. Would it not have been helpful to first investigate what was causing overheating the CU?

But back to my original question. WHY the change?. WHAT exactly was the reasoning behind the necessity to change from pvc to metal?

 

[telectrix]

because the London Fire Brigade attributed several fires as originating from inside Consumer Units. rather than address the cause of poor installation practice and possibly cheap shoddy components, it was decided by the suits that it was a good idea to allow the CU fires to continue but encase them in a metal box to stop the fire spreading to granny's inflammable underwear on a clothes horse under the stairs in front of the CU.

 

[Dartlec]

But back to my original question. WHY the change?. WHAT exactly was the reasoning behind the necessity to change from pvc to metal?

I believe it was input from the fire brigade on the number of fires being caused, but I'm not sure what evidence they had that plastic was the main problem...

 

[LastManOnline]

But back to my original question. WHY the change?. WHAT exactly was the reasoning behind the necessity to change from pvc to metal?

Should have said that they were considering making the same change here (ROI) where we often "copy and paste" UK regs. Curiously they passed on this one. I agree as I have never experienced a fire at a CU (DB.) I have the same uneasy feelings about this one as, I have about AFDD, s.

 

[Lucien Nunes]

I recall that some CUs were tested and the plastic casing was found to be made from material that was not correctly self-extinguishing. Whilst one would hope that no part of a CU would ever ignite, nonetheless there are components inside that could be expected to arc violently in the event of a catastrophic fault. So there is a certain login in not wanting those components to be housed in a flammable box, which is what some cheap plastic CUs turned out to be. 100 years ago, it was accepted that while an asbestos-lined wooden box was attractive, cast-iron switchgear with porcelain insulators, i.e. completely non-combustible materials throughout, was less of a fire risk.

 

[Dartlec]

I recall that some CUs were tested and the plastic casing was found to be made from material that was not correctly self-extinguishing. Whilst one would hope that no part of a CU would ever ignite, nonetheless there are components inside that could be expected to arc violently in the event of a catastrophic fault. So there is a certain login in not wanting those components to be housed in a flammable box, which is what some cheap plastic CUs turned out to be.

Sounds like they might have been better specifying a proper standard for self-extinguishing plastic then?

It would be interesting to know if they properly assessed the risk of metal enclosures (in TT installations particularly) being properly earthed, vs the advantages of metal.

 

[LastManOnline]

I recall that some CUs were tested and the plastic casing was found to be made from material that was not correctly self-extinguishing. Whilst one would hope that no part of a CU would ever ignite, nonetheless there are components inside that could be expected to arc violently in the event of a catastrophic fault. So there is a certain login in not wanting those components to be housed in a flammable box, which is what some cheap plastic CUs turned out to be.

I ca

I recall that some CUs were tested and the plastic casing was found to be made from material that was not correctly self-extinguishing. Whilst one would hope that no part of a CU would ever ignite, nonetheless there are components inside that could be expected to arc violently in the event of a catastrophic fault. So there is a certain login in not wanting those components to be housed in a flammable box, which is what some cheap plastic CUs turned out to be. 100 years ago, it was accepted that while an asbestos-lined wooden box was attractive, cast-iron switchgear with porcelain insulators, i.e. completely non-combustible materials throughout, was less of a fire risk.

Appreciate that but I personally have NEVER experienced a fire at a DB (CU). What is, occurring in the UK that makes, it implement these, measures? What makes the UK situation more vulnerable to fires?

 

[Dartlec]

Appreciate that but I personally have NEVER experienced a fire at a DB (CU). What is, occurring in the UK that makes, it implement these, measures? What makes the UK situation more vulnerable to fires?

At a guess, screwfix £50 boards being thrown onto the wall by people who don't know what torque is?

Not sure if that's an issue in the same way over there?

 

[LastManOnline]

At a guess, screwfix £50 boards being thrown onto the wall by people who don't know what torque is?

Not sure if that's an issue in the same way over there?

