Category: Safety Switches

RCDs V’s Circuit Breakers

Posted on by Prolux

What is the difference between an RCD and a Circuit Breaker?

Sometimes there is a misconception regarding the difference between an RCD (Residual Current Device) and a Circuit Breaker. Let’s explain…

An RCD is typically known as a Safety Switch, designed to protect against electrocution and will detect any disruption of electrical flow through an electrical circuit. If the flow of electricity returning through the circuit does not exactly match the amount of electrical flow entering the circuit, the RCD will ‘switch off,’ due to electricity leakage (leakage to earth). The RCD ‘thinks’ that the leakage to earth is electricity going through a person and into the ground, therefore switching off the power supply to prevent any form of an electric shock.

A Circuit Breaker on the other hand is an electrical switch, designed to protect an electrical circuit from damage, caused by an excess electrical flow (current draw), due to an overload or short circuit.

Circuit Breakers will not ‘switch off’ the power to the circuit in the event of an earth leakage fault. They will activate by switching the power ‘off,’ in the event of a high current fault, short circuit or overload, such as when too many appliances are plugged into a single power point, or when one of the appliances is faulty.

 

How does an RCD work?

An RCD constantly monitors the current flowing in both the ‘active’ and ‘neutral’ wires supplying a circuit or an item of equipment; which under normal circumstances should be an equal current flow in both wires. When an earth leakage occurs, it creates an imbalance, the RCD detects this and will automatically ‘cut off power’ before damage or injury transpires. RCDs must disconnect power supply (switch off) within 30 milli-seconds of leakage detection. RCD’s in Patient Protected Areas (such as hospitals) must ‘cut off power’ within 10 milliseconds of detecting a leakage.

“Even a 30mA of current could be enough to cause a person to go into cardiac arrest or cause irreversible damage to their body.”

Fixed RCDs can be identified by the ‘Test’ button. Portable RCD’s (plug into a socket outlet) and Socket Outlet RCD’s (incorporated into an outlet) also have a ‘Test’ button. If you can’t identify a ‘Test’ button, then it’s likely to not be an RCD.

 

Are RCDs compulsory? Do all circuits require RCDs?

 All circuits rated 32A or less that are supplying socket outlets, lighting, hand held equipment or equipment that present as an increased risk of an electrical shock must be RCD protected (unless labelled otherwise for a specific item of equipment). All new circuit installations require RCDs to be installed, or when the circuit installations require additional protection (30 Amps +).

For Commercial and Industrial installations RCDs must be installed within a switchboard at which the final sub-circuit originates. This is a mandatory requirement of the AS/NZS 3000:2018 Wiring Rules Standard. Even though the standard calls for RCDs on all sub-circuits up to and including 32 Amps, exemptions apply. If a single item of electrical equipment (e.g. light) which isn’t RCD protected is to be replaced with an equivalent item within the same location, then the exemption may apply.

When switchboards are altered or replaced, RCDs are required for final sub-circuits. RCDs are also required to protect socket outlets when they’re added to an existing circuit. However, RCD protection only needs to be installed at the origin of the additional wiring. When all circuit protection within a switchboard is replaced, then additional RCD protection is required for the final sub-circuits supplied by that switchboard.

 

Looking to upgrade a switchboard? Call Prolux Electrical Contractors on 1800 800 880 and let us ensure your commercial and industrial buildings run safe and efficiently. 

Electrician suffers electric shock whilst working live

Posted on by Prolux

How does an electric shock occur?

An electric shock occurs when a person comes in contact with an electrical energy source. Physical contact with energised wiring or devices is the most common cause of an electric shock. Like water and metal, the human body is a conductor of electricity and exposure to electrical energy can result in a shock or death (electrocution).

What are the effects from an electric shock?

The effects from an electrical shock will depend on the type of current, how high the voltage was, how the current traveled through the person’s body, their overall health and how quickly the person was treated. While any amount of current over 10 milliamps (0.01 amp) is capable of producing painful to severe shock, currents between 100 and 200 mA (0.1 to 0.2 amp) are lethal.

Even someone with minor injuries or no symptoms at all should be checked by a doctor for internal injuries. Trauma may include burns (the shock can cause a burn where the current enters and leaves the body), muscle pain, contractions, seizures and unconsciousness. The electricity can not only injure blood vessels, nerves, and muscles, but internal organs can also be affected (heart and lungs), resulting in an irregular heartbeat, breathing difficulties and organ failure. You might not see all the damage the shock has caused for up to 10 days after the shock.

