About the 18th Edition BS7671

A new version of the Wiring Regulations will come into effect on the 1st January 2019…

The 18th Edition of BS7671:2018 Requirements for Electrical Installations (to give it its full title) introduces some significant changes to the previous 17th Edition of BS7671.

This new book if all goes according to plan with the IET will be available from the 1st July 2018 onwards and as I said the actual 18th Edition Wiring Regulations will apply from the 1st January 2019. This means that any ongoing or future building projects that were started or designed before this date will need only to comply with the current 17th Edition.

This means that the 17th Edition may still be relevant for years to come. So, there’s no need to dash off and pass the 18th Edition on the 1st of January 2019, although it’s always a good idea to be ahead of the curve when it comes to job hunting, promotion etc. I’m also pretty sure that the likes of the NICEIC etc will insist that QS’s will be 18th Edition qualified as soon as possible.

Going off the draft version of the 18th Edition there could be more than 250 additional pages. Giving the 18th more than seven hundred ‘fun filled’ pages with many alterations and additions to get your head around.

Briefly as I’m going to go into more detail in later posts we have…

Minor changes within Part 1 Scope, object and fundamental principles and within Part 2 Definitions there will also be some modifications.

Part 4 Protection for safety sees some major and small alterations within key Chapters. Table 41.1 for example ‘disconnections times’ gets an upgrade, as do many other important areas. There’s also a surprise coming as far as equipotential bonding is concerned and there’s a new addition to Part 4, Chapter 46 Devices for isolation and switching

Part 5 Selection and erection of equipment  also has many changes and new regulations within its individual Chapters, but no new Chapter.

They have been tinkering with the numbering system in Part 6 Inspection and testing by deleting and moving things around just because they can.

In Part 7 Special installations and locations many of the important Sections have suffered minor changes and there is a bit of a rethink regarding the use of PME supplies in Section 722 Electric vehicle charging installations. There’s also a new Section 730 Onshore units of electrical connections for inland navigation vessels.

We have a whole brand new Part 8 Energy efficiency as we now have to consider how installations perform as far as consumption of energy is concerned and whether and how it can be reduced.

Six Appendices have had alterations with a big chunk from Appendix 14 Determination of prospective fault current being moved to Appendix 3 Time/current characteristics of overcurrent protective devices and RCDs.

So all in the 18th Edition looks like fun. Don’t forget to have a look at our Wiring Regulations online training options including the new 18th Edition online course.

Early Bird 18th and Study Plus Combo “Pay once Pass TWICE!”: Details

More soon….

 

 

 

 

 

 

Electric Shocks

How an electric shock occurs…

An electric shock occurs when a person becomes part of a circuit, with current entering the body at one point and leaving it at another.

The two methods of receiving an electric shock are…

Coming into contact with a normally live part (i.e. touching the live terminals within a consumer unit) or by touching a non-live part that has become live due to a fault in an electrical installation such as the case of a washing machine that has become live due to an earth fault.

How serious the shock you receive depends on your physical condition, and general health.

The amount of current present – “it’s the current that causes the problem and not the voltage.”

The path the current flows through your body and the length of time exposed to the current present.

So, remember, Voltage hurts but Current can kill

Non-lethal electric shocks occur when…

More than 3 milliamps (0.003A): You’ll receive a painful shock
More than 10 milliamps (0.01A): You’d feel muscle contraction
More than 20 milliamps (0.02A): This would really hurt and is considered severe electric shock
More than 30 milliamps (0.03A): You’d receive lung paralysis – usually temporary

Lethal electric shocks are…

More than 50 milliamps (which is only 0.05A): Possible ventricular fibrillation ‘heart flutter’ which is usually fatal.
100 milliamps (0.1A) to 4 amps: Certain ventricular fibrillation and definitely fatal
Over 4 amps: Heart paralysis / severe burns and very fatal – electric chair!

If you see someone receiving an electric shock
Isolate the person from the electrical source. Turn off the electricity if possible, or move the person using a non-conducting material such as wood.
Never touch the person receiving an electric shock or you too could receive one.