It's not just against regulations but it's actually against the law over here for a layperson to install a CU. In fact it is now against the law for a qualified electrician to take the cover off a CU in a domestic installation unless he is a registered contractor as well as been a conventionally trained electrician. A little OTT I know but that's where we are at the Mo.

 

[Dartlec]

It's not just against regulations but it's actually against the law over here for a layperson to install a CU. In fact it is now against the law for a qualified electrician to take the cover off a CU in a domestic installation unless he is a registered contractor as well as been a conventionally trained electrician. A little OTT I know but that's where we are at the Mo.

Interesting - not sure that would go down well here Though I guess it would be consistent with Gas Regs. But pointless if it's not enforced anyway...

 

[westward10]

It's not just against regulations but it's actually against the law over here for a layperson to install a CU. In fact it is now against the law for a qualified electrician to take the cover off a CU in a domestic installation unless he is a registered contractor as well as been a conventionally trained electrician. A little OTT I know but that's where we are at the Mo.

Are you an REC.

 

[LastManOnline]

Interesting - not sure that would go down well here Though I guess it would be consistent with Gas Regs. But pointless if it's not enforced anyway...

it is been strictly enforced here.My inspector (we currently get 1 inspection a year) has made a point in recent years of highlighting the number of people fined or jailed for contravening the law (previously known as "the regs").
Anyway here's a thought regarding my original question. There are many foreigners in my area with homes, some resident, some holiday. I notice that those most likely to carry out their own electricial work are from UK. I wondered could this be a factor in your issues with CU fires?.
[automerge]1601326578[/automerge]

Are you an REC.

Yes

 

[pc1966]

I notice that those most likely to carry out their own electricial work are from UK. I wondered could this be a factor in your issues with CU fires?.

I'm not sure there has been a massive increase in DIY activity for CUs to explain fire matters in recent years.

While you see a few pop up here asking for advice, I suspect the main issue for CU fires has been "professionals" who are useless at electrics. Not just the builders & plumbers who have a go and get berated here, but also a general de-skiling of the trade due to the loss of apprenticeships and the pressure to get qualifications in a few week's worth of a course.

While I am in favour of torque screwdrivers (on the same principle that I would always use a torque wrench for doing a cylinder head, etc) the recent increase in that aspect is probably also down to poorer skills/experience, and maybe poorer products with less tolerance to tightening effort, all down to the same issue.

 

[LastManOnline]

I'm not sure there has been a massive increase in DIY activity for CUs to explain fire matters in recent years.

While you see a few pop up here asking for advice, I suspect the main issue for CU fires has been "professionals" who are useless at electrics. Not just the builders & plumbers who have a go and get berated here, but also a general de-skiling of the trade due to the loss of apprenticeships and the pressure to get qualifications in a few week's worth of a course.

While I am in favour of torque screwdrivers (on the same principle that I would always use a torque wrench for doing a cylinder head, etc) the recent increase in that aspect is probably also down to poorer skills/experience, and maybe poorer products with less tolerance to tightening effort, all down to the same issue.

That is certainly an interesting point about the de-skilling taking place in the trade. I was, nt aware of that. What was the general reaction to the introduction of the metal CU like among sparks in general.? After all, working with metal is usually more labour intensive than plastic

 

[telectrix]

it's aknown fact that if Fire Brigade can't determine the cause of a fire, it's always put down as an electrical fault.

 

[pc1966]

I think it is true that there are a lot of fires that are electrically started, but I also suspect the majority are not due to fixed building wiring but are defective appliances.

For example, it was a fridge-freezer that started the Genfell fire, the worst in UK recent history. But the main reasons that led to such a great loss of life was lax building standards and, to a some degree, various issues relating to fire-fighting. But usually it is things like tumble dryers that are more common fire hazards it seems.

I can't speak for others but I am in favor of metal CU, it just seems sensible to have something that is reasonably tough and fire-resistant even if the risk from a well-fitted CU is negligible. But as mentioned, a decent grade of plastic that meets fire containment and LSOF behavior would be fine as well.

Perhaps they don't trust industry and/or cheap imports to keep meeting a specific grade of plastic, but "is it metal?" is harder to dodge. Who knows?