 

Take this example of an electrician who suffered an electric shock whilst working live, putting his life at risk…

An electrician was working on site installing Residual Current Devices (RCD’s) for approximately 20 switchboards. No live work was to occur in relation to these contracted works. The IP (injured person) had received training on company Job Safety Analysis (JSA) and Safe Work Method Statement (SWMS) prior.

The IP had completed a full isolation and installation of the switchboard and had re-energised the switchboard to commence testing the RCD. Prior to testing, the IP noticed part of the duct cover wasn’t fully connected and reached inside the live switchboard to press it back into place. The IP made contact with a live copper component and subsequently received an electric shock to the hand. A call was made to 000 and the IP was taken to hospital for assessment and treatment.

Post incident the switchboard was made safe by a colleague.

The contributing factors which lead to the electric shock was that the IP did not re-isolate the switchboard before placing their hand into the live switchboard.

No live work was to take place, the electrician breached the company’s Live Work Policy, Safe Work Method Statement and pre-start JSA by energising the switchboard and continuing to work within the switchboard.

This example highlights the importance of effective isolation regardless of the duration of the task at hand.

When is it ok to work live?

Other than unavoidable testing and commissioning functions, all electrical work should be carried out on de-energised/isolated installations and equipment.

If you are working live then you are risking your life.

To work live you must have management approval, along with a well documented SWMS, appropriate tools, testing equipment, personal protective equipment and an electrical safety observer must be used when there is no reasonable alternative to performing energised electrical work (live work).

Safety observers must be trained in low voltage switchboard rescue and CPR, they must be hightened to ensure incidents don’t occur in the first place. A safety observer must have a clear understanding of the work being undertaken and the associated risks associated, be in a position to clearly observe the work (one task at a time) and warn of any dangers, and stop any work before the risks become too high or compromises their role as a safety observer.

Safety comes first for all electrical works

Electricians must take reasonable care of their own health and safety, and the health and safety of people who may be affected by their acts or omissions within the work place. Employees must cooperate with their employer and carry out the employer’s actions to comply with their OHS obligations, including JSA and SWMS. The Electricity Safety Law, which is regulated by Energy Safe Victoria (ESV), requires all electrical circuits or electrical equipment handled in the course of electrical work to be disconnected from the electricity supply, unless adequate precautions are taken to prevent electric shock or other injuries. Safe working practices are paramount.

Hints for Electricians to work safely on switchboards

  • De-energise and isolate the switchboard or circuit to be worked on
  • Test to ensure all parts are de-energised before restarting work
  • Ensure a Safe Work Method Statement is developed and adhered to
  • Ensure apprentices are adequately supervised
  • If the power cannot be turned off, reschedule the work to a time when the power can be isolated

No one should risk their life, or the lives of work mates, for the sake of saving time or inconvenience.

AS/NZS 3000: 2018 Wiring Rules Standard for RCDs in Commercial Buildings

Posted on by Prolux

New clause preventing electric shock in Commercial Buildings

Effective January 1st, 2019 was the new edition of the AS/NZS 3000 Wiring Rules Standard (Electrical Installations), which outlined over 200 changes and expanded upon the coverage of electrical installations. The changes have taken into account new technologies, new products and improvements in safety, whist clarifying on the previous versions ambiguous requirements.

One of the major changes to the AS/NZS 3000: 2018 is the Residual Current Devices (RCD) requirements for the protection of sub-circuits and relating alterations and repairs (clause 2.6.3.2.3).

Everyone in the industry is bound by them and every customer is the beneficiary.

In commercial and industrial environments, all 32 Amp outlets and below need to be protected by an RCD. The new AS/NZS 3000 wiring rules require additional RCD protection:

  • 30mA RCDs shall be installed on all final sub-circuits supplying socket outlets and lighting below 32 Amps
  • 30mA RCDs should be installed on all final sub-circuits supplying 32 Amp fixed wired equipment
  • 30mA RCDs shall be installed on all final sub-circuits supplying 32 Amp fixed wired equipment that may classify as an increased risk of electric shock e.g. wet or high risk areas.

The RCD requirements for final sub-circuits has increased to 32 Amp, from the previous 20 Amp to provide personal protection from electric shock to the following circuits:

  • Power circuits for socket outlets (1, 2 & 3 Phase)
  • Lighting circuits
  • Directly connected handheld equipment
  • Directly connected stationary equipment within a high risk area.

All other final sub-circuits not in excess of 32 Amp are to be assessed RCD compatible and if so should be RCD protected to ensure they are both safe and compliant.

The purpose of the clause is to essentially minimise the risk of electric shock. When determining what an increased risk of electric shock is, we take into consideration the electrical equipment or appliance being used (e.g. is the electrical equipment Class 1, exposed conductive parts), external influences (e.g. exposure to elements, vibration, production line) and the connection to the supply.

