Consumer Unit Guide to the 17th Edition Wiring Regulations

Posted on October 1, 2012 by 1,510 Comments

Consumer Unit guide to the 17th edition Wiring Regulations

Building Regulations

Part P of the building regulations relates to the electrical safety in dwellings. The approved document prescribes that consumer units should be located so that they are easily reachable where this is necessary to comply with Part M of the building Regulations.

Part M requires that reasonable provision be made for people to gain access to a building and use its facilities. The approved document prescribes that switches, socket outlets and “other equipment” needs to be at appropriate heights, these are defined as between 0.45m and 1.2m from finished floor level.

Other equipment may be taken to include the consumer unit, as it contains devices such as MCB’s and RCD’s that may need operation or resetting by the user of the dwelling. The consumer unit should therefore be accessible, with the devices mounted at a height no greater the 1.2m above the floor. In addition the consumer unit should not be in a location that would make it difficult to access such as an under stairs cupboard. Neither should it be placed in a position where is likely to be damaged by impact. Therefore depending on the layout of the dwelling a flush consumer unit may be considered.

Consumer Units should be easily reachable and be mounted with the switches at a height of between 0.45m & 1.2m above floor level

Requirements of 17th Edition Wiring Regulations BS 7671:2008

This section aims to explain some of the new Regulations contained within the 17th Edition Wiring Regulations, regarding the consumer unit and final circuits. Firstly however, to fully understand what is required, we need to consider some definitions from Part 2 of the Regulations.

  • Ordinary Person – Someone who is neither skilled or instructed
    e.g. General public / Home owner
  • Skilled Person – A person with technical knowledge or experience to enable him/her to avoid dangers which electricity may create
    e.g. Qualified Electrician
  • Instructed Person – A person who has been adequately advised or supervised to enable him/her to avoid dangers which electricity may create
    e.g. Facilities Manager

Typically commercial installations will be under the control of a Skilled or Instructed Person. However domestic and some commercial installations will not. This is particularly important, as certain Regulations only apply to installations not under the supervision of a Skilled or Instructed Person. A significant change is the introduction of Regulations requiring additional protection by RCDs. There are 3 points of consideration,

  1. Socket Outlets
  2. Cables buried in walls
  3. Locations containing a bath or shower

together with some other considerations, like the Division of Installation and about the Fire Detection and Fire Alarm Systems for buildings.

Certain Regulations only apply to installations not under the supervision of a Skilled or Instructed Person i.e. Ordinary persons.

The Regulations have introduced new requirements regarding socket outlets, particularly where used by ordinary persons e.g. Home owners.

Sockets Outlets

The definitions for persons are important to consider when we look at the requirements for protection of circuits supplying socket outlets.  Regulation 411.3.3 requires that an RCD of not exceeding 30mA be provided for:

  1. Socket outlets up to 20A that for general use by “ordinary persons”.
  2. Mobile equipment up to 32A that is for use outdoors.
    Exceptions to 411.3.3 are permitted where:
  3. Use of socket outlets is under the supervision of someone “skilled” or “instructed”.
  4. Specifically labelled or otherwise suitably identified socket outlets provided for a particular item of equipment.

This is a change from the 16th Edition that required only socket outlets ‘reasonably expected’ to supply equipment used outside the equipotential zone to have RCD protection e.g. used for an Electric lawn mower. Now under the requirements of the 17th edition it is likely that every socket outlet in a domestic installation will require RCD protection not exceeding 30mA. This may also apply to some commercial installations, like small offices or shops etc where there is no control on the use of those socket outlets. Consideration should also be given to areas where free access to socket outlets is available to the general public e.g. airport lounges.

Socket outlets for general use in a domestic installation require RCD protection not exceeding 30mA

Significant changes affect installations where cables are buried in the wall. This is the normal practice in dwellings.