 

[StephenRowley]

Is it really that more taxing to install a metal CU than plastic enough to actually worry too mcuh about the requirements for the CU to metal?

 

[LastManOnline]

I think it is true that there are a lot of fires that are electrically started, but I also suspect the majority are not due to fixed building wiring but are defective appliances.

For example, it was a fridge-freezer that started the Genfell fire, the worst in UK recent history. But the main reasons that led to such a great loss of life was lax building standards and, to a some degree, various issues relating to fire-fighting. But usually it is things like tumble dryers that are more common fire hazards it seems.

I can't speak for others but I am in favor of metal CU, it just seems sensible to have something that is reasonably tough and fire-resistant even if the risk from a well-fitted CU is negligible. But as mentioned, a decent grade of plastic that meets fire containment and LSOF behavior would be fine as well.

Perhaps they don't trust industry and/or cheap imports to keep meeting a specific grade of plastic, but "is it metal?" is harder to dodge. Who knows?

I think it is true that there are a lot of fires that are electrically started, but I also suspect the majority are not due to fixed building wiring but are defective appliances.

Agree 100% on this point about the fixed wiring not been the origin of electrical fires. Statistics on this one not easy to come by. Secondly I would have no objection to installing metal CU, s in domestic installs providing there are sound and justifiable reasons for doing so. I struggle a little with the concept of having to adjust the materials because of poor installation skills on the part of untrained/semi trained personnel. I would prefer if the issue was approached from the direction of upskilling the personell

 

[StephenRowley]

I don't think it's necessary because of them expecting poor workmanship. It's just an additional safety precaution in case someone does make a slip up nobody's prefect, although it may have been overly cautious.

What's that old saying "if you haven't done anything wrong you haven't done anything"

 

[Dustydazzler]

it's aknown fact that if Fire Brigade can't determine the cause of a fire, it's always put down as an electrical fault.

I suppose years ago it could have been attributed to old Doris falling asleep with a lit cigarette in her mouth , but hardly anyone smokes these days so Cigarette fires must be on the fall...

 

[James]

Wouldn’t it be nice if you could get consumer units made of glass or other transparent non flammable material?

Might force a bit more pride in some people’s work.

There have been a few installations posted on here that look so good it is almost a crime to cover them up!

 

[Pete999]

Metal CU.

Am curious to know why the UK regs demanded a metal CU. Would it not have been helpful to first investigate what was causing overheating the CU?

Question What are Junior and Senior Trades qualifications issued in IRELAND? out of interest
[automerge]1601391413[/automerge]

Wouldn’t it be nice if you could get consumer units made of glass or other transparent non flammable material?

Might force a bit more pride in some people’s work.

There have been a few installations posted on here that look so good it is almost a crime to cover them up!

Seen a few that need covering up though

 

[LastManOnline]

Question What are Junior and Senior Trades qualifications issued in IRELAND? out of interest
[automerge]1601391413[/automerge]

Seen a few that need covering up though

I assume you meant When they are issued? If nothing has changed since I came out of my time, than junior trades after 2 years and senior trades on year 4.Some sparks would then simultaneously do the C&G equivalent

 

[Pete999]

I assume you meant When they are issued? If nothing has changed since I came out of my time, than junior trades after 2 years and senior trades on year 4.Some sparks would then simultaneously do the C&G equivalent

Thanks Ed, but what exactly are the two Quals, Junior and senior what do they equate to? City and Guilds wise
[automerge]1601392593[/automerge]

I assume you meant When they are issued? If nothing has changed since I came out of my time, than junior trades after 2 years and senior trades on year 4.Some sparks would then simultaneously do the C&G equivalent

OK but what are the CnG equivalent? not an unreasonable question I think.

 

[LastManOnline]

Thanks Ed, but what exactly are the two Quals, Junior and senior what do they equate to? City and Guilds wise
[automerge]1601392593[/automerge]

OK but what are the CnG equivalent?

