Editor's Notes

Feature Article

Analysis of Electrical Incidents

Members of the electrical trade may be aware that there have been a number of serious electrical incidents in recent years in Hong Kong, resulting in fatalities and injuries (including those involving electrical workers) from suspected electrocution. In view of the increasing trend of incidents involving injuries arising from electric shock, we are going to analyse three of the incidents that took place in 2016 through this feature article with a view to raising trade members' alertness and safety awareness when carrying out electrical work, and preventing electrical accidents from occurring.

Incident 1

The incident occurred at a site where demolition works were being carried out. A demolition worker died after receiving an electric shock during the removal of a wire. An investigation by the Electrical and Mechanical Services Department (EMSD) found that although the earth leakage circuit breaker located at the downstream portion of the circuit concerned had been isolated, the fuse upstream was still connected to power supply, so the circuit was still energised. When the worker was trying to cut the still energised wire manually with a pair of metal scissors and with his hands unprotected, the other exposed parts of his body touched the earthed metal part, resulting in the electric shock incident.

The causes of the incident include:

1. The wire to be removed and the relevant circuit were not tested and confirmed to have been isolated from power supply before the commencement of works; and
2. Checking on whether the circuit in the works area were live and earthed or not was not carried out before the commencement of works.

Incident 2

The incident happened in a switch room where addition and alteration works were being carried out. A registered electrical worker (REW), while checking a newly-installed circuit, touched the exposed live parts accidentally and was electrocuted. He then fainted and was sent to hospital. It was fortunate that a worker at the scene noticed the incident and used a mallet to push the injured worker away from the live parts, otherwise the consequences might have been more serious. An investigation by EMSD found that a circuit control box in the works area, which was still energised, had its cover removed, leading to the exposure of live parts. In carrying out the live work, the worker concerned touched the exposed live parts accidentally, resulting in the electric shock incident.

The causes of the incident include:

1. Power supply to the relevant circuit was not cut off and isolated during the course of the electrical work; and
2. When carrying out work in the area where the live parts were located or the low-voltage live parts could be touched directly or indirectly, sufficient precautions were not taken to avoid danger.

Incident 3

The incident occurred in a building where addition and alteration works were being carried out. An REW, while carrying out work at a false ceiling, received an electric shock and passed out. He was sent to hospital and certified dead afterwards. An investigation by EMSD found that there was an exposed live device inside the false ceiling where he was working, and it was therefore suspected that he had come into contact with the exposed live device accidentally while touching the earthed metal part of the false ceiling, resulting in the electric shock incident.

The causes of the incident include:

1. There was an exposed live device inside the false ceiling; and
2. The metal part and device were not tested to ascertain whether they were live or not before the commencement of works.

The causes of the above incidents involve improper work process, live work and improperly installed device. In this regard, here are some suggestions on how to prevent electrical accidents from occurring:

1. The electrical work should be carried out by an REW of the appropriate grade or a worker under his supervision.
2. An REW shall ensure that safety precautions are taken to prevent danger arising from electrical wiring work done by him or under his supervision.
3. The workplace should have sufficient lighting.
4. The condition of the relevant tools and instruments should be checked before carrying out the electrical work. In case of damages or defects, one should stop using them immediately and inform the person in charge.
5. Check whether the relevant protective devices are operating properly before carrying out the electrical work.
6. Check whether the circuits in the works area are live or not before carrying out the electrical work.
7. The metallic parts (including exposed conductors) in the working environment should be tested with instruments to see if they are dead before carrying out the electrical work, while ensuring that appropriate personal protective equipment (e.g. insulating gloves) and tools are used (see Appendix 14 of the Code of Practice for the Electricity (Wiring) Regulations for details).
8. Avoid carrying out work under live conditions. Before carrying out the electrical work, switch off, isolate and lock out the power supply to the installation and its control circuit; test the metallic parts of the installation to see if they are dead; ensure that the circuit is not energised; and post appropriate warning notices.
9. If the switching off of power supply may affect the daily operation of the building, registered electrical contractors should discuss with the owners or property management company before the commencement of work. Arrangements should be made as far as possible to switch off the power supply to the installations, so that the electrical work can be conducted when the installations are not energised.
10. If the work has to be performed under live conditions (such as testing), electrical safety assessment on the live work should be made by those responsible for the assessment before carrying out the work (see Appendix 15 of the Code of Practice for the Electricity (Wiring) Regulations for details).
11. Before carrying out building demolition works, one should arrange for the power company to cut off the power supply to the building and ensure receipt of the notice of termination of power supply issued by the power company. After confirming that the power company has cut off the power supply, the electrical installations/equipment concerned should be inspected again to ensure that they are not energised before the commencement of demolition works.
12. Avoid standing on the ladder to carry out the electrical work because in this way, even a slight electric shock may cause the worker to lose balance and fall from height.
13. A fixed electrical installation shall, after completion (including any work completed after repair, alteration or addition) and before it is energised for use, be inspected, tested and certified by an REW to confirm that the requirements of the Electricity (Wiring) Regulations have been met.

