Introduction to Project Electrical Design

Project electrical design is the analysis of the client's brief and the formulation of a design that meets that brief.

It is important to note that these articles do not take into account the regulations and rules for the design of electrical installations for licensed premises, mines, ships, aircraft, railway rolling stock, or vehicles. Although the principles of the design detailed in this article may be applied to the design of those installations, with due regard being given to any applicable regulations and rules for the particular type of installation.

Every design has to start with the consideration of the requirements. These requirements are given by the client in the form of a brief, it is important to understand the brief, if you have any doubts ask. Where the brief covers the control of a process learn that process.

The client has a very important part to play at this stage of a project, as their input will bring to the fore the most suitable design that fits the brief and satisfies the client. It will also be necessary to determine with the client the type of electricity supply that is most appropriate for the project and whether standby generation or UPSs will be required together with the level of supply security of the electrical system.

It is at this stage also that the project costing and project programming can begin.

Be absolutely honest with the client as to the cost and time scale required for the delivery of the project; a successful project is one that is brought in to budget and on time. That cost and plan should be the one developed at this stage of the project. It should be a matter of professional pride that the project has been brought in to the original budgeted cost and original project program.

There are certain key requirements when developing a design. It must meet the client’s brief, enable the client to safely operate and maintain the electrical equipment that is to be supplied and installed as part of the project, that the installed equipment includes no environmentally damaging materials and can be recycled or safely disposed of at the end of life of the installation.

The project must be designed to comply with any legal requirements, in England these are enshrined in the Electricity at Work Regulations 1989 [Statutory Instrument (SI) no. 1989-635]. Electrical engineers, designers, electricians and others usually quote BS 7671 Requirements for Electrical Installations - IET Wiring Regulations as their bible, they should not.
If the IET Wiring Regulations (originally the IEE Wiring Regulations) are equated to the bible then the Electricity at Work Regulations equate to the ten commandments.

In the design of an electrical system the key clauses of the Electricity at Work Regulations that relate are:-

Regulation 3 - Persons on whom duties are imposed by these regulations

(1)Except where otherwise expressly provided in these regulations, it shall be the duty of every -
(a) employer and self employed person to comply with the provisions of these Regulations in so far as they relate to matters which are within his control; and
(b)
(i) manager, in relation to a mine within the meaning of section 180 of the Quarries Act 1954, and
(ii) operator, in relation to a quarry within the meaning of Regulation 3 of the Quarries Regulation 1999,
to ensure that all requirements or prohibitions imposed by or under these regulations are complied with in so far as they relate to the mine of which he is manager or quarry of which he is the operator and to matters which are within his control.
(2) It shall be the duty of every employee while at work -
(a) to co-operate with his employer so far as is necessary to enable any duty placed on that employer by the provisions of these Regulations to be complied with; and
(b) to comply with the provisions of these Regulations in so far as they relate to matters which are within his control.

Regulation 4 - systems, work activities and protective equipment

(1) All systems shall at all times be of such construction as to prevent, so far as is reasonably practicable, danger.
(2) As may be necessary to prevent danger, all systems shall be maintained so as to prevent, so far as is reasonably practicable, such danger.
(3) Every work activity, including operation, use and maintenance of a system and work near a system, shall be carried out in such a manner as not to give rise, so far as is reasonably practicable, to danger.
(4) Any equipment provided under these Regulations for the purpose of protecting persons at work on or near electrical equipment shall be suitable for the use for which it is provided, be maintained in a condition suitable for that use, and be properly used.

Regulation 5 - Strength and capability of electrical equipment
No electrical equipment shall be put into use where its strength and capability may be exceeded in such a way as may give rise to danger

Regulation 6 - Adverse or hazardous environments
Electrical equipment which may reasonably foreseeably be exposed to–

(a)mechanical damage;
(b)the effects of the weather, natural hazards, temperature or pressure;
(c) the effects of wet, dirty, dusty or corrosive conditions; or
(d) any flammable or explosive substance, including dusts, vapours or gases,

shall be of such construction or as necessary protected as to prevent, so far as is reasonably practicable, danger arising from such exposure.

Regulation 7 - Insulation, protection and placing of conductors
All conductors in a system which may give rise to danger shall either–

(a) be suitably covered with insulating material and as necessary protected so as to prevent, so far as is reasonably practicable, danger; or
(b) have such precautions taken in respect of them (including, where appropriate, their being suitably placed) as will prevent, so far as is reasonably practicable, danger.