There are exceptions however, one being applied where the equipment has leakage current that would impair on its reliable operation. This scenario would require a risk assessed appropriate alternative method of installation and equipment selection would be needed to achieve the same level as RCD protection; this could include additional mechanical protection, a separated supply or earth monitoring protection.

Even though the new standard calls for RCDs on all sub-circuits up to and including 32 Amp, exemptions can be applied for when:

  • Sub-circuits supply power to specialised equipment
  • Equipment develops a fault where a greater danger exists than leakage current
  • Equipment operating under normal conditions has the ability to produce earth leakage of a level that will trip a 30 Amp RCD
  • Single items of electrical equipment (e.g. a socket-outlet or light) which is not RCD-protected is replaced with an equivalent item in the same location – like for like
  • Reliability of the equipment is essential to the business operation.

The common complaint of nuisance tripping is not a valid reason for an exemption.

Comply with the Standards, it could save someone’s life, including yours.

What are the requirements for RCDs with alterations or replacement to switchboards?

RCD requirements are applicable when switchboards are altered or replaced. In an alteration, RCDs are required for final sub-circuits. RCDs are also required to protect power-outlets when added to an existing circuit (in accordance with the requirements for new sub-circuits, in the part of the installation in which they are located).

Where power-outlets are being added to an existing circuit and RCD protection is required, the RCD protection is only required to be fitted at the origin of the additional wiring. Where all circuit protection on a switchboard is replaced, additional protection by RCDs are required for the final sub-circuits supplied by that board.

As a Facility Manager, what do these changes mean for you?

The cost of installing new circuits for additional electrical equipment will be substantially higher, with the inclusion of RCDs. Be prepared for an increase in costs for additional circuits (especially 3 Phase), which may lead to the requirements for a switchboard upgrade, in order to facilitate the installation of the RCDs.

As commercial and industrial electrical contractors, it’s important that we are across all of the changes for our clients, awareness and safety are paramount.

Alex Lamblin – Director

 

For advice and assessment on your commercial and industrial electrical requirements call Prolux on 1800 800 880.

Improving Power Quality in Commercial Buildings

Posted on by Prolux

As a Facility Manager you’d be aware of the importance of using compliant electrical accessories and undertaking electrical testing to Australian Standards, but have you given much thought to the regulations surrounding Electromagnetic Compatibility (EMC) running throughout the commercial buildings you manage? NHP has and as a result they’ve released a compliant EMC Isolator for use with Variable Speed Drives (VSD’s) which successfully addresses EMC concerns.

Firstly let’s take a look at the issues surrounding EMC, and how you can identify them and effectively manage the problems.

What is Radio Frequency Interference and how does it affect EMC Compliance?

Have you ever had electronic equipment within close proximity to VSD’s that malfunction? If so, this is caused by Radio Frequency Interference (RFI), due to high frequency switching in the inverter of the VSD. This malfunction emphasises the importance of using screened cables (commonly referred to as VSD cables). What is not always understood is the importance of earthing the screen of the cable at the VSD and the motor end, in order to prevent RFI emissions. If an isolator is required on the output cable of the VSD, then a metal lined EMC Isolator with metal EMC cable glands must be used and adequately bonded to the screened VSD cable. This continuation of screening creates a ‘Faraday cage’ between the VSD and the motor, ensuring that no RFI is omitted from the circuit. The level of allowable RFI in a VSD circuit is outlined in AS 61800.3-2005. An EMC Isolator ensures consistent operation of industrial and electronic equipment, making it ideal for use where maintaining EMC Compliance throughout the installation is vital – particularly applications with motors controlled by VSDs, e.g. water pumps and air conditioning systems.

Achieve improved power quality with the ‘NHP Katko Series EMC Isolator’

Locally tested to comply with EN55011, the Katko EMC Isolator ensures safe operation in environments with electromagnetic disturbances, so you can ensure a high level of safety without compromise.

For added application flexibility, the compact unit has been specifically designed to occupy less space, ensuring easy installation and operation with a choice of larger enclosures for increased wiring space.

The key benefits include:

  • Electromagnetic Compatibility to EN55011 – safe within a sensitive environment
  • Pre-installed earth terminal – protects people and equipment from interference
  • EMC glands – suitable shielding of cable for electromagnetic purposes
  • Quality IP65/IP66 rating – ‘dust tight’ and protected against moisture (heavy seas or powerful jets) and heat
  • Copper coated enclosure lining.

How can you reduce Harmonics and enhance performance within power systems?

