Notes from Deputy Director

Mr. HO Kwong-wai, JP
Deputy Director of EMSD

It gives me great pleasure to write the opening of the second issue of the Electricity News.

The purpose of the Electricity News is to enhance our communication with the registered electrical contractors and workers, and to update them with the latest development in technical and regulatory matters in the electrical trade. Since the first issue was published, we have continuously received encouraging response from various parties. This presses upon us to work even harder to produce this Electricity News with more informative contents.

As with the previous issue, you will find two feature articles, four pieces of news update, and some miscellaneous sidelights that may be of interest to you. In view of the recent accident about the burst of a shower type electric water heater, we have particularly written a feature article, delineating the internal structure, explaining why an on/off control valve should not be installed at the water outlet, and highlighting the precautions that should be taken into account when installing a shower type electric water heater. We hope that the article will be useful to you. In another feature article, we have, in response to the requests from members of the trade, provided answers to some frequently asked questions concerning the application for becoming a registered electrical worker.

The first issue of the Electricity News has already aroused useful feedback from you. I hope that you will continue to support this Electricity News by giving your valuable response. In doing so, we can establish a perpetual link to sustain our common goal in the continuous enhancement of electrical safety in Hong Kong.

Tips on the Installation of Electric Water Heaters

The typical household shower type electric water heaters (also known as low-pressure water storage or open-outlet type electric water heaters) in Hong Kong are rated at 220 V, single phase, with storage capacity ranging from about 10 litres to 20 litres and power consumption of 2 kW, 3 kW and 4 kW. The most common model has a storage capacity of 15 litres and a power consumption of 3 kW.

You may have learnt from our publicity materials that one should not add any on/off control valve at the outlet of a shower type electric water heater. Recently, we received a lot of enquiries about the installation and use of shower type electric water heaters. Many people asked why it was improper to add an on/off control valve at the outlet of a shower type electric water heater.

To understand the reason, let us start from the internal structure of a shower type electric water heater. Apart from being equipped with cold and hot water pipes, a mixing faucet, a shower head and thermostat controlled heating element, a typical shower type electric water heater is also provided with a thermal cutout. The red knob shown in Figure 1 is in fact the inlet control of the water heater. When the red knob is turned on, cold water will enter the water heater from the bottom. The cold water displaces the water heated up by the heating element through the outlet pipe at the top of the water heater and the shower head. The blue knob shown in the figure is used, via adding an appropriate amount of cold water, to adjust the water temperature as desired by the user. In the standby condition (i.e. when the red and blue knobs are closed), the water in the storage tank undergoes thermal expansion. As there is no control valve between the mixing faucet and shower head, the pressure inside the storage tank will be released through the shower head.

However, if an on/off control valve is added at the outlet of the electric water heater, then when the valve is closed, the vented passage in the storage tank is blocked. Under this situation, if there is a fault in the thermostat, the heating element will overheat the water and the pressure built up inside the storage tank cannot be released.

If the thermal cutout fails to disconnect the power supply, the storage tank will not be able to withstand the increasing pressure and this will result in a burst. Thus, to ensure safety, one should not add any on/off control valve at the outlet of a shower type electric water heater.

The associated water pipes and the fixed electrical installation of the shower type electric water heater should be respectively installed by a licensed plumber and a registered electrical worker (REW). When installing the fixed electrical installation, apart from earthing the water heater effectively, the REW should also check whether the electric water heater operates properly (including the function of the thermostat) and remind the user not to switch to any non-genuine open type mixing faucet and shower accessories or add any on/off control valve at the outlet of the water heater. When carrying out maintenance work on a shower type electric water heater, the REW should follow the manufacturer's instruction. He should in particular check whether the fixed electrical installation and pipes are properly installed and whether the thermostat operates normally. If necessary, he should consult the relevant agent or manufacturer. In case the REW finds that the outlet pipe is not properly installed, he should remind the user to appoint a licensed plumber to fix the problem immediately, thereby safeguarding the user against the occurrence of an accident.

Do not connect the outlet pipe of a shower type electric water heater to a wash basin or bath tub, lest the outlet pipe will be blocked, leading to excessive pressure being built up inside the water heater, and resulting in an accident.

In the preliminary investigation of a shower type electric water heater bursting accident, it was revealed that the user did not switched off the power supply after using the electric water heater. The water heater was found not properly installed as an on/off control valve was added at the water outlet. Thus, when the water was heated, the increased pressure inside the water heater could not be released through the outlet. Moreover, the thermostat of the water heater might have failed to function . All these factors contributed to the result of bursting.

Figure 2 shows the remains of the electric water heater after the accident. As you can see the metal enclosure, stainless steel storage tank and the heating element were all twisted out of their original shape. You may imagine how severe the burst was. To prevent the recurrence of such accidents, all REWs should pay attention to the above issues while installing or repairing shower type electric water heaters.

