Metal Consumer units Giffnock

1. Why are these changes being made?

Further to several household fires involving plastic consumer units, investigations by the Glasgow fire brigade, has concluded that a key cause of the fires was substandard cable connections made by the Electrician within the consumer unit.

These resulted in overheating, which subsequently ignited the plastic enclosure.

The draft of Amendment 3 proposes changes to the fire protection regulations in BS 7671 Wiring Regulations. If approved, these changes will be incorporated in the 17th Edition of the Wiring Regulations, due to be published in January 2015. IET Chief Engineer Geoff Cronshaw interviews London Fire Brigade investigator Charlie Pugsley to find out more about the reasons behind these changes

2. What constitutes a substandard cable connection?

Many factors may contribute to a substandard connection. Some of these are inadequate tightening of conductors in the internal devices’ terminals or clamping the insulation of the cable rather than the conductor with the terminal screw.

In the third amendment, it is expected that the schedule of inspections for new installation work and condition report for existing installations, will require confirmation that all conductor connections within a consumer unit or distribution board are correctly located in terminals, and are tight and secure. Contactum would recommend that the manufacturer’s published tightening torques are adhered to.

3. What are the proposed changes? 

It is anticipated that when the third amendment of BS7671:2008 is published in January 2015 it is expected to state under new regulation 421.1.200: 

Within domestic (household) premises, consumer units and similar switchgear assemblies shall comply with BS EN 61439 3 and shall: (i). Have their enclosures manufactured from non-combustible material, or (ii). Be enclosed in a cabinet or enclosure constructed of non-combustible material and complying with Regulation 132.12. 

NOTE 1: Ferrous metal e.g. steel is deemed to be an example of a non-combustible material. 

NOTE 2:* the implementation date for this regulation is the 1st January 2016. This does not preclude compliance with this regulation prior to this date.

4. What is the intent of the new regulation?

The intent of regulation 421.1.200 is considered to be, as far as is reasonably practicable, to contain any fire within the enclosure and to minimise flames from escaping; caused mainly as a result of poorly installed connections. 

5. What is meant by ‘’non-combustible”? 

There is no published definition for “non-combustible” that aligns with the intent of regulation 421.1.200. Ferrous metal, e.g. steel is deemed to be one example of a non-combustible material that meets the intent of the regulation. 

6. What is meant by ‘within domestic (household) premises’? 

It is understood that Regulation 421.1.200 applies to consumer units and similar switchgear assemblies to BS EN 61439-3 inside all domestic (household) premises including their integral/attached garages and outbuildings or those in close proximity.

7. What impact will this regulation have? 

This would mean that eventually all new consumer units installed in UK homes, i.e. within domestic (household) premises, as defined in point 6 above; must have their enclosures manufactured from a non-combustible material, or be enclosed in a cabinet or enclosure constructed from a non-combustible material. Metal (Steel) enclosures are deemed to offer the best non-combustible characteristics.

8. Has Contactum been involved with these proposed changes?

Contactum have been closely involved in the development of these changes by providing expert industry liaison with interested bodies which including BEAMA (British Electrotechnical and Allied Manufacturers Association). Contactum are committed to delivering the highest quality products which afford maximum consumer safety.

9. When will Amendment 3 come into effect?

The third amendment to BS 7671:2008 will be issued in January 2015 and is intended to come into effect on 1st July 2015. Installations designed after 30th June 2015 are to comply with BS 7671:2008 incorporating Amendment 3, 2015. 

However, Regulation 421.1.200 does not come into effect until the 1st January 2016. This does not preclude compliance with this regulation prior to this date.

10. Does this mean all installed consumer units with plastic enclosures are a fire risk?

No, provided the consumer unit and its incorporated components conform to the relevant product standard(s), do not have latent defects, and have been installed correctly to the manufacturer’s instructions.

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ELECTRICAL INSTALLATION CONDITION REPORT (GLASGOW)

Electrical Condition Reports 

Faulty and old wiring is one of the main causes or electrical fires in the home in Glasgow. You can reduce the risk of a fire, and other electrical hazards such as electric shock by direct contact by checking the condition of your electrical wiring, switches, sockets, main consumer unit know as a fuse board and other accessories regularly.

How old is my electrical installation?