Regulation 8 - Earthing or other suitable precautions
Precautions shall be taken, either by earthing or by other suitable means, to prevent danger arising when any conductor (other than a circuit conductor) which may reasonably foreseeably become charged as a result of either the use of a system, or a fault in a system, becomes so charged; and, for the purposes of ensuring compliance with this regulation, a conductor shall be regarded as earthed when it is connected to the general mass of earth by conductors of sufficient strength and current-carrying capability to discharge electrical energy to earth.

Regulation 9 - Integrity of referenced conductors.
If a circuit conductor is connected to earth or to any other reference point, nothing which might reasonably be expected to give rise to danger by breaking the electrical continuity or introducing high impedance shall be placed in that conductor unless suitable precautions are taken to prevent that danger.

Regulation 10 - Connections
Where necessary to prevent danger, every joint and connection in a system shall be mechanically and electrically suitable for use.

Regulation 11 - Means for protecting from excess of current
Efficient means, suitably located, shall be provided for protecting from excess of current every part of a system as may be necessary to prevent danger.

Regulation 12 - Means for cutting off the supply and for isolation

(1) Subject to paragraph (3), where necessary to prevent danger, suitable means (including, where appropriate, methods of identifying circuits) shall be available for–
(a) cutting off the supply of electrical energy to any electrical equipment; and
(b) the isolation of any electrical equipment.
(2) In paragraph (1), “isolation” means the disconnection and separation of the electrical equipment from every source of electrical energy in such a way that this disconnection and separation is secure.
(3) Paragraph (1) shall not apply to electrical equipment which is itself a source of electrical energy but, in such a case as is necessary, precautions shall be taken to prevent, so far as is reasonably practicable, danger.

Regulation 13 - Precautions for work on equipment made dead
Adequate precautions shall be taken to prevent electrical equipment, which has been made dead in order to prevent danger while work is carried out on or near that equipment, from becoming electrically charged during that work if danger may thereby arise.

Regulation 14 - Work on or near live conductors
No person shall be engaged in any work activity on or so near any live conductor (other than one suitably covered with insulating material so as to prevent danger) that danger may arise unless–

(a) it is unreasonable in all the circumstances for it to be dead; and
(b) it is reasonable in all the circumstances for him to be at work on or near it while it is live; and
(c) suitable precautions (including where necessary the provision of suitable protective equipment) are taken to prevent injury.

Regulation 15 - Working space, access and lighting
For the purposes of enabling injury to be prevented, adequate working space, adequate means of access, and adequate lighting shall be provided at all electrical equipment on which or near which work is being done in circumstances which may give rise to danger.

Regulation 16 - Persons to be competent to prevent danger and injury
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 possesses such knowledge or experience, or is under such degree of supervision as may be appropriate having regard to the nature of the work.

The Electricity at Work Regulations can be downloaded from the UK government’s website at the following address:-
http://www.legislation.gov.uk/uksi/1989/635/contents/made
the guidance notes to the regulations can be downloaded from the Health and Safety Executive website at the following address:-
http://www.hse.gov.uk/pubns/books/hsr25.htm

When an electricity supply is requested from the PES they are obliged by statute [The Electricity Safety, Quality and Continuity Regulations 2002 (SI No. 2002-2665)] to provide the characteristics of that supply.

The relevant clauses of the Electricity Safety, Quality and Continuity Regulations are:-

Declaration of phases, frequency and voltage at supply terminals

(27.)
(1) Before commencing a supply to a consumer’s installation, or when the existing supply characteristics have been modified, the supplier shall ascertain from the distributor and then declare to the consumer
(a)the number of phases;
(b)the frequency;
(c)and the voltage,
at which it is proposed to supply electricity and the extent of the permitted variations thereto.
(2) Unless otherwise agreed in writing between the distributor, the supplier and the consumer (and if necessary between the distributor and any other distributor likely to be affected) the frequency declared pursuant to paragraph (1) shall be 50hertz and the voltage declared in respect of a low voltage supply shall be 230 volts between the phase and neutral conductors at the supply terminals.
(3) For the purposes of this regulation, unless otherwise agreed in writing by those persons specified in paragraph (2), the permitted variations are -
(a)a variation not exceeding 1 per cent above or below the declared frequency;
(b)in the case of a low voltage supply, a variation not exceeding 10 per cent above or 6 per cent below the declared voltage at the declared frequency;
(c)in the case of a high voltage supply operating at a voltage below 132,000 volts, a variation not exceeding 6 per cent above or below the declared voltage at the declared frequency;
(d)and in the case of a high voltage supply operating at a voltage of 132,000 volts or above, a variation not exceeding 10 per cent above or below the declared voltage
(4) The Secretary of State may, following an application by any distributor affected by a declaration made pursuant to paragraph (1), authorise the variation of any of the values or permitted variations contained in a declaration provided that the applicant has previously given notice of his application to such persons and in such terms as the Secretary of State may require.
(5) Where the Secretary of State has authorised a variation under paragraph (4) the distributor shall forthwith serve notice of any such variation on every supplier, other distributor referred to in paragraph (2), and consumer to whom it may apply.
(6) Every distributor shall ensure that, save in exceptional circumstances, the characteristics of the supplies to consumer’s installations connected to his network comply with the declarations made under paragraph (1).
(7) The number and rotation of phases in any supply shall not be varied by the distributor except with the agreement of the consumer or, in the absence of such agreement of the consumer or, in the absence of such agreement, the consent of the Secretary of State who may impose such conditions, if any, as she thinks appropriate.

