The 18th Edition Wiring Regulations

The 18th Edition Wiring Regulations and the use of SPD’s (Surge Protection Devices) for Protection of Transient Over voltages from Lighting Strikes and Supply Switching Origins.

Previously the requirements to provide surge protection devices or not was rather complex, requiring a classification code to be applied relating to the number of thunderstorm days at a location. This has all been removed and the 18th Edition now requires protection against transient over voltage (Lighting strike) to be provided where the consequences are:-

  • results in serious injury to, or loss of, human life, or; -results in interruption of public services/or damage to and cultural heritage, or; -results in interruption of commercial or industrial activity, or;
  • affects a large number of co-located individuals. SPDs are now required as part of BS 7671:2018 unless a risk assessment is performed and determines otherwise. Should a risk assessment NOT be performed then protection against transient overvoltage (an SPD) IS REQUIRED TO BE INSTALLED. These are installed either within the consumer unit or as a stand-alone unit adjacent to the consumer unit/within a set distance from the consumer unit

Single dwelling units however also require an assessment as to whether the total value of the installation and equipment therein justifies the inclusion of such protection, it should be noted that modern living in dwellings does encompass a large number of high value items such as Smart TV’s, Satellite receivers, Computer equipment, Wireless Broadband equipment, Boilers and controls, Games consoles, Washing machines, Fridge Freezers and other electrical appliances – not to mention the value of the entire electrical installation itself.

Some Home insurance may require an installation to adhere to the current edition of the wiring regulations thus an omission of an SPD could invalidate the insurance in the event of a lightning strike. It should be noted that not all premises would be required to have an SPD installed providing the risk assessment is carried out.

The 18th Edition Wiring Regulations and Additional Protection against Fire

With the 18th Edition of the Wiring Regulations published in July 2018, the new regulations are enforceable from 1st January 2019.

All new install work undertaken from 1st January 2019, unless designed prior to this date, has to comply with BS 7671:2018.

EICR (Electrical Installation Condition Report) fixed wiring inspections done from 1st January 2019 will have to be completed to the new 18th edition wiring regulations standard, as set out in BS 7671:2018.

Electrical Fires

Electrical fires continue to be a recurring danger in the UK, with recent events shockingly highlighting the risks.

The 18th edition wiring regulations (BS7671) sets out requirements for electrical installations in the UK, including requirements for protection of persons, livestock & property against the risk from fires that may be generated & propagated in electrical installations.

From a wiring regulations point of view, the definition of danger includes risks to persons, livestock and property during use of electricity in electrical installations.

Arc Fault Detection Devices (AFDDs) have an important role to play in protecting people and property against the risks of fire.

AFDDs are now included in the 18th Edition of the IET Wiring Regulations (BS 7671:2018).

BS 7671: 2018 states that examples of premises where AFDD’s are recommended to be installed include:

  • Premises with sleeping accommodation i.e. Residences, Hotels, Hostels etc.
  • Locations with a risk of fire due to the nature of processed or stored materials i.e. Barns, woodworking shops, Storage of combustible materials.
  • Locations with combustible construction materials i.e. Wooden Framed Buildings including Houses to the extent of even the wooden roof frame alone of a standard house.
  • Fire propagating structures. Locations with endangering of irreplaceable goods i.e. museums, premises housing critical business data.

Sources of Ignition:

The numbers are disturbing.

7,727 accidental fires were recorded in “electrical distribution” Apr16 – Mar17 in England alone. (source www.gov.uk/government/collections/fire-statistics)

Of these, 5,574 had wiring, cables and plugs recorded as the source of ignition. There were also 3,442 domestic appliance fires, with a total of 9,603 fires attributed to faulty appliances and leads.

The role of an AFDD:

AFDDs are purpose-designed to provide additional protection from fires caused by arc faults in 230V AC circuits.

AFDDs are electronic protection devices that analyse the waveform of an A.C. circuit to detect arc fault conditions. They are pre-programmed with data on ‘normal’ arcs (such as from manual or automatic switching and normal operation of electrical equipment e.g. a motor in a washing machine), which means that they can recognise potentially dangerous arc faults.

AFDDs detect arc faults by continuous monitoring of the circuit for a variety of conditions, including the duration of the arc, the irregularity and the waveform.

When they detect a fault, they disconnect the circuit from the supply to prevent the arc fault from leading to a fire.

What is an Arc Fault?

Arc faults are faults that occur either within or between conductors, for example, when cable insulation/insulation material of electrical equipment is damaged or a connection becomes loose.

These arcing conditions can cause overheating, leading to ignition of the cable insulation and surrounding materials.

Series arc faults are typically found in loose connections or frayed/damaged conductors.

They occur within the one conductor only (Live or Neutral), so there are no fault currents to earth or neutral.

Parallel arc faults are typically found with damaged or degraded insulation that allows current flow between conductors. The current flow in these conditions will always be less than that of the operating load current – which is why MCBs, RCDs and fuses are unable to detect these faults. The current flow and arcing temperatures can cause overheating and ignition of the cable insulation and surrounding materials.

For reference BS7671:2018 Regulations referring to the recommended use of AFDD’s are 131.1, 131.3.1, 131.3.2, 420.1, 421.1.1, 422.1.2, 421.1.7, 522.6.1, 522.6.2, 526.1, 532.1, 532.6, Appendix 6 schedule of inspections & schedule of test results. Not exhaustive, other requirements may also apply.

The 18th Edition Wiring Regulations and the use of SPD’s (Surge Protection Devices) for Protection of Transient Over voltages from Lighting Strikes and Supply Switching Origins.

Previously the requirements to provide surge protection devices or not was rather complex, requiring a classification code to be applied relating to the number of thunderstorm days at a location. This has all been removed and the 18th Edition now requires protection against transient over voltage (Lighting strike) to be provided where the consequences are:-

  • results in serious injury to, or loss of, human life, or; -results in interruption of public services/or damage to and cultural heritage, or; -results in interruption of commercial or industrial activity, or;
  • affects a large number of co-located individuals. SPDs are now required as part of BS 7671:2018 unless a risk assessment is performed and determines otherwise. Should a risk assessment NOT be performed then protection against transient overvoltage (an SPD) IS REQUIRED TO BE INSTALLED. These are installed either within the consumer unit or as a stand-alone unit adjacent to the consumer unit/within a set distance from the consumer unit

Single dwelling units however also require an assessment as to whether the total value of the installation and equipment therein justifies the inclusion of such protection, it should be noted that modern living in dwellings does encompass a large number of high value items such as Smart TV’s, Satellite receivers, Computer equipment, Wireless Broadband equipment, Boilers and controls, Games consoles, Washing machines, Fridge Freezers and other electrical appliances – not to mention the value of the entire electrical installation itself.

Some Home insurance may require an installation to adhere to the current edition of the wiring regulations thus an omission of an SPD could invalidate the insurance in the event of a lightning strike. It should be noted that not all premises would be required to have an SPD installed providing the risk assessment is carried out.