Apologies. I don't believe the Junior trades has an equivalent in The UK. The Senior trades used to be equivalent to the C&G course B. That's how it was in my time. (For "my time" read "old fogies")

 

[Pete999]

Apologies. I don't believe the Junior trades has an equivalent in The UK. The Senior trades used to be equivalent to the C&G course B. That's how it was in my time. (For "my time" read "old fogies")

Thanks so, Junior trades = Electrician, Senior Trades = Approved Electricians, old fogeys need not apply

 

[LastManOnline]

Thanks so, Junior trades = Electrician, Senior Trades = Approved Electricians, old fogeys need not apply

Junior trades is an examine carried out after the first 2 years of your apprenticeship is completed. Success in that allows you proceed to the Senior. Trades. Pass this and you are now an approved electrician.
Traditionally, if you did, nt pass this exam you would still work as an electrician, but your routes to further opportunities would be restricted. Nowadays however, not passing all your exams would definately be an issue

 

[Pete999]

Junior trades is an examine carried out after the first 2 years of your apprenticeship is completed. Success in that allows you proceed to the Senior. Trades. Pass this and you are now an approved electrician.
Traditionally, if you did, nt pass this exam you would still work as an electrician, but your routes to further opportunities would be restricted. Nowadays however, not passing all your exams would definately be an issue

Agree Mate 5 or 6 weeks at a training centre, a few hundred quid, job done, simples, innit?





'

 

[Midwest]

Here’s a couple of links from Electrical Safety First, a charity organisation in UK, and the IET, with their views on the subject, FYI @Edmond Noonan. There’s various others that give the reasoning, or context if you will.

https://www.electricalsafetyfirst.org.uk/media/1258/consumer-unit-connections.pdf

Consumer Unit Mythbuster | Electrical Safety First

Consumer Unit Mythbuster From 1st January, consumer units and similar switchgear assemblies installed in domestic premises must either have their enclosure cons

www.electricalsafetyfirst.org.uk

https://electrical.------.org/wirin...tection-against-fire-the-fire-officer-s-view/

 

[stewartrossinv]

Having recently retired from Scottish Fire and Rescue, could I correct some misimpressions? Firstly, all fire services in England, Scotland and Wales use a central system for recording incidents. The majority of fires start in the kitchen from human factors. Electrical fires are a much smaller subset of the total - of which fires in domestic appliances such as tumble driers or fridge-freezers are of greater numbers than those listed as supply-related (which would include overheating in the consumer unit).

Fire investigation teams are called to major fires or those where there has been loss of life. Fire investigators look for evidence to support their conclusions, so electrical causes are not assumed as a default unless there is evidence to support such a conclusion.

London Fire Brigade has done a great job of drawing attention to lethal Whirlpool drier faults and Lec fridge freezers, whose spark suppression capacitors were found to go short-circuit and then go on fire. Consumer units fires are much more rare - unless you look at criminal behaviour such as interfering with the meter to feed a cannabis farm for instance!

 

[ipf]

I'm not sure there has been a massive increase in DIY activity for CUs to explain fire matters in recent years.

While you see a few pop up here asking for advice, I suspect the main issue for CU fires has been "professionals" who are useless at electrics. Not just the builders & plumbers who have a go and get berated here, but also a general de-skiling of the trade due to the loss of apprenticeships and the pressure to get qualifications in a few week's worth of a course.

While I am in favour of torque screwdrivers (on the same principle that I would always use a torque wrench for doing a cylinder head, etc) the recent increase in that aspect is probably also down to poorer skills/experience, and maybe poorer products with less tolerance to tightening effort, all down to the same issue.

That's right. The 'domestic installer' system has a lot to do with it, for me. As you say, the general de-skilling. It's a case of dumbing down to suit trade standards.
You could have a domestic installer with very little experience and a qualified spark with 30 years.....if the sparks not registered, scam wise, who would you sooner have testing and signing off a completion certificate?
The old cash cow, basically.