Information to be supplied on request

(28.) A distributor shall provide, in respect of any existing or proposed consumer’s installation which is connected or is to be connected to his network, to any person who can show reasonable cause for requiring the information, a written statement of-
(a) the maximum prospective short circuit current at the supply terminals;
(b) for low voltage connections, the maximum earth loop impedance of the earth fault path outside the installation;
(c) the type and rating of the distributor’s protective device or devices nearest to the supply terminals;
(d) the type of earthing system applicable to the connection; and
(e) the information specified in regulation 27 (1),
which apply, or will apply, to that installation.

The Electricity Safety, Quality and Continuity Regulations 2002 (SI No. 2002-2665) can be downloaded from the UK government’s website at the following address:-
http://www.legislation.gov.uk/uksi/2002/2665/contents/made
the guidance notes to the regulations can be downloaded from the UK government’s website at the following address:-
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/82785/Guidance2006.pdf

Another set of regulations that apply in England are the CDM regulations [The Construction (Design and Management) Regulations 2007 – SI no. 2007-320] these require risk assessments to be carried out for all aspects of the design, and for method statements for the installation. This is to cover up the poor standard of training for the modern apprentice electrician and therefore the modern electrician, and to assist the governments' health and safety inspectors who come out of university and have absolutely no practical knowledge or experience at all, this of course assumes that those mentioned in this paragraph can read.

The Construction (Design and Management) Regulations 2007 – SI no. 2007-320 can be downloaded from the UK government’s website at the following address:-
http://www.legislation.gov.uk/uksi/2007/320/contents/made
The guidance notes to the regulations can be downloaded from the Health and Safety Executive website at the following address:-
http://www.hse.gov.uk/construction/cdm.htm

There is one other key factor in the design process that must be given consideration, you must remember that when you design you will, ultimately, be controlled by accountants who have the visionary attributes of bats, their motto is always look at the cost today it does not matter how much we spend in the future to do what we should be doing now. The project build budget is exactly that, the money for building the project, the maintenance budget is considered to be unrelated to the build budget therefore the project finance team will take no account of the future costs of maintaining what is installed. This is a direct result of the stupid way that accountants work, it also happens to be the way Parliament finances the public projects so the politicians lead and accountants follow, no wonder the country is in a mess.

A note on why honesty is the best policy.
In the Ministry of Public Buildings and Works (MPBW) the project teams connived with the Ministry of Defence (MOD) to under price project costs so that they could get the finance voted for by Parliament. The MPBW would then buy the capital plant and then go back to Parliament for more money to incorporate the capital plant into the project. Knowing full well that if Parliament did not give the money the resulting pile of unused capital plant rotting away would cause greater embarrassment to Parliament than the approval of the additional funding to complete the project. On one particular project the permanent secretary of the MPBW was called before the public accounts committee which is a parliamentary committee to explain the cost overrun. Prior to attendance at the hearing, he went to the site to see for himself the project. At the site the MPBW project team and contractors held a meeting with the permanent secretary so they could explain the technical and financial position and give their excuses for the cost increases, as the meeting started the permanent secretary stated that he did not wish to be confused with the facts, and that he had no wish to discuss the project in any detail.

His lack of interest was explained by his reasoning that what he did not know about he could not be accused of lying in regard of it.

Was Sir Humphrey modelled on him??? (yes minister and yes prime minister)

A word of warning regarding deceit by the project team, the connivance of the MPBW with the MOD led to the complete demise of the PSA which was the successor to the MPBW even Parliament gets to the stage of enough is enough and the project department was the one for the chop, that is the PSA, not the MOD who were accessories before, during and after the fact. The MOD is still notorious for the cost overruns of its projects twenty years after the PSA was dumped by the Conservative government of the day. A lesson that has not been forgotten and will never be forgiven.