Cables buried in the wall

Here we need to consider Section 522, Selection and erection of wiring systems in relation to external influences. The particular requirements of this section apply to cables which are concealed in a wall or partition at a depth of less than 50mm, or where metal partitions are used. The definitions for persons are once again important for this section. There are 5 options of installing cables in walls. The cables shall:

  1. Incorporate an earthed metal covering which is suitable as a protective conductor. Eg SWA cable.
  2. Be enclosed in earthed metal conduit, such that is suitable as a protective conductor.
  3. Be enclosed in earthed metal trunking, such that is suitable as a protective conductor.
  4. Be protected against damage from penetration by nails or screws.
  5. Be installed in a safe zone.

This is much the same as the 16th Edition requirements and the usual option is to install cables in a dedicated safe zone. However, where an installation is not under the supervision of someone skilled or instructed, regulation 522.6.7 applies. In this regulation where (5) only from above is used then the cable must have additional protection by the use of a RCD not exceeding 30mA. This would apply where thermoplastic (PVC) wiring systems are used, this is typical in most domestic installations and some commercial installations.

Where buried cables are not mechanically protected additional protection by an RCD not exceeding 30mA must be provided

Although additional regulations relating to bathrooms etc are not new, there are some important changes to consider. 

Section 701, Locations containing a bath or shower

Regulation 701.411.3.3 requires that all circuits within this location shall be additionally protected by an RCD not exceeding 30mA. This would mean 230V lighting, the 230V supply to the source for SELV, a shower circuit and bathroom heater for example will all need RCD protection. A standard 13A socket outlet is now permitted in this location provided however the socket outlet is more than 3m from the boundary of zone 1.

The 16th Edition required local supplementary bonding be provided connecting together all exposed and extraneous conductive parts in the zones. This is no longer required in this location provided the following conditions are met:

  • All final circuits of the location comply with the automatic disconnection requirements according to regulation 411.3.2.
  • All circuits are RCD protected in accordance with 701.411.3.3.
  • All extraneous-conductive parts of the location are effectively connected to the protective equipotential bonding according to regulation 411.3.1.2 (Previously termed main equipotential bonding).

All circuits in locations containing a bath or shower shall be protected by an RCD not exceeding 30mA

Other Considerations

There are additional Regulations and Codes of Practice that need to be considered during the design of an installation. These will affect the choice of consumer unit.

Division of Installation

Section 314 calls for the installation to be so divided to:

  1. Avoid hazards and minimize inconvenience in the event of a fault
  2. Reduce the possibility of unwanted tripping of the RCD due to excessive protective conductor currents.

To comply with these requirements the circuits of an installation should not be connected to a single RCD, as this could lead to loss of supply to the entire installation in the event of a fault on one circuit, clearly inconvenient for the user of the building.

All circuits of an installation should not be connected to a single RCD

The Wiring Rules & Building regulations are not the only documents that need to be consulted, another important document relates to smoke alarms.

BS 5839-6:2004 Fire detection and Fire alarm systems for buildings

This Code of Practice has particular requirements for dwellings. This document makes reference to the power supply to such systems and mentions RCD’s. The circuit supplying these systems should preferably not be protected by an RCD. This however is going to be difficult to achieve if the circuit supplying these systems is buried in the walls and standard domestic wiring systems are used. Indeed the supply cables would need to be specially protected in earthed metal conduit etc. for RCD protection not to be used.

Options for circuits supplying fire or smoke alarms in dwellings protected by an RCD include:

  1. The RCD serves only that circuit. For example with the use of an RCBO
  2. The RCD operates independently of any RCD feeding socket outlets or portable equipment

So consideration of these points is necessary during the design stage and particular care is needed to select the appropriate consumer unit and wiring system to ensure compliance. BS 5839-6 should always be studied to ensure that all relevant recommendations are complied with.

Where RCD protection is needed for smoke detector circuits one option is to supply that circuit only


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Commercial Electrical Installation and Maintenance

Posted on June 12, 2012 by 1,062 Comments

Commercial Electrical Installation and Maintenance

Commercial electrical installation and maintenance. Robert Swain Electrical Services Ltd, ,  has an excellent track record in working  on commercial premises. We have expertise in a range of electrical services for offices, from retro-fit low energy lighting to installing back-up generators.