Matters Relating to the Registration of Electrical Workers

Recently, EMSD received a number of enquiries about the registration of electrical workers. These enquiries can be divided into the following 3 categories:

1. Examinations or trade tests recognized by EMSD;
2. Recognized qualifications for changing the grade of registration; and
3. Renewal application in respect of an expired registration.

Our responses below serve as a useful reference for all electrical workers having similar queries.

As we all know, to become a registered electrical worker (REW) of a certain grade, an applicant has to fulfil, as stipulated in the Electricity (Registration) Regulations, the qualifications and work experience requirements for that particular grade. These requirements can be found in the appendix to the application form (Form 8) and the leaflet entitled "How to Apply for Registration as an Electrical Worker".

Many electrical workers enquired about the meaning of "the examinations or trade tests recognized by EMSD". To answer this question, we have to reckon that these examinations/test are held for those who would like to be registered as Grade A, B or C electrical workers but do not possess the recognized academic qualifications. Details of the examinations/test are tabulated below:

For those REWs who are interested in obtaining a higher grade of registration but do not possess the qualifications required, they can enrol in the recognized academic courses. After completing the courses, they will fulfil the qualification requirements as stipulated in the Electricity (Registration) Regulations e.g. Craft Certificate in Electrical Engineering (for Grade A electrical work) and Diploma in Electrical Engineering (for Grade B electrical work), etc. Alternatively, they may fulfil the qualification requirements by passing the examinations/test as stated in the above table. However, to become a REW of a certain grade, an applicant has to possess adequate electrical work experience apart from obtaining the suitable qualifications. For those who are not registered as Grade A electrical workers but have passed the "Examination for Registration as a Grade B Electrical Worker", they are still required to possess the qualification for holding a Grade A registration certificate for at least 5 years and have at least 5 years' work experience in fixed electrical installation having a capacity exceeding 400A in order to be qualified for Grade B registration.

Besides, in recent years, a number of Grade A electrical workers forgot to renew their registration and hence their subsequent applications for renewal were rejected. Under regulation 13 of the Electricity (Registration) Regulations, REWs are required to renew their registration 1 to 4 months before the expiry date. Otherwise, they are required to submit new applications. In the early implementation stage of the Electricity (Registration) Regulations, those who applied for registration as Grade A electrical workers could obtain their registration if they had been employed as electrical workers for at least 6 years under the concessionary requirement in regulation 4(2)(c). However, this regulation has no longer been valid since the end of 1996, and if electrical workers registered via this route do not renew their registration on time, they are required to fulfil the qualification requirements and work experience specified in the current regulations when they apply for registration again. Thus if applicants do not have the qualifications required for Grade A electrical workers, they are required to pass the "Trade Test for Electricians" held by VTC (tel. 2836 1875) or to complete a 20-evening "Part-time Electrician/Electrical Fitter Upgrading (Safety)" course (EL-312) organized by VTC (tel. 2420 4253 ext. 359). After passing the examination of either course, they can re-apply for registration as Grade A electrical workers. In order to avoid the applications to be rejected, we would like to remind REWs to renew their registration on time.

In view of the past experiences that one has to wait for a long period of time before being able to enrol in the 20-evening part-time course or to take the Trade Test for Electricians, EMSD has discussed the matter with VTC. After the discussion, VTC launched a series of new measures in mid 2002 to reduce the waiting time. For the 20-evening part-time course, VTC has specially offered some mixed-mode classes organized on Sundays. As for the Trade Test for Electricians, VTC has offered two standby quotas for replacement of those who are absent from the test. Electrical workers can apply for the normal quotas as well as the standby quotas for the test. However, those who apply for the standby quotas can only take the test when there are absentees.

Should you have further enquiries or comments on the registration, please contact us (tel: 2882 8011, fax: 2895 4929 or e-mail: ci.eld@emsd.gov.hk). We will try every effort to answer your questions.

Note:

Under the Electricity (Registration) Regulations, all electrical work should be carried out by REWs of the appropriate grade. REWs should ensure that their work on fixed electrical installations complies with the requirements of the Electricity (Wiring) Regulations and the relevant Code of Practice. REWs should also bring their valid registration certificate with them for inspection by the relevant parties and their clients when carrying out electrical work.

Notes on Registration as Electrical Contractors

Under section 34(1) of the Electricity Ordinance, no person shall do business as an electrical contractor or contract to carry out electrical work unless he/she is a registered electrical contractor (REC). An electrical contractor who intends to apply for registration must employ at least one registered electrical worker (REW) and should send the completed application form (Form 1) together with copies of the business registration certificate and the certificate(s) of the employed REW(s) or the employer's certificate of REW(s), and the registration fee to EMSD for processing. The completed application form should be returned to our Customer Services Office in person or sent to us by post or e-mail. The renewal application form (Form 1) can be obtained from our Customer Services Office or any District Offices, or downloaded from http://www.info.gov.hk/forms.

The Electricity (Registration) Regulations stipulate that a REC must renew his/her registration at least one month before and no earlier than four months before the expiry date of the current registration. In order to provide better services, we have been issuing, since the end of last year, letters to remind the RECs to renew their registration that will soon expire.