Other first aid will quite likely be needed

Five Knowledge Traits of a Great Domestic Electrical Installer

#1: Knowledge of Electricity…

A good understanding of the basic principles of electricity is essential, from Ohm’s Law and resistors in series and parallel to power calculations and transformer theory. Including a good working knowledge of cable and protective conductor sizes as well as selecting protective devices their rating and types including the use of RCDs.

 

#2: Knowledge of the trade and its regulatory requirements…

Be fully conversant with the Requirements for Electrical Installations – BS 7671 and to stay up to date with any alterations amendments or newer versions. There’s also the Building Regulations…

Part A: Structural
Part B: Fire Detection / Prevention
Part E: Sound Penetration
Part F: Ventilation
Part L: Energy Conservation
Part M: Disabled Access and Use
Part P: Electrical Installation Requirements

Plus – Health and Safety at Work Act, Electricity at Work Regulations, Provision and Use of Work Equipment, PPE, Safe Isolation etc

Basically everything that’s required in order to work safely

#3: Knowledge of domestic installations…

The types of incoming supplies, earthing and bonding. What circuits can be used, rings or radials and where and what for. Cable sizes, protective device ratings and uses, and be able to show through calculations the reasons why any particular type or size of device or cable is used. Plus being able to wire anything that may be required in the home, from rings for sockets, radial circuits for lighting, including two-way and intermediate switches, showers, cookers, immersion heaters, alarm feeds, smoke detectors, and central heating system (Y and S Plan).

#4: Knowledge of Electrical Testing…

Being able to verify that your work is safe and compliant with the Wiring Regulations is without a doubt the most important task involved in any domestic electrical installation work. And that’s why it’s essential that you can inspect and test any work you undertake. From the initial inspection and all the way through the dead testing to the live testing and then completing the relevant certificate correctly.

#5: Knowledge of Business…

How you run your business and how the world sees it will ultimately decide whether you’re a success or not. Being professional and joining a Domestic Installers Scheme (NAPIT, NICEIC, Stroma etc). Finding, pricing and billing for your work, building customer referals and recommendations are often things that are overlooked but a vitally important if you want your business to grow.

Take a look at our new Domestic Installers Workshop at www.partPtrained.co.uk for lots more information on the…

Five Knowledge Traits of a Great Domestic Electrical Installer

“Professional Domestic Electrical Installer’s Training with Seven Day Tutor Support – Start Today!”

Includes: Three City & Guilds Courses and a Domestic Installer’s online Workshop visit

https://.partptrained.co.uk

Protective Bonding Conductor Sizes

Sizes of main Bonding Conductors…

This can be confusing as the size of the main bonding conductor differs depending on the type of supply.

In a TN-S or TT system the main bonding conductor is in relation to the size of the main earthing conductor which is dependant on the size of the incoming line conductor.

e.g. A 25mm line supply conductor requires a 16mm main earth conductor (see table 54.7 BS 7671). The main bonding conductor in a TN-S or TT supply system must be at least half the cross sectional area of the main earth conductor (see 544.1.1 BS 7671).

Half the size of 16mm is 8mm but there’s no such cable size so we’ll go up to the next available size, which is 10mm for the main bonding conductor.

In a TN-C-S the main bonding conductor size is dependant on the size of the incoming neutral conductor (see 544.1.1 second paragraph and Table 54.8 BS 7671).

e.g. A TN-C-S supply has a 25mm neutral conductor, which is less than 35mm (Table 54.8) so a 10mm main bonding conductor is required.

Either way it’s 10mm.

 

 

Domestic Consumer Units

Consumer units in new and modern domestic installations should contain Residual Current Devices ‘RCDs’ as well as circuit breakers. Either as combined RCD/circuit breaker devices ‘RCBOs’ which can get a bit expensive or alternatively and less expensive through the use of split load boards with usually two RCCBs protecting multiple circuit breakers.

Since January 2016 and the introduction of Amendment 3 to the 17th Edition of BS7671…

All domestic consumer units must be made of a non-combustible material or enclosed in a cabinet made of a non-combustible material.

The layout of a split load consumer unit – the supply enters the unit via the double pole Main Switch which can be used to isolate the consumer unit/installation. From the out going side of main switch we have a Line and Neutral supply to the incoming side of each RCCB which in turn connects to the neutral bars and supplies the individual circuit breakers via the copper busbar at the bottom.

