Inaugural Message

Since the enactment of the Electricity Ordinance in 1990, through public education and promulgation of the statutory safety requirements, we have been able to gradually enhance the public awareness on electrical safety. Nevertheless, we believe that we should continue to seek improvement in this area of increasing public concern. We feel that by further enhancing communication with the contractors and workers, we could raise the general level of expertise within the trade. The publication of this newsletter "Electricity News" is among one of our initiatives to achieve this goal.

This newsletter builds on the success of a seminar we co-organized late last year with two major trade organizations. Attended by some 800 registered electrical contractors and workers, the seminar was very successful in providing a forum to allow us to share our working experience in handling cases of non-compliance, discuss examples of negligence and the corresponding corrective measures. The response we received from staging this event was very encouraging.

This newsletter aims to continue the dialogue with the trade, and extend the communication coverage to a wider spectrum embracing all the registered electrical contractors and workers. By issuing this newsletter regularly, we hope to keep all practitioners in the trade informed of current regulatory requirements and technical guidelines. We also plan to share our experience in enforcing the regulations. This will help to highlight areas of interest for discussion and review.

Communication is by no means uni-directional, and EMSD would be pleased to receive feedback from the trade on this newsletter. Thus I very much hope that "Electricity News" will also become the means for trade practitioners to channel their views on electrical safety, including enforcement and other practical issues. I am confident that through enhanced communication, we will be able to join hands together to further raise the standard of electrical safety in Hong Kong.

Legislation Highlight

Electricity Ordinance and its subsidiary legislation came into effect in the early 1990s. A Performance Monitoring Point System for registered electrical contractors and workers was also introduced in 1994. EMSD's enforcement and publicity activities under this regulatory framework have brought about a marked improvement in the safety of electrical installations and the performance of registered electrical practitioners in Hong Kong.

We would like to take this opportunity to highlight for reference a few common contraventions made by the trade. In recent months from January 2001 to March 2002, EMSD investigated a number of complaints and accidents and took disciplinary action against 22 registered electrical contractors/workers who had committed offences when carrying out electrical work. They were either reprimanded or fined by the Director of Electrical and Mechanical Services under the Electricity Ordinance. The common contraventions were :

1. Failure to ensure that the fixed electrical installation was properly designed, constructed, installed and protected so as to prevent danger, in contravention of Regulation 4(2) of the Electricity (Wiring) Regulations;
2. Failure to ensure that safety precautions were taken to prevent danger arising from electrical wiring work done by him or under his supervision, in contravention of Regulation 4(7) of the Electricity (Wiring) Regulations;
3. Failure to ensure that Category 1 and 2 circuits were segregated from each other as far as is necessary to prevent danger and electrical interference, in contravention of Regulation 5(1) of the Electricity (Wiring) Regulations;
4. Failure to ensure that the results of the tests and inspections were satisfactory before the registered electrical contractor/worker issued the Periodic Test Certificate, in contravention of Regulation 21(4) of the Electricity (Wiring) Regulations; and
5. Failure to ensure that the extraneous conductive parts were effectively connected to the main earthing terminal of the fixed electrical installation, under the condition that the former and any adjacent earthed metal work of electrical equipment were simultaneously accessible, in contravention of Regulation 11(4) of the Electricity (Wiring) Regulations.

Electrical contractors and workers are reminded to carry out all electrical work in accordance with the Electricity (Wiring) Regulations and the associated Code of Practice. Failing to do so may lead to disciplinary action by EMSD.

For enquiries on registration and legislation, please contact our Customer Services Office (Tel.: 1823 Citizen's Easy Link) at G/F, EMSD Headquarters, 3 Kai Shing Street, Kowloon, Hong Kong.

Safety at Work

Two serious accidents occurred in recent months, both involving short-circuiting of live parts on low voltage electrical installations. In each case, the registered electrical workers (REWs) did switch off the mains and essential supplies at the consumer's switchboard in order to carry out periodic maintenance inspection. However, they did not isolate the electricity supply from the power company. As an unfortunate result of this careless act, in both cases the workers accidentally came into contact with the live parts of the installations, causing explosions in which the REWs received serious burn.

These accidents could have been prevented if the REWs had observed the relevant safety guidelines and precautions for the installations under maintenance. For details of the safety precautions, please refer to Code 4 of the Code of Practice for the Electricity (Wiring) Regulations. The following is a set of general safety practices that should be observed when periodic inspections are being carried out:

1. Check before you Act
   Check the scope of work and relevant circuit diagrams before starting your work.
2. Isolate and Lockout
   The circuit / equipment under maintenance should be isolated as far as practicable. The relevant isolator should be locked out. A suitable warning notice should be placed close to the isolator.
3. De-energize
   The circuit/equipment to be worked on should be checked by a reliable voltage detector to ensure that it is dead.
4. Others
   • Keep the work place clean and tidy.
   • Check the condition of your tools and instruments before work.
   • Keep hands away from any circuit or equipment that you are not working on.
   • Keep unauthorized people away from the work place.
   • Always follow procedures and check lists.

Please note that REWs should be responsible for the safety of themselves and their working team members.