Another factor to consider in your building is reducing harmonics. Harmonic voltages and currents in an electric power system are a result of non-linear electric loads (e.g. office equipment such as computers and printers, fluorescent and LED lighting, battery chargers and also VSDs – equipment used to control the speed of machinery, as these can all play a part in power quality problems. As an example, if an internal power supply regulation is too noisy, that can adversely affect sensitive analogue measurements (for sensor products), or lower the performance of a radio transmitter (for wireless products).

Harmonics within power systems can also result in an increase in generating heat within the equipment and conductors, creating torque pulsations in motors (premature bearing failure) and misfiring within variable speed drives. Therefore, a reduction of harmonics is also considered highly desirable.

How are non-linear loads affecting Harmonics in buildings?

Years ago, non-linear loads were mainly found in heavy industrial applications, such as furnaces, heavy rectifiers for electrolytic refining, large VFDs, etc. The harmonics they generated were typically localised and often addressed by knowledgeable experts. However, times have changed, and today harmonic problems are common in not only industrial applications but in commercial buildings as well. This is primarily due to the new power conversion technologies, such as the Switch-Mode Power Supply (SMPS), which is found in practically every electronic device. The SMPS is an excellent power supply, but it’s also a highly non-linear load. Their proliferation has made them a substantial portion of the total load in most commercial buildings.

 

An LED light is one example of an electrical load with a non-linear characteristic, due to the rectifier circuit it uses (as shown in the above graph). The current waveform, blue, is highly distorted.

 

Prolux Electrical Contractors specialise in commercial and industrial electrical building maintenance and are proficient in replacing standard isolators with quality VSD EMC Isolators to maintain EMC Compliance.

Call us on 1800 800 880 to ensure your commercial building’s equipment is protected and running efficiently, whilst complying with regulatory standards.

I think I’ve tripped the safety switch, what do I do?

Posted on by Prolux

What is a safety switch?

Safety switches are devices connected to electrical cables within a home, factory or alike and they have the ability to detect the loss of a current from a particular circuit and cut off power to the affected electrical device in as little as 25 milliseconds. Safety switches are designed to save lives; they prevent electric shock and electrocution. They have become mandatory on power outlet circuits of new homes since 1992 and on light power circuits in most Australian states since 2000. Many older homes and business residences don’t have safety switches installed which means things like air-conditioning, hot water systems and kitchen stoves aren’t protected. As of 2008, all residential rental properties were required to have safety switches installed. Workplace supervisors have a responsibility to make sure that RCDs (residual current devices) are installed within their workplace and fitted to electrical circuits wherever hand-held electrical tools are to be used. RCDs are to be installed by a licensed electrician only.

Continue reading “I think I’ve tripped the safety switch, what do I do?” →

Safety Switches

Posted on by Prolux

Safety switches provide protection against injuries caused by electricity. Many of the fatalities caused by electricity could be easily prevented by installing a safety switch. A safety switch is designed to save lives by monitoring power flow and making sure it is even. When a person comes into direct contact with electricity, electricity is directed through their body to earth. This causes a loss in the amount of electricity in the electrical circuit (the path for the flow of electricity). A safety switch detects very small losses of electricity and immediately switches the power off within in a circuit in as little as 0.3 seconds.

Safety switches should be tested every three months to ensure they are in good working order.
You can test a safety switch by pressing the ‘Test’ or ‘T’ button. The safety switch should immediately trip to the ‘Off’ position. You will then need to return the switch to the ‘On’ position.

If your safety switch does not trip to the ‘off’ position after you have pressed the ‘Test’ button, cut the power immediately and call a qualified electrical contractor.

Electrical Safety Tips

Posted on by Prolux

The safety of your family is our primary concern.

To prevent future hazards and dangerous outcomes around your home, here are a few safety tips we recommend!

1. Grease and dirt can affect the functionally of appliances and can also make them unsafe. Cleaning your appliances regularly, by disconnecting the power and wiping down with a damp cloth, can improve the function of your appliance and prevent future hazards.

2. Safety switches are invaluable for protecting your family from serious injury, electric shock or even electrocution, along with protecting your appliances. Having an electrical safety switch installed is quite easy and relatively inexpensive, make sure you maintain your switchboard and if repairs or upgrades are required always use a licensed electrical contractor.

3. When changing a light bulb, ensure the electrical supply to the lighting circuit is turned off at the switchboard, and be sure to never replace light bulbs that exceed the socket rating.

4. Make sure you clean exhaust fans and lint filters in clothes dryers regularly to prevent risk of fire and damage to appliance.

5. It’s very important to always have a functional smoke detector. Maintain your smoke detectors by ensuring that you have changed the battery at least once a year, cleaned/dusted the detector and tested the detector at least once a month to ensure your family’s safety.