Electrical

Equipment Tester

As a result of a grant from the Dept. of Families & Communities, TADSA has purchased an electrical equipment tester.  Training was also undertaken by Travis, Tony and Richard, who are now qualified to test and tag electrical equipment.  The tester will be used to test any mains powered project before delivery to clients.  We will also be able to test our own in-house equipment, as required under OH&S laws.  We will be organising testing sessions at the TADSA office, where technical members can bring their own electrical tools for testing and tagging.   Sessions will be organised at a convenient location for our members in the southern areas.  More information forthcoming.  Our thanks to the Department for supporting us in this way.

Residual Current Devices (RCDs)

Do I need an RCD?

Most work places have some moveable electrical equipment that is plugged into a socket outlet and therefore will require an RCD.  In a new installation the RCDs are   required to be the non-portable type while portable and non-portable types are  acceptable in other locations.

 Many office type workplaces however, may only require RCDs for “cleaning and kitchen equipment” and perhaps one or two other pieces of equipment as discussed newsletter 115 & 116.  In these cases, the situation can often be solved by the use of a couple of portable RCDs, costing much less than fitting non- portable types to the switchboard.

If I require an RCD, who is responsible for providing the RCD, myself or the landlord?

1. Existing Electrical Installations
   The person who has control over the provision and use of the RCDs is the responsible person. In the case of an existing installation, there is only a mandatory requirement for portable RCDs.  There are no mandatory requirements for non-portable RCDs in these installations.
   
   The landlord has no control over the use of any “moveable electrical” equipment and the use of portable RCDs in these situations.  Only you have control over the use of this equipment and the portable RCDs.  It is therefore your responsibility,  the employer or the occupier, to provide and ensure that RCDs are used.
   
   
2. New Installations
   If the building was constructed after 1^st April 1996 and the supply of electricity was connected to the installation after this date, it would be up to the building owner to ensure there is non-portable RCD protection, in general, throughout the              building.  There may be some circuits for which it is undesirable to have RCD protection (eg. refrigerators).  For these circuits and outlets, it is necessary for them to be clearly identified and to have procedures in place to ensure they are not used for other applications that would require RCD protection.

What constitutes a “New Installation” for the requirements to provide non-  portable RCDs?

A new installation is considered to be any installation that requires a new distribution or switchboard to be installed regardless of the age of the building. This is based on the intent of the OHSW regulations regarding the application of portable and non-portable RCDs.

If I engage a tradesperson or cleaner to do work on my premises, who is responsible for providing and ensuring that RCDs are used?

You both have a responsibility, however, you must make the tradesperson or cleaner aware that the building is not protected by an RCD and inform them that they will be required to provide their own.  Provided you make a reasonable attempt to ensure that          this is known and understood, and as far as you have control, ensure they are used, then it would be the tradespersons or cleaner’s responsibility.

We would also expect the employer of any cleaner or tradesperson who regularly attends different work places to have identified this as a possible hazard and provide portable RCDs for their use.

I hire out electrical equipment, do I need to provide an RCD with that equipment?

It is the responsibility of the person who has hired the equipment to provide the RCD protection. They have control over its use, however you have a responsibility to ensure that the equipment is not defective and electrically safe.  It is recommended that you advise the hirer that an RCD may be required with this equipment.

What type of RCDs can I use? 

RCDs can either be portable or non-portable, of which there are several types.  In new installations non-portable types are required, while either portable or non-portable can be used elsewhere.

• Portable – there are three types of portable RCDs:
  those that plug directly into the socket outlet and the appliance or cord plugs into the RCD not unlike a “double adaptor”
  
  Those that are connected permanently to the equipment’s cord in place of the original three pin plug. These ensure that the equipment is never used without the RCD and may discourage theft of the RCD.
  
  Multi outlet types. These usually have a short extension cord with 2 to 4 power points combined with an RCD in a small box.  They are useful if more than one piece of equipment needs to be supplied through the RCD at one time.
  
  
• Non-portable – there are two types of non-portable RCDs:
  Switchboard mounted types which can provide protection for several circuits.  These provide one of the best forms of RCD protection.
  
  Socket outlet types, in which the RCD is mounted in a standard power point.  They provide protection not only for that power point but other power points “down stream” and on the same circuit as the RCD power point.  These can provide a cost effective solution in which only specific areas need RCD protection such as office, kitchen or lunch rooms.

Do I need to test RCDs? 