Remember - Safety First!

Seminar for Registered Electrical Contractors and Workers

For the purpose of further improving the communication between EMSD and the electrical trade, a seminar was held on 23 November 2001 for registered electrical contractors/workers. Many questions were raised during the seminar. These questions together with EMSD's replies were subsequently uploaded to EMSD's homepage. Please select "About Us" and " Public Education" in the homepage for details.

New Initiatives on Registration Renewal

According to the Electricity (Registration) Regulations, registered electrical workers are required to renew their certificate of registration one to four months before the expiry date. Quite often, REWs missed the timely renewal of their certificates and as a result, the REWs are required to go through all the necessary steps in applying for a new certificate.

To assist REWs to renew the applications on time, EMSD has issued reminder letters together with application forms to REWs whose registrations are due to expire.

At the same time, procedures for the renewal of registration certificates by registered electrical workers have been simplified. Submission of employment letters or other supporting documents are no longer required. REWs are required to submit a duly completed new Form 8 together with the prescribed fee during application to renew their registration certificate.

New Application Forms

Our old four-page Form 8 for registration of electrical workers was for the purpose of application for both "new/change-of-grade" applications and renewal of registration. Certain information required by the old Form 8 is for "new/change-of-grade" application which is not required for renewal applications. As the majority of the applications for registration of electrical workers received by EMSD are renewal applications, we have revised the design of the form and as such a new Form 8 with only 2 pages was used for speeding up the renewal applications. Also, a new Form 8A was designed to retain the information required for "new/change-of-grade" applications. Hence, REWs need to submit the new Form 8 for renewal applications. However, for "new/change-of-grade" applications, workers are required to submit both the new Form 8 and Form 8A.

Apart from sending the application form to our Customer Services Office, submissions by mail or e-mail are also acceptable.

2nd Round Periodic Inspection and Testing for Electrical Installations

According to the Electricity (Wiring) Regulations, a low-voltage fixed electrical installation in a residential or commercial building with an approved loading exceeding 100A is required to be inspected, tested and certified at least once every five years.

If the installations were connected to the electricity supply before 1 June 1992 and completed a first periodic test before 1 June 1997, they are now due for a second round of testing. If you are aware of any electrical installation for which the periodic test certificate (WR2) will soon expire, please remind the relevant building owner/management company to carry out the second round testing as soon as possible.

Revision of the Code of Practice for the Electricity (Wiring) Regulations

Following the enactment of the Electricity (Wiring) Regulations in June 1992, EMSD published the Code of Practice for the Electricity (Wring) Regulations (CoP) to provide technical guidelines to workers and contractors in the electrical industry. Owing to changes in international electrical safety and testing standards and trade requirements for electrical installation and testing in Hong Kong, the CoP was revised in 1997.

In recent years, EMSD has received many suggestions from the trade on application of the CoP and the practical problem encountered by the trade arising from the rapid development of the electrical industry. In this regard, we are reviewing and revising this CoP and consultation was conducted at the beginning of this year. A working group has also been established to discuss the details of the revision. Areas covered in the review include bonding requirements, lightning protection requirements and harmonic current limits requirements. We are updating the reference list for international standards and adding an index page for quick reference. The new edition is expected to be released in next year.

Installation of Socket Outlet in Bathroom

EMSD has reviewed the requirements for the installation of socket outlets in bathrooms. The existing Code of Practice for the Electricity (Wiring) Regulations (1997 edition) has been amended. The amendments which have been effective since 1 April 2002, are summarised as follows:

In a room containing a bath or shower, provision for the connection of an electric shaver, toothbrush or similar light current appliance can be by means of a shaver supply unit of approved pattern complying with BSEN 60742 or such a unit incorporating in a luminaire. The earthing terminal of the shaver supply unit should be connected to the protective conductor of the final circuit from which the supply is derived.

In a room containing a bath or shower, the provision of socket outlets should comply with IEC 60364-7-701 (to be installed at location 0.6 m away from shower basin or bath tub) and the socket outlets should be protected by a residual current protective device (RCD) with a residual operating current not exceeding 30mA. When a circuit designer who is a Registered Electrical Worker for Grade A, B or C considers it appropriate for the situations under consideration, additional safety measures may be used. These measures include the use of a dedicated circuit or a dedicated circuit protected by an isolating transformer.

Verification of Extraneous Conductive Parts

In response to trade enquiries, we take this opportunity to explain one of the determination methods for extraneous conductive parts and their bonding requirements as specified in the Code of Practice for the Electricity (Wiring) Regulations (CoP).

The provision of equipotential bonding can effectively reduce the risk of electric shock arising from faulty electrical installations. To minimise bodily damage resulting from electric shock, it is necessary to minimise the electric current which flows through the person. The two principles to reduce the electric current are (i) to minimise the potential difference between the conductive objects simultaneously touched by the person, (ii) to insulate as far as practicable all other metal parts that could be touched by the person. The following paragraphs describe how equipotential bonding works to protect bodily damage in the event of an electric shock.