 

[LastManOnline]

Having recently retired from Scottish Fire and Rescue, could I correct some misimpressions? Firstly, all fire services in England, Scotland and Wales use a central system for recording incidents. The majority of fires start in the kitchen from human factors. Electrical fires are a much smaller subset of the total - of which fires in domestic appliances such as tumble driers or fridge-freezers are of greater numbers than those listed as supply-related (which would include overheating in the consumer unit).

Fire investigation teams are called to major fires or those where there has been loss of life. Fire investigators look for evidence to support their conclusions, so electrical causes are not assumed as a default unless there is evidence to support such a conclusion.

London Fire Brigade has done a great job of drawing attention to lethal Whirlpool drier faults and Lec fridge freezers, whose spark suppression capacitors were found to go short-circuit and then go on fire. Consumer units fires are much more rare - unless you look at criminal behaviour such as interfering with the meter to feed a cannabis farm for instance!

A very helpful post. And it bears out, in my view what the average spark experiences as alluded to already by pc1966. Fixed wiring would appear to be the least problematic area in electrical fires and appliances the major contributor.
[automerge]1601407707[/automerge]

Here’s a couple of links from Electrical Safety First, a charity organisation in UK, and the IET, with their views on the subject, FYI @Edmond Noonan. There’s various others that give the reasoning, or context if you will.

https://www.electricalsafetyfirst.org.uk/media/1258/consumer-unit-connections.pdf

Consumer Unit Mythbuster | Electrical Safety First

Consumer Unit Mythbuster From 1st January, consumer units and similar switchgear assemblies installed in domestic premises must either have their enclosure cons

www.electricalsafetyfirst.org.uk

https://electrical.------.org/wirin...tection-against-fire-the-fire-officer-s-view/

Good read. Thanks for posting those links. I am a big fan of Electrical Safety First. They have always been prepared to stick their heads above the parapet and go against the flow. Respect. They have (like pc1966) really highlighted the degree to which poor workmanship has contributed to problems. That comes as a surprise to me. It's so far not an issue overhere but of course things can change. Unfortunately that final link did, nt work. Looks interesting. As, firemen are obviously on the front line and have firsthand experience of the real issues

 

[Midwest]

That's right. The 'domestic installer' system has a lot to do with it, for me. As you say, the general de-skilling. It's a case of dumbing down to suit trade standards.
You could have a domestic installer with very little experience and a qualified spark with 30 years.....if the sparks not registered, scam wise, who would you sooner have testing and signing off a completion certificate?
The old cash cow, basically.

I dunno. There’s some short course sparks on here, and although I’ve not seen their work, because of their knowledge and the way they talk of things, I would be happy to recommend them.

On the flip side of that, I’ve worked with many sparks who’ve served the traditional apprenticeship. Most were good, very professional, but some I wouldn’t trust as far as I could throw em.

 

[Strima]

The spike in fiers also coincides with the start of the installation of smart meters, not that I'm suspicious or anything like that or saying smart meter fitters couldn't even tie their own shoelaces...

 

[Midwest]

The spike in fiers also coincides with the start of the installation of smart meters, not that I'm suspicious or anything like that or saying smart meter fitters couldn't even tie their own shoelaces...

Bear in mind, all new builds get a new meter fitted, have done for years. Do they have specific smart meter replacement operatives?

 

[pc1966]

Unfortunately that final link did'nt work. Looks interesting. As, firemen are obviously on the front line and have firsthand experience of the real issues

This forum borks links to the IET site for reasons that are not obvious. However, the important bits from the article (to me at least) are quoted below:

Fires in plastic consumer units - a pattern of fires emerges

Back in 2011, the Fire Investigation Team identified an increase in the number and severity of fires involving consumer units. The team started looking carefully at the cause of those fires and established that there were issues with high resistance connections, where cables were not secured properly. This had the potential to lead to localised heating, arcing and, in some cases, to fires. There was also an emerging problem due to a large batch (over 1 million units) of non-compliant miniature circuit breakers (MCBs), which were subject to a product recall and which could also fail catastrophically.