Yes.  A portable RCD needs to be tested before it is first used on any day by pressing the test button and a complete test in accordance with AS3760 at intervals specified therein.  (Commercial environments every 2 years, factories every year, construction sites every 3 months etc.).

Non-portable RCDs need to be tested every 3 months by the built in button, and in accordance with AS 3760’s procedures every 3 years.

CAUTION – An RCD is not a “cure-all” for poor work practices.  In many of the fatal electrical accidents, an RCD would have saved a life.  However, RCDs are not “fool proof” and under some circumstances they will not provide protection. 

Protection is not provided where current flows from the active wire through the person to the neutral and there is no leakage to earth.  Protection is not provided where the source of the electric shock is “up-stream” of the RCD protection.  For example, using an electric drill which is protected by a portable RCD.  If you accidentally drill into an electric cable in the wall, because the source of the current is up-stream of   the RCD it will not afford any protection to the operator.

This is one of the reasons why non portable RCDs are required on new installations and are preferred over portable types wherever possible, however they are not a substitute for good safe work practices.

- from Workplace Services

Preventing Electrical Shock From Power Tools and Electrical Leads

(Article from WorkSafe Victoria)  

Workers using portable power tools and electrical leads that are electrically faulty or damaged, may suffer electrical shock, which could result in death, heart problems, internal organ damage or burns.

When using electrical leads and power tools –

• visually inspect prior to use – don’t use equipment if it has been modified or damaged
• plug tools into socket outlets that are protected by a residual current device (RCD) or use a portable RCD (RCDs are also known as safety switches).
• plugtop type RCDs should not be fitted to power tools or equipment, as the RCD cannot be readily tested.
• ensure power circuits are protected by the appropriate rated fuse or circuit breaker to prevent overloading
• if the circuit keeps overloading, don’t increase the fuse rating as this creates a fire risk due to overheating
• arrange electrical leads so they will not be damaged.  Avoid running across the floor or ground, through doorways and over sharp edges.  Use lead stands or insulated cable hangers to keep leads off the ground
• don’t use leads and tools in damp or wet conditions, unless they are specially designed for those conditions.
• to ensure RCDs continue to provide shock prevention, implement an electrical testing regime.

A Personal Experience – This person (let’s call him Joe), had a very narrow escape a while back, when he picked up a power cord that had been left by a previous user in his workplace, plugged it in, then walked with the cable in his hand, unraveling it as he went along.  He reached the end of the cord, completely unaware that someone had cut the end off!  Joe received a severe electrical shock, but had the presence of mind to fling the cord around a nearby verandah post, which wrenched the live cord out of his hand, possibly saving his life.  Joe was left lying on the ground suffering from shock, but thankfully, survived his ordeal.  He now checks that the cord he is using is safe – damaged electrical cords need to be safely disposed of or repaired immediately.

 

Don’t get Electrocuted by Your Welding Machine 

(article supplied by Work Cover Corporation)

They say “it’s the volts that jolts”.  But experiments prove that an electric current of only about 50 milliamps lasting for only one second can have a severe, possibly fatal, effect on the human body.  The resistance of the human body measured from hand to hand, or hand to foot is about 1,000 ohms, which means that it only takes about 50 volts differential to send 50 milliamp current across this resistance.  That is why 32 volts or less is classified as ‘extra low voltage’ in AS 3000, and a voltage between 32 and 250 volts is classified as ‘low voltage’. 

But don’t be misled into thinking that because it is called low voltage that it is relatively safe.  Voltages even as low as 50 volts for very short periods can be fatal.  And these experimental calculations assume hand to hand or hand to foot resistance.

What if the actual environmental conditions when working with electrical equipment, are much worse than those assumed in the above experiments.  Take, for example, electric arc welding.  You can often be working in a confined space and often in a cramped position.  The workspace might be hot and poorly ventilated.  You are uncomfortable and sweaty.  If you lean directly against the body of the workpiece, say, with your damp clothed shoulder, or even upper arm and your opposite hand comes into contact with the live welding electrode, you could have 80 volts from the secondary side of the welding transformer passing through your body, not dry hand to dry hand or foot, but through a shorter resistance from hand to opposite shoulder and with better contacts caused by the sweat and damp clothing.  And your heart is directly in the path.

