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?

 

[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?





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[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.----------------------------/media/1258/consumer-unit-connections.pdf

https://www.-----------------------...es/technical-e-news/consumer-unit-mythbuster/

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.----------------------------/media/1258/consumer-unit-connections.pdf

https://www.-----------------------...es/technical-e-news/consumer-unit-mythbuster/

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.