We specialise in office moves, making your business relocation run smoothly. Our commercial services include:

  • Installations, Repairs & Maintenance
  • Rewiring & Upgrades
  • Fire / Emergency Lighting
  • Re-lamping/Lighting Maintenance
  • Electrical Installation Condition Reports
  • Shop / Office fitting & conversions
  • Data & computer cabling

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Emergency Lighting

Posted on June 12, 2012 by 835 Comments

Emergency Lighting

Robert Swain Electrical Services Ltd, have a great many years experience in emergency lighting systems, the servicing of and the maintenance of such installations, as well as the design of bespoke emergency lighting installations.

Why Emergency Lighting is required

Emergency lighting is required by law in all commercial and industrial premises, and also in Public Buildings.In the event of a power outage, emergency lighting is absolutely essential to guarantee the safety of all of your employees.

Emergency exits will be highlighted by our automatic emergency lighting signs and lamps, which will assist people to safely escape in emergency circumstances.

Emergency Lighting Installations by Robert Swain Electrical Services Ltd

It is absolutely crucial for any industrial or commercial premises to have an emergency lighting system installed, and to ensure that their emergency lighting installation is regularly serviced and tested, to make sure that it is in proper working order in the event of a power failure or fire.Included in our emergency lighting design is a site survey, after which we will advise you on which is the best emergency lighting system for your business premises.

We will make sure that any emergency lighting system we install will comply with all the very latest safety regulations. Not only that, but we will also regularly check and test your emergency lighting installation and issue you with a report which will guarantee that your new emergency lighting system fully complies with all of the latest safety regulations and Fire Safety Certification.

EM Lighting for Business - Local Commercial Electrician

Emergency Lights


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Posted on September 4, 2011 by 1,200 Comments


Why do I need to carry it out?
The Electricity at Work Regulations 1989 places a “duty of care” on employers and landlords to maintain electrical systems to prevent danger where otherwise it may exist. The only way of ensuring your duties are performed and adequate records are kept is by carrying out a Electrical Installation Condition Report in accordance with BS 7671 (The IEE Wiring Regulations).
By following this practice, you can be sure that your obligations have been met under the Health and Safety at Work Act so far as electrical safety is concerned and more importantly that your staff, visitors, patients, buildings and possessions are safe and that your insurance company will pay out in the event of a claim arising from an electrical fault or fire (check your small print!).

What does it involve?
The Electrical Installation Condition Report requires a series of visual inspections and electronic tests to be performed to establish the safety and suitability of your electrical system. If performed correctly, you can expect that each electrical circuit within your workplace will have to be de-energised for a period of 15 minutes whilst the Engineer injects test voltages and currents into the cables and protective devices to ensure their integrity and carries out a thorough visual inspection of the Installation. This type of work will require the main supply to be isolated and with careful planning can be done with little disruption to your business. Alternatively, this work can be carried out whilst your workplace is empty, such as nights or weekends.

Who should do the work?
It is vital that this type of work is carried out by qualified and experienced Approved Test Engineers. Such Engineers are generally fully qualified electricians who have been trained and qualified to City & Guilds 2391 in Electrical Inspection work specifically. All Robert Swain Electrical Services engineers meet these requirements.

Will it impact on my workplace?
There will be some impact such as short periods of downtime on circuits; however, with careful planning and strong liaison between us, this can be conducted at a time that best suits your business. Be wary of contractors that tell you this work can be carried out without isolating circuits – it is impossible.

What will I receive?
Upon completion of the Electrical Installation Condition Report, you will receive a bound BS7671 report and CD that details the following:
• Installation details and characteristics
• Circuit information and test results
• Schedule of items tested and inspected
• A list of defects or deviations from BS 7671 (these may require attention)
If you are not a technical person, then we will be pleased to talk through your report with you and advise you of any further action required.
Any necessary remedial works can be carried out by ourselves or a 3rd party contractor of your choice. On completion, a ‘satisfactory’ assessment can be issued.