Signs that can help you tell the age of your electrical installation in your home include:

• Fixed cables coated in usually black vulcanised rubber (stopped being used in the 1960s).
• Fixed cables coated in lead or fabric sheath (used before the 1960s).
• A fuse box with a wooden back, cast iron switches, or a mixture of fuse boxes (used before the 1960s).
• Older round pin sockets (or light switches), braided flex hanging from ceiling roses, brown (or black) switches, or sockets mounted in or no skirting boards (used before the 1960s).
• Light switches on the walls or in bathrooms (used before the 1960s).

However old your electrical installation is, it may get damaged and will suffer from wear and tear. So you should get an electrician to check its condition at least every 10 years or or every 3 years if your a landlord and now the new regulations states overtime you have a change of tenancy.

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What is the aim of a condition report?

The five main aims of a Eicr condition report are:

1. Record the results of the inspection and testing to make sure the electrical installation is safe to be used until the next inspection (following any work needed to make it safe)
2. Find any damage and wear and tear that might affect safety, and report it
3. Find any parts of the electrical installation that do not meet the IEE Wiring Regulations
4. Help find anything that may cause electric shocks and high temperatures
5. Provide and important record of the installation at the time of the inspection, and for inspection testing in the future.

 Types of condition report

 In general, there are two types of domestic electrical installation condition report:

• Visual condition report - this does not include testing and is only suitable if the installation has been testing recently.
• Periodic inspection reports - this is what we would normally recommend, as it tests the installation and would find any hidden damage.

Glasgow

Replacement Consumer unit Glasgow

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17th Edition: Update for customers in the Glasgow and the surrounding areas october 21, 2015

Over the next year the electrical industry in the UK, faces Several changes to the electrical regulations. It has already started with the introduction of BS 7671: 2008(2015) - Amendment 3 to the 17th Edition of the IET wiring regulations - on 1st January 2015 and will continue through to 2016. It is important that electricians and electrical installers and electrical contractors understand what the amendment is and how it will affect their customers and there business

 So whats changed?

 BEAMA, the independent expert knowledge base and forum for the electrotechnical industry for the UK and across Europe, has said that the primary root-cause of fires in consumer units is loose electrical connections. Additionally, the London Fire Brigade has found that fires involving electrical consumer units have increased to approximately five incidents each week. It’s clear that a change needs to be made to protect consumers from potential harm. The London Fire Brigade LFB has been working with Electrical Safety First, BEAMA and other industry organisations to make edits to Amendment 3 requirements that will directly improve personal safety and quell the risk of residential fires.

What does it all Means? Glasgow 

To address this issue Amendment 3 will provide a degree of enhanced fire risk protection, requiring switchgear assemblies – including consumer units - to have their enclosures made from a suitable non-combustible material, or be installed in a cabinet or enclosure comprised from a suitable non-combustible material, for example steel. This is all covered within Chapter 42 with the addition of Regulation 421.1.201. MK Electric will be making the mandatory changes to their consumer units, using metal enclosures, which will be available at the end of March. This new range will be available alongside their MK Sentry insulated consumer unit portfolio. Enhanced fire safety is also referenced in the new Regulation 521.201, which outlines the requirements for wiring systems which are above escape routes, to be supported by fire-resistant fastenings and fixings. All cabling must be supported such that it cannot prematurely collapse when exposed to extreme heat. Once again there is a hint towards the use of metallic materials, although this is not prescribed. Amendment 3 also puts more responsibility on the installer. Chapter 41 examines the use of RCD protection on socket outlets. The regulation now requires RCD protection in accordance with regulation 415.1 for socket outlets up to 20A and for mobile equipment with a current rating not exceeding 32A for outdoor use, for all installations. However there is an exception, for socket outlets up to 20A, where the socket outlet is specifically labelled, or where a documented risk assessment determines that RCD protection is not necessary. Chapter 61 makes a new reference to ‘Skilled person (electrically)’ which has the added condition of the person being competent in inspection, testing and certification work. It also notes that supplies up to 100 amps have a new, more detailed schedule of inspections. Additionally, for installations greater than 100amps, a model list of items that require inspection during initial verification is provided in Appendix 6.

This list, along with a documented risk assessment of any permitted exceptions to the list must be appended to the Electrical Installation Certificate and the declaration signed. Dates to you need Know Over the next year and into 2016 there will be key dates that both manufacturers and installers need to keep in mind to comply with the updated regulation. • 1st January 2015: BS7671:2008+A3 was published.