Although manual metal arc welding (MMAW) can be performed perfectly safely, there are circumstances when there is substantial risk of electric shock.  It is obvious that poorly maintained or badly connected equipment may be extremely hazardous.  What is not so well known is that an electric shock from a welding machine can have such serious consequences.  MMAW is risky because the electrode is changed frequently while the electrode holder is electrically live. –

Many welders admit to suffering a shock if they simultaneously touch live parts of the electrode holder and the workpiece.  In most cases the consequence is only an unpleasant tingle, but sometimes the shock can lead to muscular spasms causing a fall from a height or the injury by victim striking against something.  Death by electric shock is rare, but is a real possibility.  Fuses and earth leakage devices will have no effect on reducing this hazard.

Factors which affect the severity of the shock are:

• The open circuit voltage of the welding machine, and whether the machine supplies alternating or direct current (AC is 2 to 3 times more dangerous than DC, because AC causes muscles to grip tightly).
• The pressure the victim exerts on the electrode and workpiece, because increased pressure means better contact.
• The effectiveness of insulation (gloves etc.) at the contact points, the presence of moisture from rain, perspiration or other source.
• Which parts of the body are in contact with the work and electrode, (the worst current flow path is between the left hand and torso.
• The susceptibility of the victim to shock, which is dependent on health and other factors.
• Precautions against this risk include use of properly maintained equipment, correct protective equipment and sound work practices.

To avoid electric shock –

• avoid bare skin contact with the electrode, and either
• prevent contact with the workpiece, or
• select a low voltage welding machine.

Avoiding Contact with the Electrode - Handle the electrode holder carefully.  Use dry welding gloves on both hands when handling the electrode holder or gun, particularly when changing electrodes.  Do not hold electrodes under the arm pit while changing them.  Do not wrap the electrode lead around yourself.  Remove stub ends and part used electrodes from the holder immediately welding is finished.

Ensure the electrode lead is live only while you are welding.  Do not drag live cables to the work position.  Turn off the power when welding is finished or during breaks.

Avoiding Contact with the Workpiece - Avoiding contact with the electrode is not sufficient, because an accidental brush with the electrode tip may also cause a shock.  Where possible, avoid contact with the workpiece.  Where possible, cover exposed parts of the workpiece, workbench and concrete or metallic flooring with insulation such as heat resisting blankets, rubber matting or wooden duckboards.

Wear appropriate safety clothing.  As a minimum, this should comprise heavy non-synthetic shirt and trousers or overall, rubber soled safety shoes and welding gloves.  Additional protection such as leather jacket, apron, knee pads and cap provide useful extra protection, although their brass fasteners tends to negate their electrical insulation properties.

Keep the work area, insulation and clothing dry.  In hot conditions, the risk of electrocution is increased because of clothing and equipment being soaked in perspiration.  The risk is far worse in closed environments, such as tanks or vessels, particularly when these are exposed to the sun’s heat.  Take frequent rest periods, during which time dry off equipment and clothing.  Frequently change or alternate gloves and protective clothing to avoid perspiration accumulating.  Ventilate or if possible, air condition the work area.  Ventilation will help dry perspiration and cool the body.  Cool the face with an air fed mask.  If clothing becomes saturated with perspiration, it must be changed.

Welding Machines for Electrically Hazardous Environments

If insulation of the welder from the work-piece cannot be guaranteed, the environment must be considered as electrically hazardous.  Such environments are whenever the welder has to work on or in the work-piece.  Freedom of movement is often restricted, so that the welder is forced to perform work in a cramped (kneeling, sitting or lying) position.  The hazard is compounded in wet, damp or hot locations, where humidity or perspiration considerably reduces the electrical resistance of the human body and the insulating properties of accessories.  Examples include shipbuilding work, inside vessels or pipes, in damp trenches, large steel structures and underground mines.  The hazardous environment does not need to be a confined space.

If the environment is considered electrically hazardous, then the welding equipment should have a safe voltage.  AS/NZS 3195 covers portable welding machines for both hazardous and non-hazardous environments.  The maximum OCV of direct current welding machines for both hazardous and non-hazardous environments is 113 volts.  Alternating current machines for hazardous environments should have a maximum OCV of 48volts rms instead of the normal requirement of 80 volts.  Portable welding machines for hazardous environments carry a label indicating this.

In line with international standards, there are moves to adopt similar requirements for non-portable welding machines currently covered by AS 1966.  Until such measures are adopted it is wise to measure the OCV of AC machines to determine their suitability for use in hazardous environments.  Voltage limiting safety devices are available which may be fitted to any welding machine.  Such a device automatically limits the voltage to less than 25 volts and only applies the full OCV when the electrode is struck.

This information is provided to offer guidance on a particular aspect of legislation.  It is not to be taken as a statement of law and must not be construed to waive or modify any legal obligation.