How much will it cost?
There are many factors that can affect the cost of Electrical Inspection work such as location, type of installation, size of building(s), access and availability of previous records. As a rule of thumb, we will attend site (free of charge) prior to quoting to survey the building(s) in order to establish all of the necessary details, you should be wary of accepting a quotation unless a full survey has been conducted or you are sure you have provided enough information.

What could happen if I don’t do it?
Reasons such as cost, inconvenience, or lack of knowledge will not be accepted as a defence in the event that an accident or fire occurs. Aside
from the threat of prosecution in the event of injury or death, many insurance companies will not pay out if documented evidence of maintenance and inspections is not available.

Why use Robert Swain Electrical Services?
• We only ever use fully qualified, experienced 2391 inspectors.
• We do not insist on carrying out remedial works.
• We provide hard and digital copies of reports.
• We can provide testimonials and references from satisfied clients across all sectors and regions.
• We can carry out Portable Appliance Testing (additional package).
• We can carry out Thermal Imaging Testing which is often an insurance company requirement (additional package).
• We are an NICEIC Domestic Installer assessed company.

BS7671 intervals between Electrical Installation Condition Report
Type of installation Maximum period between inspections

  • Domestic premises 10 years or change of occupier
  • Commercial premises 5 years or change of occupier
  • Educational establishments 5 years
  • Hospitals 5 years
  • Industrial premises 3 years
  • Cinemas 1 year
  • Churches 5 years
  • Leisure complexes 1 year
  • Places of public entertainment 1 year
  • Theatres, etc. 1 year
  • Agricultural and horticultural 3 years
  • Caravans 3 years
  • Caravan sites 1 year
  • Emergency lighting 3 years
  • Fire alarm systems 1 year
  • Launderettes 1 year
  • Petrol filling stations 1 year
  • Public Houses 5 years
  • Marinas 1 Year
  • Highway power supplies 6 years

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Electrical Installation Condition Report

Posted on April 13, 2011 by 1,082 Comments

Information on The Electrical Installation Condition Report

All electrical installations deteriorate due to a number of factors, i.e. damage, wear and tear, corrosion,  excessive electrical loading, ageing and environmental influences. Legislation requires that electrical installations are maintained in a safe condition and therefore must be periodically inspected and tested.  Also, licensing authorities, public bodies, insurance companies, mortgage lenders and others may  require The Electrical Installation Condition Report of electrical installations additionally, Periodic Inspection and Testing should be considered to assess compliance with BS 7671 (IEE Wiring Regulations), on a change of occupancy of the premises, on a change of use of the premises, after alterations or additions to the original installation, because of significant change in the electrical loading of the installation or where there is reason to believe that damage may have been caused to the installation.

About The Electrical Installation Condition Report

A series of well defined visual checks are carried out on the electrical installation followed by several different electrical measurements including continuity of circuit protective conductors, main and supplementary earth bonding, Continuity of ring final circuit conductors, Insulation resistance, Polarity, Earth-fault Loop Impedance, RCD tests including trip time in milliseconds, correct operation of switches and isolators, Prospective Fault Current.

In general the inspection should reveal:

1. Any aspects of the installation that may impair safety of persons or livestock against the effect of electric shock and burns

2. That there are no defects that could give rise to heat and fire and hence damage property

3. That the installation is not damaged or deteriorated so as to impair safety

4. That defects or non-compliance with the Regulations that may give rise to danger are identified.

Standard domestic Electrical Installation Condition Reports normally require up to 4 hours on-site. The client will be provided with test documentation and certification within 48 hours to allow the test data to be entered into our database.

If you would like to book an Electrical Installation Condition Report, Domestic or Commercial, contact Robert Swain Electrical Services Ltd using the Website Contact Page or Tel: 01425 279885


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