Reliable Engineering Group

CONSTRUCTION -ELECTRICAL -MECHANICAL

Safety Handbook for Work Site

Monday, May 30, 2016

  •  The Six Step Safety Method
  •  Personnel Protective Equipment
  •  Safety Sign
  •  Safe Manual Handling
  •  Safe Working Above Ground
  •  Electrical Safety
  •  IEE Regulation Fundamental Requirement for Safety

          

 

- The Six Step Safety Method

Think - Be Aware

Many accidents could have been prevented if the injured victim had concentrated on the safety aspects of the job. Thinking about personal or job-related problems while working on or near energized conductors is a one-way ticket to an accident. Always stay alert to the electrical hazards around the work area. 

Understand Your Procedures

Every company has defined safety procedures which are to be followed. Each worker should be thoroughly familiar with all the safety procedures that affect his or her job. Knowledge of the required steps and the reasons for those steps can save a life. 

Follow Your Procedures

In the past, some facilities have allowed the violation of safety procedures in the name of production. Such actions have invariably proven to be costly in terms of human injury and/or death. Violation of safety procedures without good cause should be a discharge offense. What constitutes “good cause” must be decided on a local basis; however, excuses of lesser significance than immediate danger to life should not be acceptable. 

Use Appropriate Safety Equipment

No matter how meticulous workers are, accidents do occasionally happen.

Equipment failures, lightning strikes, switching surges, and other such events can cause shock, arc, or blast. Safety equipment should be used any time workers are exposed to the possibility of one of the three electrical hazards. 

Ask If You Are Unsure, and Do Not Assume

No one should ever get fired for asking a question—especially if it is a safety-related question. Anyone who is uncertain about a particular situation should be encouraged to ask questions which should then be answered by a qualified person immediately and to the fullest extent possible. 

- Personnel Protective Equipment (PPE)

PPE is defined as all equipment design to be worn, or held, to protect against a risk to health and safety. This include most type of protective clothing, and equipment such as eye, foot and head protection, safety harness, life jacket and high visibility clothing.

-Safety Sign

The rule and regulations of the working environment are communicated by written instructions, signs and symbols. All sings in the working environment are intended to inform. They should gave warning of possible danger and must be obeyed. Signs falls into four categories: prohibited activities, warnings, mandatory instructions and safe conditions. 

Prohibited Signs

These are must not do sign. These are circular white sign with a red border and red cross bar. They indicate the activity which must not be done.

Warning Signs

Warning Signs give safety information. These are triangular yellow signs with a black border and symbol. They gave warning of hazard and danger.

Mandatory Signs

These are must do sign. These are circular blue signs with white symbol.

Advisor or Safe Condition Signs

These are square or rectangular green sign with a white symbol. They give information of safety provision.

- Safe Manual Handling

Manual handling is lifting, transporting or supporting loads by hand or by bodily force. The load might be any heavy object, a printer, a VDU, a box of tools or a stepladder. Whatever the heavy object is, it must be moved thoughtfully and carefully, using appropriate lifting techniques if personal pain and injury are to be avoided. 

Consider some ‘ good practice ’ when lifting loads.

  • Do not lift the load manually if it is more appropriate to use a mechanical aid. Only lift or carry what you can easily manage.
  • Always use a trolley, wheelbarrow or truck such as those shown in Fig. 8.5 when these are available.
  • Plan ahead to avoid unnecessary or repeated movement of loads.
  • Take account of the centre of gravity of the load when lifting – the weight acts through the centre of gravity.
  • Never leave a suspended load unsupervised.
  • Always lift and lower loads gently.
  • Clear obstacles out of the lifting area.

  

 

- Safe working above ground

Working above ground level creates added dangers and slows down the work rate of the electrician. Every precaution should be taken to ensure that the working platform is appropriate for the purpose and in good condition. 

LADDERS 

The term ladder is generally taken to include step ladders and trestles. The use of ladders for working above ground level is only acceptable for access and work of short duration (Work at Height Regulations: 2005).

It is advisable to inspect the ladder before climbing it. It should be straight and fi rm. All rungs and tie rods should be in position and there should be no cracks in the stiles. The ladder should not be painted since the paint may be hiding defects.

Extension ladders should be erected in the closed position and extended one section at a time. Each section should overlap by at least the number of rungs indicated below: 

  • Ladder up to 4.8 m length – 2 rungs overlap
  • Ladder up to 6.0 m length – 3 rungs overlap
  • Ladder over 6.0 m length – 4 rungs overlap.