News-in-brief

News-in-brief 1 - Outstanding Registered Electrical Worker Awards Scheme 2017

As part of the effort to continuously enhance the professionalism and safety standard of the electrical trade, and to commend the electrical workers with outstanding performance in the trade, EMSD once again collaborated with trade associations to organise the Outstanding Registered Electrical Worker Awards Scheme 2017 to commend the outstanding trade workers. Award recipients will not only receive great prizes, but also have the opportunity to share their daily work experience and insights with other trade members. Registered electrical workers are encouraged to participate actively. For details, please browse the following web page: Outstanding Registered Electrical Worker Awards Scheme 2017

News-in-brief

News-in-brief 2 - Permit-to-Work (Continued)

In the last issue of Electricity News, we covered the roles and responsibilities of Responsible Persons and Persons in-charge in the permit-to-work system. In this issue, we will further illustrate with real examples:

Let's say a 300A TPN MCCB inside a switch room requires replacement in an electrical work. According to codes 4G(1)(c) and (e) of the Code of Practice for the Electricity (Wiring) Regulations (Code of Practice), the upstream 800A 4P ACB must first be isolated to ensure that the electrical installation is dead for the work to be carried out safely. In addition, the Responsible Person assigned by the owner of the fixed electrical installation shall issue the permit-to-work and submit the signed copy to the Person-in-charge to ensure that the installation has been rendered dead, isolated, discharged and earthed (if necessary).

Since amendments have been made to Part 1 of the permit-to-work, here we will demonstrate how to fill in the amended version of Part 1.

Please click here for the demonstration

As the work involves the replacement of a 300A TPN MCCB inside the switch room, the "Low Voltage Fixed Electrical Installation" and "MCCB" boxes should be selected in the "Electrical Equipment To Be Worked On" section of Part 1(1).

Select "Switch Room" and "Replacement" respectively in the "Location of Electrical Equipment" and "Details of Work To Be Done" sections in Part 1(2) and (3).

In accordance with the requirements of the Code of Practice, the upstream 800A 4P ACB must be isolated with lockout and tagout. Therefore, the "4-pole ACB" option should be selected for the "Exact Point Where Electrical Equipment Is Isolated" section in Part 1(4) and "800A 4P ACB (ACB #K-0001)" should be written in answer to both the "Safety Locks Applied At" and "Caution Notices And Danger Notices Have Been Posted At" sections in Part 1(6) and (7).

Lastly, the Responsible Person is reminded to sign Part 1 of the permit-to-work and submit the signed copy to the Person in-charge for signing in acknowledgement of the receipt.

News-in-brief

News-in-brief 3 - Effective Date of Code of Practice for the Electricity (Wiring) Regulations (2015 Edition)

It has been quite some time since the publication of the Code of Practice for the Electricity (Wiring) Regulations (2015 Edition), and you should already be fairly familiar with the content of the new Code of Practice.

According to code 1 of the Code of Practice, electrical installations (including those that are newly installed and altered) completed and connected to electricity supply on or after 30 November 2017 must comply with the new requirements. In view of this, if you are in the process of designing any electrical work with its completion date and the date of connection of the electrical installations to electricity supply estimated to be on or after 30 November 2017, you should now consider designing the work in accordance with the Code of Practice (2015 Edition).

Within the grace period, EMSD will attend the relevant technical seminars at the invitation of the trade unions, associations and organisations to introduce the major amendments of the new Code of Practice. For those who are interested in learning more about the new amendments, please keep an eye on the relevant arrangements and attend the seminars.

News-in-brief

News-in-brief 4 - Continuing Professional Development Scheme for Registered Electrical Worker - Technical Knowledge about Electrical Works

The Continuing Professional Development (CPD) Scheme for Registered Electrical Worker (REW) has been included as a requirement for renewal of registration since 1 January 2012. According to the CPD Scheme, REWs applying for each registration renewal are required to have completed two modules of training, including Module (1): Legislative and Safety Requirements and Module (2): Technical Knowledge, before submitting their renewal application.

The CPD Scheme has been widely supported by the trade with spectacular achievements since its launch. Apart from advising you to complete the above two modules of training before applying for each registration renewal, we would also like to take this opportunity to encourage you to refresh your knowledge, from time to time, through the enrolment for seminars or training courses related to electrical works which are organised by EMSD or conducted by recognised trainers in order to enhance the technical know-how of individuals and the electrical engineering industry as a whole.