Severe fires

The team were also seeing more fires that were spreading beyond the consumer unit and putting people’s lives at risk. Through a careful process of laboratory examinations and tests at Brigade consultant scientists Bureau Veritas, concern was raised about the flammability of the plastic enclosures of consumer units. Working closely with Electrical Safety First, more extensive tests of five plastic consumer units from different manufactures were carried out in 2012. These tests gave significant cause for concern due to the intensity of the fire and the levels of toxic smoke produced.

Location, location, location

A significant cause for concern when a consumer unit becomes involved in a fire is that it is commonly located on an escape route, for example, under the stairs or behind the front door. When this is combined with the fairly usual situation of coats, outdoor wear and other household items being stored nearby, once the fire starts, it often develops very quickly. London Fire Brigade was becoming extremely alarmed at the number of injuries occurring at such fires and the need for people to be rescued as they became trapped when the escape route was involved in fire.

A way forward

Working with Electrical Safety First, industry body BEAMA and other stakeholders, the process of presenting evidence for change began. A JPEL/64 project group was set up and ‘robust’ discussions about possible changes to BS 7671 (the Wiring Regulations) continued over several months.

Representatives from the Department of Communities and Local Government (DCLG) attended and raised concerns about possible changes. As a result of these concerns, DCLG commissioned independent tests at the Building Research Establishment (BRE). BRE tested two plastic and two metal consumer units and the subsequent report appeared to strongly support the need for change, stating:

“Both plastic consumer units caught fire and their casings became involved in the fire”… … “Both metal consumer units contained the fire within the unit” (Source: BRE report BD2890)

Also, some manufacturers ran their own tests, the outcomes of which again demonstrated the need for change. This led to a new regulation to be included in Amendment No. 3 to BS 7671, effectively requiring consumer unit enclosures in domestic households to be manufactured from non-combustible material (such as steel) or to be enclosed in a cabinet or enclosure constructed of non-combustible material. This new regulation is a welcomed step-change improvement in fire safety.

 

[LastManOnline]

This forum borks links to the IET site for reasons that are not obvious. However, the important bits from the article (to me at least) are quoted below:

Fires in plastic consumer units - a pattern of fires emerges

Back in 2011, the Fire Investigation Team identified an increase in the number and severity of fires involving consumer units. The team started looking carefully at the cause of those fires and established that there were issues with high resistance connections, where cables were not secured properly. This had the potential to lead to localised heating, arcing and, in some cases, to fires. There was also an emerging problem due to a large batch (over 1 million units) of non-compliant miniature circuit breakers (MCBs), which were subject to a product recall and which could also fail catastrophically.

Severe fires

The team were also seeing more fires that were spreading beyond the consumer unit and putting people’s lives at risk. Through a careful process of laboratory examinations and tests at Brigade consultant scientists Bureau Veritas, concern was raised about the flammability of the plastic enclosures of consumer units. Working closely with Electrical Safety First, more extensive tests of five plastic consumer units from different manufactures were carried out in 2012. These tests gave significant cause for concern due to the intensity of the fire and the levels of toxic smoke produced.

Location, location, location

A significant cause for concern when a consumer unit becomes involved in a fire is that it is commonly located on an escape route, for example, under the stairs or behind the front door. When this is combined with the fairly usual situation of coats, outdoor wear and other household items being stored nearby, once the fire starts, it often develops very quickly. London Fire Brigade was becoming extremely alarmed at the number of injuries occurring at such fires and the need for people to be rescued as they became trapped when the escape route was involved in fire.

A way forward

Working with Electrical Safety First, industry body BEAMA and other stakeholders, the process of presenting evidence for change began. A JPEL/64 project group was set up and ‘robust’ discussions about possible changes to BS 7671 (the Wiring Regulations) continued over several months.