 

TRESTLE SCAFFOLD 

Two pairs of trestles spanned by scaffolding boards provide a simple working platform. The platform must be at least two boards or 450 mm wide. At least one-third of the trestle must be above the working platform. If the platform is more than 2 m above the ground, toe boards and guardrails must be fitted, and a separate ladder provided for access. The boards which form the working platform should be of equal length and not overhang the trestles by more than four times their own thickness. The maximum span of boards between trestles is:

  • 1.3 m for boards 40 mm thick
  • 2.5 m for boards 50 mm thick.

Trestles which are higher than 3.6 m must be tied to the building to give them stability. Where anyone can fall more than 4.5 m from the working platform, trestles may not be used.

MOBILE SCAFFOLD TOWERS 

Mobile scaffold towers may be constructed of basic scaffold components or made from light alloy tube. The tower is built up by slotting the sections together until the required height is reached.

If the working platform is above 2 m from the ground it must be closed boarded and fitted with guardrails and toe boards. When the platform is being used, all four wheels must be locked. The platform must not be moved unless it is clear of tools, equipment and workers and should be pushed at the base of the tower and not at the top.

The stability of the tower depends upon the ratio of the base width to tower height. A ratio of base to height of 1:3 gives good stability.

Outriggers can be used to increase stability by effectively increasing the base width. If outriggers are used then they must be fitted diagonally across all four corners of the tower and not on one side only. The tower must not be built more than 12 m high unless it has been specially designed for that purpose. Any tower higher than 9 m should be secured to the structure of the building to increase stability.

 

 

-Electrical Safety

Residual Current Devices

  •   RCD is the residual Current Device.
  •   The Power supply to all electrical equipment on building and construction sites must be protected by Residual Current Device (RCD) with a maximum rated tripping current of 30mA.
  •   All portable RCDs should be tested daily before use by operation of the test button.
  •   All RCDs while being used on site must be tested by a licensed electrician for tripping current and time each calendar month.
  •   These requirement also applied to RCDs on portable Generators.

Portable Generators

Where portable Generators are used on site, ensure the followings:

  •   Is fully serviceable and has been probably maintained where supplying a fixed installation
  •   Is installed by a license electrician
  •   Is inspected by license electrical inspector before use
  •   Is fitted with a 30mA RCD – where supplying portable tools and equipment. 

Socket Outlet fitted to a portable generators used on a construction site must be protected by residual current devices (RCDs), including those supplying power to a re-locatable site building via and extension lead.

Construction Switch Boards

Construction Switch Boards fitted with residual current device (RCD) use to supply all power on building and construction sites. Temporary switch boards should have:

  •   A door and a locking facility for circuit breakers and RCD which are tested on a monthly cycle
  •   A clear sign on the door stating “Keep closed – leads through bottom”
  •   An insulated recess in the bottom for connecting extension lead
  •   Protection from the weather if used outdoor
  •   Protection against mechanical damage
  •   A clearance at least 1m maintained in front of the board

Extension Leads

 

  • All electrical extension leads should be of a heavy duty type
  • The sheath of electrical extension leads shall not contain color green
  • Lead should not be longer than industrial standard according to their amp rating
  • (Example : 10A electrical leads cannot exceed 35 meters)
  • No extension lead should run from one floor to another on multi levels sites
  • Leads should always be insulated against contact with metal structure.
  • Leads should be raised on insulated stands or hooks to protect them from damage

Make sure that the power tools and electrical leads in use have been properly checked and tagged.

Make sure that electrical leads are lying in water or in contact with metal component.

All 3 pin flat pin plugs and socket used on the extension shall be of the transparent type or non-removable type molded on to the cord.

 

Electrical safety and isolation 

Electrical supplies at voltages above extra low voltages (ELV) – that is, above 50 V a.c. – can kill human beings and livestock and should therefore be treated with the greatest respect. 

As an electrician working on electrical installations and equipment, you should always make sure that the supply is first switched off. Every circuit must be provided with a means of isolation (Regulation 132.10) and you should isolate and lock off before work begins. 

In order to deter anyone from reconnecting the supply, a ‘Danger Electrician at Work’ sign should be displayed on the isolation switch. 