Installations designed after this date may comply and be certified to these new standards or be designed and certified to BS7671:2008+A2 (for a maximum transitional period of 6 months) • 1st July 2015: BS7671:2008+A2 Installations designed after this date must comply fully with BS7671:2008+A3

 • 1st January 2016: Regulation 421.1.201 comes into full effect (this doesn’t preclude conformity beforehand) MK Electric is Ready​ MK Electric will shortly be announcing details of its new metal consumer unit range for compliance to regulation 421.1.201. The range will be available from the end of March. Additionally, MK Electric is offering electric installers and contractors the opportunity to take part in Continuing Professional Development Accreditation for Training to better understand the regulation. More specifically the session will address how the regulation affects installers, specific changes to be aware of and information they will need to counsel their clientele.

Consequentially, Amendment 3 to BS7671:2008 introduces a new regulation relating to the enhancement of Fire Safety, as follows: Regulation 421.1.201 – Protection against thermal effects – Consumer Units Within domestic (household) premises, consumer units and similar switchgear assemblies shall comply with BS EN 61439 3 and shall: Have their enclosure manufactured from a non-combustible material, or Be enclosed in a cabinet or enclosure constructed of non-combustible material and complying with Regulation 132.12 Amendment 3 was published on 5th January 2015 and will apply to all Electrical installations designed after 1st July 2015; however Regulation 421.1.201 will not be mandatory until 1st January 2016.

Metal Consumer Unit Regulation 2016 Amendment 3

Below is the new amendments for the 17th edition electrical installation regulations

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NEW NUMBERING SYSTEM

The Third amendment recognises UK only regulations and these are now identified by a new numbering system. Regulations with a .100 number are CENELEC requirements and those with a .200 number are specific
to the UK.

PART 2 - Definitions

Definitions have been expanded and modified, including the introduction of some new symbols. A list of abbreviations used in the Regulations has been added. The definition of ‘competent person’ has been removed and it has been replaced with ‘instructed person (electrically)’ and ‘skilled person (electrically)’. These changes have been reflected throughout the wiring regulations.

CHAPTER 41 - Protection against electric shock


There is now a requirement for RCD protection for socket-outlets up to
20A for all installations, however exceptions are permitted for:
a specific labelled or otherwise suitably identified socket-outlet provided for connection of a particular item of equipment, or
where, other than for an installation in a dwelling, a documented risk assessment determines that the RCD protection is not necessary
Maximum earth fault loop impedances given in tables 41.2, 41.3, 41.4 and 41.6 have been revised to take account of the Cmin factor. Cmin is the minimum voltage factor to take account of voltage variations depending on a number of considerations.

CHAPTER 42 - Protection against thermal effects

Due to the number of consumer unit fires reported within domestic premises, Regulation 421.1.201 (UK only) has been added and

requires consumer units and similar switchgear to have their enclosure manufactured from non-combustible material or be enclosed in a cabinet or enclosure constructed of non-combustible material and complying with Regulation 132.12.
Please note: This regulation will be implemented on 1st January 2016 to allow for manufacturers to ensure an adequate supply of suitable cabinets or enclosures is available.

CHAPTER 51 - Common rules

Section 551 concerning compliance with standards requires all equipment to be suitable for the nominal voltage and also requires certain information to be noted on the Electrical Installation Certificate.

CHAPTER 52 - Selection and erection of wiring systems

A new regulation 521.200 (UK only) has been included giving requirements for the methods of support of wiring systems in escape routes.
The regulations concerning selection and erection of wiring systems have been re-drafted. Reference to “under the supervision of a skilled or instructed person” has been removed.

CHAPTER 55 - Other Equipment


A new section 557 Auxiliary Circuits is included. All auxiliary circuits are
defined in Part 2.

SECTION 559 - Luminaires and lighting installation

Requirements for outdoor lighting installations and extra low voltage lighting installations have been moved to new Sections 714 and
715 respectively.

PART 7 - Special Installations or Locations Section 701 locations containing a bath or shower

There is now a requirement for RCD protection to be provided for: low voltage circuits serving the location
low voltage circuits passing through zones 1 and 2 not serving the location.
Appendix 3 - Time/current characteristics of overcurrent protective devices and RCDs
This includes changes in connection with maximum earth fault loop impedance to take account of the Cmin factor given in CLC/TR50480:2011.