Things to note. The current rating on the Main Switch usually 100A is not the ‘tripping current’ of the device – as it offers no overload protection. The rating represents the safe switching current of the device only. Also on the RCBOs the current rating of usually 80A or 63A is also just the switching capacity of the device and the 30mA is the ‘tripping’ current of this RCD device.

Completed cosumer units should also have any blanks in place where needed and there should be no holes in the front, bottom or sides that are big enough to stick a finger in. On the top of the consumer unit there should be no holes larger than 1mm in diameter after completion. Stickers informing of the RCD test procedure should be in place as should any inspection and testing notices.

PVC Cables Concealed in Walls

The most common cable found within a domestic electrical installation is the PVC insulated and sheathed Twin and CPC cable – also known as Twin and Earth. A PVC three core and CPC is also used on two-way lighting circuits, smoke detector interlinks, fans with timers and also central heating thermostat connections etc.

Cables should always run within prescribed ‘cable zones’ which are 150mm down from the ceiling, 150mm at each side of any corners within a room and horizontally or vertically to any point or accessory.

When run below the surface of the wall PVC cables won’t react chemically with the plaster so there is no need to provide any protection unless it’s required mechanically (steel conduit, trunking, capping…)

If no mechanical protection is used and the cables are less than 50mm from the surface of the wall, which is usually the case then additional protection with a 30mA RCD must be used – see Regulation 522.6.202.

 

What’s an Electrician?

 

What makes an electrician?

The Electricity at Work Regulations 1989 (EAWR) – Regulation 16 states that…

“No person shall be engaged in any work activity where technical knowledge or experience is necessary to prevent danger or where appropriate injury, unless he/she possesses such knowledge or experience, or is under such a degree of supervision as may be appropriate having regard to the nature of the work.”

In other words you should not be doing any electrical work unless you know how to do it safely. If you don’t know how to do it safely then you should be supervised by someone who does.

BS 7671 gives guidance on how to comply with the Electricity at Work Regulations and helps with Regulation 16 by providing the following three definitions…

Skilled Person (electrically): Person who possesses, as appropriate to the nature of the electrical work to be undertaken, adequate education, training and practical skills, and who is able to perceive risks and to avoid hazards which electricity can create.

Instructed Person (electrically): Person adequately advised or supervised by a “skilled person” to enable that person to perceive risks and to avoid hazards which electricity can create.

Ordinary Person: Person who is neither a skilled person or an instructed person.

As you can see from the definition of a skilled person that experience alone is not proof of competency. Experience needs to be combined with the appropriate qualification(s) as evidence of having the technical knowledge and the practical skills required in order to recognise the risks and avoid the hazards involved when working with electricity.

For example, a domestic electrician may not have sufficient experience to work safely in a heavy industrial environment as an industrial electrician, and vice a versa but they may have the same qualifications ie C&G 2357/2365 17th Edition and Inspection and Testing (Initial and Periodic) etc.

“Electrician is a vague term for a person who complies through the guidance of good old BS 7671 with the Electricity at Work Regulations 1989 and has the qualifications and experience to demonstrate that they are a ‘Skilled Person’.”

NOTE: The Electricity at Work Regulations 1989 is a statutory document (ie the Law) and you can be prosecuted, leading to fines or even imprisonment for non compliance.

Electric Shocks

How an electric shock occurs…

Current travels through conductors within a closed circuit. The conductors could be made of copper such as in a cable, other metals, water or in the worst case the conductor can become the human body.

An electric shock occurs when a person becomes part of a circuit, with current entering the body at one point and leaving it at another.

The two methods of receiving an electric shock are…

Coming into contact with a normally live part (i.e. touching the live terminals within a consumer unit) or by touching a non-live part that has become live due to a fault in an electrical installation such as the case of a washing machine that has become live due to an earth fault

How serious the shock you receive depends on your physical condition, and general health.

The amount of current present – it’s the current that causes the problem and not the voltage.

And the path the current flows through your body and the length of time exposed to the current present.