Where a test instrument or voltage indicator such as that shown in Fig. 1.11 is used to prove conductors dead, Regulation 4(3) of EWR 1989 recommends that the following procedure should be adopted so that the device itself is ‘proved’ : 

  • Connect the test device to the supply which is to be isolated; this should indicate mains voltage.                 
  • Isolate the supply and observe that the test device now reads 0 V.
  • Connect the test device to another source of supply to ‘prove’ that the device is still working correctly.
  • Lock off the supply and place warning notices.

 

      

 

Regulation 704.313.4 recommends the following voltages for distributing to plant and equipment on construction sites: 

400 V – fixed plant such as cranes

230 V – site offices and fixed floodlighting robustly installed

110 V – portable tools and hand lamps

SELV – portable lamps used in damp or confined places. 

Portable tools must be fed from a 110 V socket outlet unit incorporating splash-proof sockets and plugs with a keyway which prevents a tool from one voltage being connected to the socket outlet of a different voltage. Socket outlet and plugs are also colour-coded for voltage identification: 25 V violet, 50 V white, 110 V yellow, 230 V blue and 400 V red.

 

Electric shock

 

Electric shock occurs when a person becomes part of the electrical circuit. The level or intensity of the shock will depend upon many factors, such as age, fitness and the circumstances in which the shock is received. The lethal level is approximately 50 mA, above which muscles contract, the heart flutters and breathing stops. A shock above the 50 mA level is therefore fatal unless the person is quickly separated from the supply. Below 50 mA only an unpleasant tingling sensation may be experienced or you may be thrown across a room, roof or ladder, but the resulting fall may lead to serious injury.

To prevent people receiving an electric shock accidentally, all circuits must contain protective devices. All exposed metal must be earthed; fuses and miniature circuit breakers (MCBs) are designed to trip under fault conditions and residual current devices (RCDs) are designed to trip below the fatal level.

When this happens it is necessary to act quickly to prevent the electric shock becoming fatal. Actions to be taken -

  • Switch off the supply if possible.
  • Alternatively, remove the person from the supply without touching him , e.g. push him off with a piece of wood, pull him off with a scarf, dry towel or coat. 

 

- Fundamental Requirements for Safety

 

 

IEE WIRING REGULATIONS (IEE REGULATIONS PART 1 AND CHAPTER 13) 

It does not require a degree in electrical engineering to realize that electricity at low voltage can, if uncontrolled, present a serious threat of injury to persons or livestock, or damage to property by fire. Clearly the type and arrangement of the equipment used, together with the quality of workmanship provided, will go a long way to minimizing danger. The following is a list of basic requirements: 

1. Use good workmanship.

2. Use approved materials and equipment.

3. Ensure that the correct type, size and current-carrying capacity of cables are chosen.

4. Ensure that equipment is suitable for the maximum power demanded of it.

5. Make sure that conductors are insulated, and sheathed or protected if necessary, or are placed in a position to prevent danger.

6. Joints and connections should be properly constructed to be mechanically and electrically sound.

7. Always provide overcurrent protection for every circuit in an installation (the protection for the whole installation is usually provided by the Distribution Network Operator.

[DNO]), and ensure that protective devices are suitably chosen for their location and the duty they have to perform. 

8.    Where there is a chance of metalwork becoming live owing to a fault, it should be earthed, and the circuit concerned should be protected by an overcurrent device or a residual current device (RCD).

9.   Ensure that all necessary bonding of services is carried out.

10. Do not place a fuse, a switch or a circuit breaker, unless it is a linked switch or circuit breaker, in an earthed neutral conductor. The linked type must be arranged to break all the line conductors.

11. All single-pole switches must be wired in the line conductor only.

12. A readily accessible and effective means of isolation must be provided, so that all voltage may be cut off from an installation or any of its circuits.

13. All motors must have a readily accessible means of disconnection.

14. Ensure that any item of equipment which may normally need operating or attending by persons is accessible and easily operated.

15. Any equipment required to be installed in a situation exposed to weather or corrosion, or in explosive or volatile environments, should be of the correct type for such adverse conditions.

16. Before adding to or altering an installation, ensure that such work will not impair any part of the existing installation and that the existing is in a safe condition to accommodate the addition.

17. After completion of an installation or an alteration to an installation, the work must be inspected and tested to ensure, as far as reasonably practicable, that the fundamental requirements for safety have been met.