APPENDIX 6 - Model forms for certification and reporting

The schedule of inspections (for new work only) has been replaced by examples of items requiring inspection during initial verifications (which must be appended to the Electrical Installation Certificate).
A small number of changes to the Electrical Installation Condition Report and associated notes have been made, including a requirement to carry out an inspection within an accessible roof space where electrical equipment is present in that roof space.
This summary is not a definitive guide to all the changes introduced by Amendment 3 and contractors will be required to demonstrate a full and comprehensive understanding of AMD 3 at their assessment visit. 

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Cosumer Unit / Fuse Board Changes In Glasgow

BS 7671 Amendment 3 & changes to 
Consumer Units

As you may be aware there are changes being made to the wiring regulations BS 7671 with Amendment 3 which is due to be published in January 2015. One of these changes is expected to involve consumer units installed in household premises and is focused on the material their enclosures are manufactured from.

What is driving the changes?

Investigation into several fires involving plastic consumer units, by the Strathclyde Fire Brigade, has concluded that a key cause of the fires was substandard cable connections made by the Electrician. These resulted in overheating, which eventually ignited the plastic enclosure.

How has Hager been involved with the proposed changes to consumer units?

As a result of the investigations into consumer unit fires, proposals have been made for changes to the Wiring Regulations. Hager has been closely involved in the development of these changes by providing expert industry liaison with interested bodies including;Strathclyde Fire Brigade, Government and the Joint IET/BSI Technical Committee JPEL/64 which has the responsibility for the content of BS 7671 (17th Edition Wiring Regulations).

Anticipated new regulation

The new Regulation 421.1.201 is expected to state:
Within domestic (household) premises, consumer units and similar switchgear assemblies shall comply with BS EN 61439 3 and shall:
I. Have their enclosures manufactured from non-combustible material, or
II. Be enclosed in a cabinet or enclosure constructed of non-combustible material and complying with Regulation 132.12.
Note 1: Ferrous metal e.g. steel is deemed to be an example of a non-combustible material.
Note 2:* the implementation date for this regulation is the 1st January 2016. This does not preclude compliance with this regulation prior to this date.

What impact will this have?

This would mean that eventually all new consumer units installed in UK homes, i.e. within domestic (household) premises must have their enclosures manufactured from a non-combustible material, or be enclosed in a cabinet or enclosure constructed from a non-combustible material. This is likely to result in an increased use of metal enclosures. 

What is meant by ‘within domestic (household) premises’?

It is understood that Regulation 421.1.201 applies to consumer units and similar switchgear assemblies to BS EN 61439-3 inside all domestic (household) premises including their integral/attached garages and outbuildings or those in close proximity.

When will Amendment 3 come into effect?

The third amendment to BS 7671:2008 Requirements for Electrical Installations will be issued in January 2015 and is intended to come into effect on 1st July 2015. Installations designed after 30th June 2015 are to comply with BS 7671:2008 incorporating Amendment 3, 2015.
However, Regulation 421.1.201 does not come into effect until the 1st January 2016. This does not preclude compliance with this regulation prior to this date.

electricians southside glasgow

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Smoke Detectors and Co Alarms to become legal requirements for landlords

Landlords in England and Scotland will be required by law to install working smoke and carbon monoxide alarms in their properties from October 2015, it has been announced.

According to Housing Minister Brandon Lewis the move will help prevent up to 36 deaths and 1,375 injuries a year after a consultation showed strong support for the measure.

Fire and rescue authorities in Glasgow are expected to support private landlords in their own areas to meet their new responsibilities with the provision of free alarms, with grant funding from the government.

Lewis explained that it is part of wider government moves to ensure there are sufficient measures in place to protect public safety, while at the same time avoiding regulation which would push up rents and restrict the supply of homes, limiting choice for tenants.

‘In 1988 just 8% of homes had a smoke alarm installed but now it’s over 90%. The vast majority of landlords offer a good service and have installed smoke alarms in their homes, but I’m changing the law to ensure every tenant can be given this important protection,’ said Lewis.

‘But with working smoke alarms providing the vital seconds needed to escape a fire, I urge all tenants to make sure they regularly test their alarms to ensure they work when it counts. Testing regularly remains the tenant’s responsibility,’ he added.

These alarms should be fitted by a qualified electrician or electrical contractor

According to Communities Minister Stephen Williams it will help to create a bigger, better and safer private rented sector. ‘A key part of that is to ensure the safety of tenants with fire prevention and carbon monoxide warning. People are at least four times more likely to die in a fire in the home if there’s no working smoke alarm,’ he said.