We will continue to discuss with the related trade organisations to organise more different types of seminars or training courses on up-to-date technical knowledge about electrical works for REWs. For details of the CPD Scheme and the latest information on the relevant seminars and training courses, please visit our web page.

News-in-brief

News-in-brief 5 - Maintenance of Generating Facility

Under section 22 of the Electricity Ordinance, an owner of a generating facility shall (a) maintain the generating facility in continuous safe working order; and (b) display at the facility a notice showing the name and registration number of the registered electrical contractor employed for the purpose of item (a) if the facility:

1. has been registered with the Director of Electrical and Mechanical Services (the Director);
2. is used in construction work as defined and regulated under the Factories and Industrial Undertakings Ordinance (Cap 59);
3. forms part of an electrical installation that requires a periodic test certificate to be submitted to the Director under the Electricity Ordinance (such as an emergency standby generator); or
4. only supplies electricity to an electrical installation that is owned by the owner of the generating facility.

As such, the owner of the generating facility is reminded to display at the facility a notice showing the name and registration number of the registered electrical contractor who carries out maintenance on the facility.

News-in-brief

News-in-brief 6 - Certificate of Registration of Electrical Worker

A registered electrical worker shall take note of the following when carrying out electrical work:

• Before carrying out the electrical work, he should check whether his electrical worker registration is still valid and ensure that the electrical work to be conducted is of the grade and type of work permitted under his registration;
• In the course of the electrical work, he should carry with him the Certificate of Registration of Electrical Worker (as shown in the picture on the right) issued by EMSD and produce it for inspection upon enquiry by the client;
• Other employment certificates, such as certificates in respect of electrical workers at construction sites issued under the Construction Workers Registration Ordinance or employment certificates on electrical work issued by individual trade organisations, are not applicable. You are advised that any person who carries out electrical work, irrespective of whether it is undertaken at home or at a shop or a site, without a valid Certificate of Registration of Electrical Worker as shown above is in breach of section 31(1) of the Electricity Ordinance and shall be subject to prosecution.

News-in-brief

News-in-brief 7 - Tips on Safe Use of Mildly Flammable Refrigerant R32

In response to climate change, the world is committed to reducing greenhouse gas emissions and phasing out the use of high Global Warming Potential (GWP) gases. At present, refrigerants that are widely adopted in domestic air conditioners usually have high GWP. Leakage of these refrigerants to the atmosphere will accelerate global warming. So individual manufacturers of domestic air conditioners have opted for lower GWP refrigerants, but some of which may have mild flammability. A notable example of mildly flammable refrigerants is R32.

Domestic air conditioners using mildly flammable refrigerants should be labelled with a "Flammable" symbol for identification. Before purchasing such products, consumers should pay particular attention to the restrictions on use as specified by the manufacturers, such as requirements on minimum room area and minimum installation height, etc. They may check with the agents or suppliers for relevant restrictions. Installation, inspection or maintenance of the products should be carried out in compliance with the specified restrictions by the agents, suppliers or technicians who have experience in mildly flammable refrigerants.

Since electrical trade practitioners may have the opportunity to engage in the installation, inspection or maintenance work of domestic air conditioners, the employer concerned should provide relevant training and equipment to his staff and effectively supervise them to carry out such work with good workmanship and under safe procedures with a view to protecting the work safety of the staff and the safety of others.

News-in-brief

News-in-brief 8 - Points to Note by Competent Persons

Please apply for renewal in time and notify EMSD of any change in the name/address within the specified time limit.

Moreover, under the Electricity Supply Lines (Protection) Regulation, if there is any change in the name or address of a competent person, a written notice shall be given to EMSD of the changed particulars within 21 days after the change takes place. Those who fail to comply with this requirement commit an offence and are liable to a fine.

Enquiries

For any enquiries, the applicant may contact the Registration and Permit Office of EMSD at G/F, 3 Kai Shing Street, Kowloon, Hong Kong from 9:00 am to 5:15 pm, Mondays to Fridays (closed on Saturdays, Sundays and Public Holidays), or call the 1823 Citizen's Easy Link.

News-in-brief

News-in-brief 9 - Use of Circuit Breakers Equipped with Lockable Function

Electrical Safety Quiz

(Ans: 1d, 2b, 3d, 4d, 5b)

Readers' Feedback and Update

We look forward to receiving your valuable feedback about this newsletter for continuous improvement. Please complete this feedback and update form and return it to the Electricity Legislation Division of EMSD by post, fax or e-mail (contact details at the bottom of this page) on or before 30 September 2017.

Contact Information

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

Tel : 1823

Fax : 2895 4929

Email : info@emsd.gov.hk