Note:

To receive the most updated information from us, RECs/REWs should notify us of any change in their correspondence address.

Documents to be Submitted with the Periodic Test Certificate for Fixed Electrical Installations

In the past, some registered electrical contractors/workers (RECs/REWs) failed to provide the necessary documents required for the endorsement of a Periodic Test Certificate (Form WR2). As a result, they had to submit supplementary documents and this would prolong the time required for the endorsement. In order to shorten the processing time, an applicant submitting a Form WR2 should also provide the following information and documents:

1. detailed wiring diagrams (from main circuit to final circuit);
2. records of the test results of the installations;
3. checklists of the electrical installations (For details, please refer to the checklists for the appropriate year in Appendix 10 to the Code of Practice for the Electricity (Wiring) Regulations.);
4. if the periodic test for a part of the installation is conducted by another REC/REW, the main REC/REW should have received the periodic test certificate for that part of the installation (Form WR2(A)) issued by REC/REW concerned and should ensure that the test for that part of the installation has been completed and the test result is satisfactory. The Form WR2(A) must also be submitted together with Form WR2; and
5. a cheque for the endorsement fee for Form WR2.

Additional documents which are useful for our assessment should also be submitted together with Form WR2 by RECs/REWs.

Technical Seminars for Registered Electrical Contractors and Workers Organized by the Electricity Legislation Division (ELD) of EMSD

In late 2001, ELD, the Hong Kong and Kowloon Electrical Engineering and Appliances Trade Workers Union and the Hong Kong Electrical Contractors' Association jointly organized a seminar for the members of the electrical trade. ELD's staff shared their experience with the participants and the seminar was well received. In late 2002, ELD, collaborating continuously with the above Union and Association, organized another seminar on the "Revision of the Code of Practice for the Electricity (Wiring) Regulations, Inspection of Electrical Installations and Regulations for Electrical Products", which aimed at enhancing communication with the electrical trade and updating the technical standards. The seminar was held at the Jockey Club Auditorium of the Hong Kong Polytechnic University on 26 November 2002. It was attended by over 800 members of the electrical trade, who showed great interest in the topics discussed. In the Q&A session, participants raised a lot of questions to gain further technical guidelines. Both of the organizations highly appreciated their members' enthusiastic response. As for the details of the seminar (including the presentation materials and Q&A session), they have been uploaded onto EMSD's homepage for browsing by the public.

E&M Safety Campaign 2002' held by EMSD and 18 Major Organizations

In 2002, EMSD in collaborating with 18 major organizations held the 'E&M Safety Campaign 2002' from the electricity, gas, petroleum, public transport, housing, estate management sectors and trade associations. It was a concerted effort to further enhance Hong Kong people's knowledge on electrical, lifts and escalators and gas safety as well as energy efficiency through different channels and to raise public awareness of E&M safety and energy conservation in their daily life.

E&M Safety Carnival' was one of the highlights of the campaign. It was held at Moreton Terrace Playground in Causeway Bay on 3 November 2002 and attracted the participation of about 6000 citizens. There were 22 game booths set up by various organizations in the venue. The themes of the games were E&M safety and energy efficiency. Participation in these interesting and educational games enabled the public to better understand E&M safety and energy conservation.

Apart from the above major outdoor carnival, 'E&M Safety Campaign 2002' also delivered its messages through a series of interesting and educational publicity and community activities. The publicity activities included a variety show on TVB on 10 November 2002, the drama episode on Commercial Radio 1 between October and November 2002 as well as the comic series in Ming Pao and Sing Dao Daily. In addition, EMSD's professional engineers travelled around shopping centres in the territory to answer public enquiries relating to E&M safety in daily life. Other activities included home visits offering free household electrical safety checks, an energy efficiency survey, a gas safety quiz contest, a lift and escalator slogan competition, community exhibitions and feature talks, etc.

It is estimated that we have been in contact with about 2 million people through the above promotional activities. We hope to bring E&M safety and energy efficiency messages to people from all walks of life and all ages. The campaign ended successfully on 10 November 2002.

Friendly Football Match between ELD and the Hong Kong and Kowloon Electrical Engineering and Appliances Trade Workers Union

Following the seminar for exchanging technical knowledge held at the Hong Kong Polytechnic University on 26 November 2002, ELD and the Hong Kong and Kowloon Electrical Engineering and Appliances Trade Workers Union held a friendly football match at Morse Park, Kowloon on 12 December 2002. Led by Chief Electrical and Mechanical Engineer, Mr. George LING Kam-hoi, the ELD team battled with the trade union team, whose members were mostly young and skilful. They used swift, adaptable tactics which made the ELD team difficult to meet with. Finally, the trade union team won the match with a score of 6 to 3. Both parties agreed that it could enhance our communication through football matches and that similar matches would be held in future.

Contact

Contact Information

Electricity Legislation Division, EMSD, 3 Kai Shing Street, Kowloon, Hong Kong

1823

2895 4929

info@emsd.gov.hk