‘That’s why we are proposing changes to the law that would require landlords to install working smoke alarms in their properties so tenants can give their families and those they care about a better chance of escaping a fire,’ he added.

The proposed changes to the law would require landlords to install smoke alarms on every floor of their property, and test them at the start of every tenancy. Landlords would also need to install carbon monoxide alarms in high risk rooms such as those where a solid fuel heating system is installed.

Those who fail to install smoke and carbon monoxide alarms would face sanctions and could face up to a £5,000 civil penalty. This would bring private rented properties into line with existing building regulations that already require newly built homes to have hard wired smoke alarms installed.

New regulations will be laid in Parliament to require landlords to install smoke and carbon monoxide alarms in their properties, and are expected to come into force, subject to Parliamentary approval, on 10 October 2015.

The allocation of funding to fire and rescue authorities to offer free smoke and carbon monoxide alarms to local landlords will be announced shortly.

The British Property Federation said the crackdown was necessary to force the small number of landlords who did not install alarms in their properties to bring them up to standard. It added that although most landlords do everything necessary to ensure the safety and comfort of their tenants, making the installation of carbon monoxide and smoke alarms compulsory will give tenants peace of mind and provide clarity to landlords. 

The BPF recommended that the obligation on landlords and their agents should be to ensure that there are working detectors at the time the tenancy starts. There should be an obligation on tenants, however, to maintain and test the alarms and to report any faults.

'It is quick, cheap and easy to install these pieces of equipment, so making them mandatory makes sense, and should weed out those who are currently putting their tenants at risk. While the majority of landlords adhere to best practice and ensure that fire and smoke detectors are installed in every rented property they own, we feel that landlords and tenants can only benefit from this additional safeguard,' said Ian Fletcher, director of policy at the British Property Federation.

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ELECTRICAL CONTRACTING 101

(see blog post for the heading lols)

Here i have for you a blog about electrical consumer units you know the box that when you have no power it has usually tripped or the fuse wire needs replaced.....enjoy


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Warning: To complete electrical works you must comply with Electrical Regulations.

Please also see our project on the New Wiring and Cable Colours.

All cables and connections to the consumer unit must be checked and tested by a qualified electrician. Do not attempt removal or replacement unless you are you are qualified to Part P regulation standards. It is also an offence to interfere with the seals on the electricity meter.

Please see our project on Part P of the building regulations for information on DIY Electrical Installation.

The Consumer Unit

The modern consumer unit is the centre, or heart, of the wiring system in the home. The unit distributes the electricity, via fuses of one kind or another, to the different circuits in the house. The older fuse wires are being replaced gradually by their modern equivalent, the MCB or miniature circuit breaker.

Consumer unit for installation with rcd's

Different Types of Consumer Unit

We will deal with the two main types of consumer unit found in the home today.

Single Load Board

The first one is a single load fuse board where the power coming in is taken through a double pole switch to a live bus bar. Each fuse, or MCB, is clipped onto a DIN bar and the "teeth" of the bus bar are inserted into the MCB's. The cables to the house circuits are connected to the other side of the MCB's. All of this is explained more thoroughly when we deal with the second type of unit, which is the split load unit. The photographs are of a split load fuse board. The ordinary consumer unit is exactly the same in principle without the RCD.

Consumer Unit

Under the 17th edition regulations it is required that every socket is protected by an RCD. This can be done in 3 ways. 

A consumer unit can use an RCD as the main switch. This will protect all circuits but if the RCD trips, so do all circuits. 

A dual RCD consumer unit can be fitted. This unit has one main switch, two RCDs and each circuit has it's own MCB. This allows the circuit to be divided into two, usually one upstairs, one down. This protects all areas including showers and cookers, but if one trips the other will ensure at least some lights and some sockets still work.

An RCBO consumer unit has one main switch but each circuit is protected by an RCBO which is a combination of an MCB and an RCD. This allows protection in full for all individual circuits and if one trips, all others will still work. As this option is expensive it is only usually used where space is tight for the enlargement of a consumer unit as has to happen when updating to a dual RCD unit.

Just as a matter of interest, DIN stands for Deutsche Industrie Norm and, originating in Germany, is any of a series of technical standards, used Internationally, to designate electrical connections, film speeds and paper sizes. Shown in the consumer unit casing above, it is a metal, pressed bar, to which the MCB's clip. They simply push on via a spring loaded lock at their back.