Representatives from the Department of Communities and Local Government (DCLG) attended and raised concerns about possible changes. As a result of these concerns, DCLG commissioned independent tests at the Building Research Establishment (BRE). BRE tested two plastic and two metal consumer units and the subsequent report appeared to strongly support the need for change, stating:

“Both plastic consumer units caught fire and their casings became involved in the fire”… … “Both metal consumer units contained the fire within the unit” (Source: BRE report BD2890)

Also, some manufacturers ran their own tests, the outcomes of which again demonstrated the need for change. This led to a new regulation to be included in Amendment No. 3 to BS 7671, effectively requiring consumer unit enclosures in domestic households to be manufactured from non-combustible material (such as steel) or to be enclosed in a cabinet or enclosure constructed of non-combustible material. This new regulation is a welcomed step-change improvement in fire safety.

Many thanks for posting that info

 

[pc1966]

Many thanks for posting that info

No problem!

The article also mentioned the changes to have fire-resistant support for cables due to deaths of firefighters entangled in dropped cables, another Amendment 3 aspect, but as this thread is about metal CU I left that out.

 

[LastManOnline]

No problem!

The article also mentioned the changes to have fire-resistant support for cables due to deaths of firefighters entangled in dropped cables, another Amendment 3 aspect, but as this thread is about metal CU I left that out.

That's a pretty conclusive read. Interesting that the main issues are 1) loose connections (expected that) and ( 2) substandard materials like mcb, s (did, nt expect that)

 

[DPG]

That's a pretty conclusive read. Interesting that the main issues are 1) loose connections (expected that) and ( 2) substandard materials like mcb, s (did, nt expect that)

Yes there was a major problem with a batch of MCBs which were recalled. Very embarrassing for a major manufacturer. There will no doubt still be a lot out there.

 

[nicebutdim]

This forum borks links to the IET site for reasons that are not obvious. However, the important bits from the article (to me at least) are quoted below:

Fires in plastic consumer units - a pattern of fires emerges

Back in 2011, the Fire Investigation Team identified an increase in the number and severity of fires involving consumer units. The team started looking carefully at the cause of those fires and established that there were issues with high resistance connections, where cables were not secured properly. This had the potential to lead to localised heating, arcing and, in some cases, to fires. There was also an emerging problem due to a large batch (over 1 million units) of non-compliant miniature circuit breakers (MCBs), which were subject to a product recall and which could also fail catastrophically.

Severe fires

The team were also seeing more fires that were spreading beyond the consumer unit and putting people’s lives at risk. Through a careful process of laboratory examinations and tests at Brigade consultant scientists Bureau Veritas, concern was raised about the flammability of the plastic enclosures of consumer units. Working closely with Electrical Safety First, more extensive tests of five plastic consumer units from different manufactures were carried out in 2012. These tests gave significant cause for concern due to the intensity of the fire and the levels of toxic smoke produced.

Location, location, location

A significant cause for concern when a consumer unit becomes involved in a fire is that it is commonly located on an escape route, for example, under the stairs or behind the front door. When this is combined with the fairly usual situation of coats, outdoor wear and other household items being stored nearby, once the fire starts, it often develops very quickly. London Fire Brigade was becoming extremely alarmed at the number of injuries occurring at such fires and the need for people to be rescued as they became trapped when the escape route was involved in fire.

A way forward

Working with Electrical Safety First, industry body BEAMA and other stakeholders, the process of presenting evidence for change began. A JPEL/64 project group was set up and ‘robust’ discussions about possible changes to BS 7671 (the Wiring Regulations) continued over several months.

Representatives from the Department of Communities and Local Government (DCLG) attended and raised concerns about possible changes. As a result of these concerns, DCLG commissioned independent tests at the Building Research Establishment (BRE). BRE tested two plastic and two metal consumer units and the subsequent report appeared to strongly support the need for change, stating:

“Both plastic consumer units caught fire and their casings became involved in the fire”… … “Both metal consumer units contained the fire within the unit” (Source: BRE report BD2890)

Also, some manufacturers ran their own tests, the outcomes of which again demonstrated the need for change. This led to a new regulation to be included in Amendment No. 3 to BS 7671, effectively requiring consumer unit enclosures in domestic households to be manufactured from non-combustible material (such as steel) or to be enclosed in a cabinet or enclosure constructed of non-combustible material. This new regulation is a welcomed step-change improvement in fire safety.