So, remember, Voltage hurts but Current can kill

Non-lethal electric shocks occur when…

More than 3 milliamps (0.003A): You’ll receive a painful shock
More than 10 milliamps (0.01A): You’d feel muscle contraction
More than 20 milliamps (0.02A): This would really hurt and is considered severe electric shock
More than 30 milliamps (0.03A): You’d receive lung paralysis – usually temporary

Lethal electric shocks are…

More than 50 milliamps (which is only 0.05A): Possible ventricular fibrillation ‘heart flutter’ which is usually fatal
100 milliamps (0.1A) to 4 amps: Certain ventricular fibrillation and definitely fatal
Over 4 amps: Heart paralysis / severe burns and very fatal – electric chair!

If you see someone receiving an electric shock
Isolate the person from the electrical source. Turn off the electricity if possible, or move the person using a non-conducting material such as wood.
Never touch the person receiving an electric shock or you too could receive one.

Other first aid will quite likely be needed

The 17th Edition Has Still Got Legs

The 17th Edition has still got legs…

Although the 17th Edition of BS 7671 is due to be replaced by the 18th Edition in January 2019, the 17th Edition is relevant today and will still be as relevant long after that date.

The main reason for this is…

Any installation designed before January 2019 would only need to comply with the 17th Edition. Meaning, you could be installing to the 17th Edition well into the 2020s and even beyond.

And for anyone already with the 17th Edition including Amendment 3…

There’s usually an overlap period, as electricians are not expected to drop everything and head for the exam centres on the 1st of January 2019.
Plus, going off experience, the City & Guilds 2382-19? exam won’t be available till well after that date.

Qualified Supervisors, you’d probably be expected to update sometime during 2019 and within 2020 at the latest. The same goes for small business owners and JIB electricians – agency sparks, subcontractors etc. ‘Don’t forget to update your JIB card’.

It’s easier…

What I mean is, I’ve recently been going through the draft copy of BS7671 18th Edition and apart from it having around two hundred and fifty more pages (50% bigger). There’s plenty of new regulations, including a whole new part, ‘Part 8 – Energy Efficiency’.

“I won’t bore you with all the details of the new book for now, I’ll save that for a future post.”

This means that they are not just going to have to rewrite the whole exam for the 18th Edition, mainly to include the addition of Part 8, but the whole exam will have to be reconfigured.

This could mean a re-jig of the current exam with fewer questions on say Parts 4 and 5 or even the possibility of additional questions, raising the number of exam questions to above the current sixty.

The 18th Edition exam will be based on a bigger book with more pages to reference than the 17th Edition and in all likelihood, there will be more questions too.

However, there’s usually an update exam which will be opportunity for people who already have the 17th Edition up to Amendment 3 to take a shorter exam that’s just based on the changes introduced to the 18th Edition of BS 7671

In my opinion, passing the 17th and then the passing the 18th Edition update exam will be easier than completing the whole of the 18th Edition exam in one go.
So, the 17th Edition will be relevant well after January 2019, and passing it before then will make it easier to get your 18th Edition when the time comes.

Competent Person’s Schemes

In order to be able to sign off your own work under Part P you would need to be a member of a domestic installers competent person’s scheme ie with NAPIT, Elecsa, NICEIC etc.

To join a competent persons scheme you would need to demonstrate to them that you have sufficient knowledge and experience to complete your work safely and in compliance with any applicable regulations. The basic qualifications that could be used as evidence of knowledge are the 17th Edition Wiring Regulations C&G 2382, the Building Regulations C&G 2393 and an Inspection and Testing qualification such as the C&G 2392 ‘Initial Verification and Certification’.

These combined with evidence of experience such as references as well as work you have completed that they can examine could be enough to secure your place on a competent person’s scheme. Although installers with little experience may be required to complete a more formal – apprentice type course and qualification such as the old C&G 2365 up to at least level 2.

Our online courses at partptrained.co.uk will provide the qualifications for the Building Regulations C&G 2393 and the Inspection and Testing C&G 2392 and our online workshop contains the domestic electrical installation theory training needed to be a good competent domestic installer.

We also provide the online training and the C&G 2382 exam for the 17th Edition Wiring Regulations at our online training website: www.the-regs.co.uk

If you ring round the competent person’s scheme providers – the NICEIC may require more experience, but Elecsa and NAPIT are usually very helpful.