Split Load Board

A split load board is designed for total safety and incorporates an RCD (Residual Current Device, shown as E in the picture above) as well as the double pole switch (D).The split board shown here has one RCD and is a simple version to show the user how the board works. 

An RCD is a manually operated isolator switch, but it is also an automatic safety device that will trip and cut off as soon as it senses an earth fault. There are a number of different ratings for current and sensitivities to current leakage available, so you will need to understand which are the appropriate ratings for your home. RCD's also work by detecting an imbalance between the Live and the Neutral conductors and this feature is a requirement for all Class 2 double insulated equipment.

As they are very sensitive, it is not practical to fit one RCD to protect the whole house. If a fault develops on one circuit, all circuits would be switched off immediately...This would, most often, leave you in the unnecessary position of having no lights or power. Because of this it actually contravenes the most recent (16th Edition) wiring regulations. This is easily prevented by using an RCD in conjunction with a main, double pole isolating switch so that it protects only some of the more vulnerable circuits. This then becomes a split load consumer unit and is shown above. The key to this photo is..

• A: Neutral terminal block for the main isolating switch side of the unit
• B: Neutral terminal block for RCD side of the unit
• C: Earth terminal block (takes both sides of unit)
• D: Main double pole isolating switch
• E: Generally 80 - 100 Amp RCD with 30mA (milliamp) sensitivity
• F: Neutral link cable from Main switch to terminal block
• G: Live feed from main switch to RCD
• H: Neutral link cable from main terminal block to RCD
• I: Neutral link cable from RCD to RCD neutral terminal block

RCD's

The use of RCDs is necessary, on two occasions, to meet the wiring regulations. The first of these is to protect any socket which may be reasonably expected to supply equipment outside the house (Strimmers, lawn mowers, hedge trimmers, pond pumps, sheds, lights etc etc). This rule pretty much covers every single socket in the house so the ring main should be placed on the RCD protected side of the consumer unit.

RCDs have a test button which creates an earth leak with a resistor, and it is usually recommended that they are tested once a month. An information label near the consumer unit explains this The resistor passes more current than that required for tripping, and the duration of the test is not limited, so testing in this way does not provide proof that the unit is working to specification. RCDs can also be switched off manually and can take the place of the isolator switch in the consumer unit, if they break live and neutral.

The second condition applies to any circuits where an earth fault current is not sufficient to blow the fuse, or trip the switch, in the designated time allowance made in the regulations. This generally applies to higher Amp rated appliances (showers, cookers etc) but it should always be checked with an electrician as to which circuits need to be placed on the RCD side of the consumer unit.

MCB's

The Current ratings which MCBs are designated to deal with are now conforming to the international equivalent of our old imperial ratings. This standard is called the Renard current rating and supercedes the imperial ratings as far as MCBs are concerned. A 5 amp fuse can be replaced with a 6 amp MCB. A 15 amp fuse becomes a 16 amp MCB, a 20 amp fuse can be a 20 amp MCB, 30 amp fuse = 32 amp MCB and a 45 amp fuse must now be a 40 amp MCB.

Consumer Unit with MCB and main double pole isolation switch

Consumer Unit with MCB's and Bus Bar

Top left shows the mains double pole isolating switch and an MCB clipped into place on the DIN bar. Top right shows two MCBs and the bus bar. When the MCBs are clipped onto the DIN bar, the bus bar is inserted into the live terminal at the bottom of the MCB. When screwed tight this gives live feed to all the MCBs.

Main double pole isolation switch on din bar

live and neutral coming into the main double pole switch from the meter and earth terminal block

Top left shows the live (K) and neutral (J) coming into the main double pole switch from the meter. These cables are called tails, and in this instance, with this type of unit, are 16mm cables. This will vary and you should always check with a qualified electrician. Top left shows the earth cable from the meter (L). This screws into the earth terminal block.

Live connected to MCB with neutral going to RCD neutral terminal block

Top right of the above image shows how a circuit cable is introduced to the unit. In this case it is a 2.5mm cable for the ring main. The live (O) is fixed into the top of an MCB on the RCD side of the unit, while the neutral (M) goes to the RCD neutral terminal block. The earth (N*) (which has been left unsheathed for clarity ). Each circuit cable is fed into the consumer unit and connected to an MCB of the appropriate rating.