When you think about it, plastic was an odd choice of material in the first instance. Other than being non-conductive I can't think of many reasons why it might have been used, other than cost. While safely installed distribution boards shouldn't be a fire risk, the fact is that this risk exists.

One thing that stuck me while reading through this thread is the aesthetic issue. Yeah I know it wont be of great importance to most electricians, but it would be a source of annoyance for many home owners (not going to be sexist and say women). Old metal BS3036 boards from the 70s or 80s generally look as good as the day they were installed, although a bit dated, but 90s plastic units are often yellowed with age and can look a bit manky and I reckon the current crop of boards should be less contentious for decor conscious homeowners.

There are probably plastics in existence that are considered to be non-combustible and which don't emit toxic fumes when heated, but I'm not aware of any manufacturer that tried this route. Bakelite would be a suitable choice, but I doubt many people would want to work with it!

 

[Dustydazzler]

Wouldn’t it be nice if you could get consumer units made of glass or other transparent non flammable material?

Might force a bit more pride in some people’s work.

There have been a few installations posted on here that look so good it is almost a crime to cover them up!

just leave the lid off ...

 

[DPG]

When you think about it, plastic was an odd choice of material in the first instance. Other than being non-conductive I can't think of many reasons why it might have been used, other than cost. While safely installed distribution boards shouldn't be a fire risk, the fact is that this risk exists.

One thing that stuck me while reading through this thread is the aesthetic issue. Yeah I know it wont be of great importance to most electricians, but it would be a source of annoyance for many home owners (not going to be sexist and say women). Old metal BS3036 boards from the 70s or 80s generally look as good as the day they were installed, although a bit dated, but 90s plastic units are often yellowed with age and can look a bit manky and I reckon the current crop of boards should be less contentious for decor conscious homeowners.

There are probably plastics in existence that are considered to be non-combustible and which don't emit toxic fumes when heated, but I'm not aware of any manufacturer that tried this route. Bakelite would be a suitable choice, but I doubt many people would want to work with it!

The yellowing is a good point. Early UPVC doors had the same problem. No excuse for it these days really, if good quality materials are used. Showers often seem to have the problem though.

 

[nicebutdim]

The yellowing is a good point. Early UPVC doors had the same problem. No excuse for it these days really, if good quality materials are used. Showers often seem to have the problem though.

I don't get to see many examples up close, but one other question in my mind was whether plastic units tend to become brittle or fragile with the passing of time?

 

[stewartrossinv]

It is through the in-depth investigations conducted by fire investigation teams after major fires that causal patterns in what are still relatively rare fires are discovered. London Fire Brigade is the largest in the UK (Scottish Fire and Rescue the second-largest), and its fire investigation teams found and drew national attention to the problems with fridge freezers and so on as already mentioned. I have no doubt that the issues they found are real.

In 2018-19 there were 11 deaths associated with a source of ignition being categorised as 'electrical distribution' out of a total of 164 fatalities in accidental dwelling fires in England (from data recorded on the national Incident Recording System and published annually by the Home Office, available at Fire statistics - https://www.gov.uk/government/collections/fire-statistics). It is not possible to know from the published information how many of these deaths resulted from overheating in consumer units, if any, or from wiring, trailing leads and other sources in the domestic environment. The details gathered by fire investigation teams in general remain confidential as in some cases investigations can result in legal action being taken.

The misuse of smokers materials accounted for 55 accidental dwelling fire deaths in England in 2018-19, so smoking remains a major cause of fire deaths.

I am not in any way doubting the importance of the contribution to fire safety that metal consumer units can and do make. To give just one example of the importance of legislative change in saving lives in fires, the change to the composition of furnishings in the 1980s (with the requirement for fire-retardant fillings and so on) has contributed to ongoing reductions in fire deaths and is responsible for saving hundreds of lives in the years that have passed. That along with the mandatory adoption of mains-powered smoke detection, which gives due warning of a fire to allow for escape from what otherwise could be fatal circumstances. When properties are protected by battery-powered smoke alarms it is heartbreaking for crews to find after a fire that the batteries were disconnected...