An extraneous conductive part means a conductive part liable to introduce a potential, generally an earth potential, that does not form part of an electrical installation. Typical examples are water mains and gas pipes. Equipotential bonding consists of main and supplementary equipotential bondings. It means the electrical connection linking various exposed conductive parts and extraneous conductive parts so as to achieve a substantially equal potential. Figure 1 illustrates the connection arrangement of circuit protective conductors (CPC) and bonding conductors to exposed and extraneous conductive parts. By proper installation of automatic disconnection devices, CPC and equipotential bonding, in case of an earth fault occurred in an installation, the voltage on any exposed/extraneous conductive parts occurring anywhere in the installation should be of such magnitude and duration as not to cause danger (please refer to Figure 2 and 3).

Designers and registered electrical workers may be uncertain whether conductive parts such as metallic bathroom accessories, metallic windows or metallic door handles are extraneous conductive parts. When difficulties are encountered, you may carry out a measurement as illustrated in Figures 4 and 5. In Figure 4, A is an exposed conductive part with a resistance Rcpc to main earthing terminal. The resistance to earth at the main earthing terminal is Re. B is suspected to be an extraneous conductive part and has a resistance Rx to earth. If Rx could always be maintained at not less than 21,000Ω, B could be considered as a non-extraneous conductive part.

In Figure 5, if a person is simultaneously touching A and B at the moment that there is an earth fault at equipment A, the fault current, If, will create a fault voltage Vf in this path. A voltage Vf will also be created in another path through B. Then, a current Ib will pass through the person (Rb). The associated equation is Vf = Ib (Rb + Rx). According to IEC 479, there is usually no harmful physiological effect if the body current is less than 10mA. Vf is taken as 220V which is the nominal supply voltage of a single-phase supply system. As stated in IEC 479, 95% of the population will have body resistance (hand-to-hand or hand-to-foot) exceeding 1,000Ω[ for a touch voltage of 220V. From the equation above, if Rx could always be maintained at not less than 21,000Ω[ under the worst conditions (including the environmental and external influences), there would be no harmful physiological effect for the person touching equipment A and B.

Based on the previous explanation, we could understand why a metallic door handle is usually not considered as an extraneous conductive part. If a proper installation method is used, the metallic accessories in bathroom could become non-extraneous conductive parts. Regarding the metallic windows, due to their exposure to external environment where rain and high humid conditions are prevalent, they are usually considered as extraneous conductive parts. The bonding connection method for extraneous conductive parts is specified in Code 11 of the CoP. You may also make reference to connection method as shown in figure 11(1) in the CoP. We hope that, after this discussion, you would be more familiar with the determination of extraneous conductive parts and their bonding connection requirements during your design and maintenance work.

Maintenance of Air-Conditioners

Air-conditioners would probably be your best companions in the summer. However, there has been some fire incidents that are suspected to be related to window type air-conditioners. For this reason, we often remind the public to arrange periodic inspection and maintenance on their air-conditioners by qualified persons. In carrying out electrical maintenance work for window type air-conditioners, registered electrical workers should follow the requirements specified in the Code of Practice for the Electricity (Wiring) Regulations. In addition, they should:

• carry out inspection and maintenance according to manufacturers' recommendations, in particular, the conditions of the control wirings and associated components, e.g. rotary switch, capacitor, etc.;
• arrange touching up or repainting of the structural frames if the air-conditioner is installed in corrosive environment, e.g. close to the sea; and
• inspect and carry out necessary maintenance work on the supporting framework to eliminate falling hazard.

Safety on Electrical Products

Be Cautious of Luminaire Installation

Nowadays, luminaires do not solely provide basic function of illumination but also serve as ornaments. Generally, most people focus on luminaires' aesthetic design and brightness when they are selecting luminaires. However, as a registered electrical worker, you are obliged to ensure that the luminaires install by you comply with the relevant safety requirements. Recently, the Consumer Council has conducted testing on some models of ceiling mounted luminaires. The test results indicated that some models could not fully comply with the relevant safety requirements. In addition, some of them may impose potential danger if not properly installed. As a registered electrical contractor/worker, you may deal with the installation of different types of luminaires from time to time. In view of public safety, you should observe the markings and installation instructions for the luminaires.

Luminaires that conform to the safety standard should bear proper markings of rated voltage, rated frequency, rated power, number and type of lamp bulbs, model number, mark of origin (manufacturer' name/trade mark) and symbol for suitability or non-suitability for direct mounting on combustible surfaces where applicable.

You should follow the installation instructions for the luminaires, such as installing away from combustible surface (wall paper, wooden false ceiling), allowing sufficient room for heat dissipation (particularly luminaires fitted with tungsten halogen lamps), ensuring effective earthing connection (such as adding star and spring washers at the earth terminal), and adopting proper anchorage to support its weight. After installation, you should advise your client the maximum power of replacement bulbs.

Typical markings for luminaires:

• Maximum rated power and the number of bulbs n x MAX ...W, n being the number of bulbs
• Symbol for suitability for direct mounting on combustible surface
• Symbol for non-suitability for direct mounting on combustible surface
• Symbol for suitability for mounting in/on combustible surface when thermally insulating material is used to separate the luminaire from the surface