2.2 Safety switches
2.2.1 Does your work area have a safety switch or switches?
2.2.2 How to find out which equipment is protected by a safety switch
2.2.3 How do you test your safety switch and how often should you test it?
2.2.4 How do you ensure that your electrical installation remains electrically safe?
Safety switches are devices that cut off the electricity supply when there is a very small earth fault on an electrical circuit. Since earth faults are the most common type of fault involved in electric shocks, safety switches are a good way of reducing the risk of death or injury from electric shock. Safety switches have other advantages, for example, they detect an earth fault long before a normal fuse or circuit breaker will detect the same fault, and this can sometimes save the equipment from more serious damage.
2.2.1 Does your work area have a safety switch or switches?
Safety switches are generally located on the switchboard of an electrical installation, although they can be located elsewhere. The most common other location for an installed safety switch is at a power point which has the device built in to it. There are portable safety switches which will provide protection for plug-in electrical equipment.
Figure 11 below gives a representation of where safety switches are located in a typical rural industry installation. This installation has three switchboards. In this installation the switchboards have safety switches to protect power points and other electrical equipment. However, it is important to note that the switchboards themselves are not usually safety switch protected.
Fig. 11
Figures 12 shows three common types of switchboard mounted safety switches, mounted together.
Fig. 12
A typical safety switch incorporated in a power point is pictured at figure 13.
Fig. 13
Figure 14 below shows three different types of portable safety switch. You can use portable safety switches as described in section 2.1 to meet the regulatory requirement where there are stated electrical risk factors.
Fig. 14
Your electrical installation will have at least one switchboard. It may have more than one. Very large installations can have many switchboards located throughout the building or buildings, and there may be switchboards located out of doors and not attached to a building. You should check all switchboards and power points to determine whether safety switches are fitted.
The devices you will find on switchboards can include:
- fuses;
- circuit breakers;
- safety switches;
- combination devices that are both a circuit breaker and a safety switch.
Not all of these devices will be on every switchboard. Sometimes a switchboard may consist only of a number of circuit breakers or a number of fuses. Some switchboards will have a device of all the types mentioned above, and may have other electrical devices, including power points.
The purpose of fuses and circuit breakers is to protect circuit wiring from damage in the event of a fault, and to prevent exposed conductive parts of electrical equipment from becoming live long enough, or to a high enough voltage, to cause a person a serious shock in the event of an electrical fault.
Safety switches often look similar to ordinary circuit breakers. The main external feature that a safety switch has and most circuit breakers do not is a test button (larger circuit breakers of 150 amp capacity or more can have test buttons).
2.2.2 How to find out which equipment is protected by a safety switch
Ideally, each safety switch should have marked on or beside it the circuits or equipment it protects. Often however, the marking will not be specific enough to identify every item of equipment protected.
To identify the electrical equipment protected by a safety switch, carry out the following procedure:
- Turn the safety switch off—you can do this by pressing the test button or by operating the on/off toggle or switch.
Please note: If pressing the test button does not cause the switch to flick to the off position, the safety switch is faulty and requires checking or replacement by a licensed electrical person.
- Check which equipment or circuits are not functioning, by:
- turning on lights;
- turning on fixed equipment using safe procedures; or
- checking power points using a convenient appliance such as a radio.
- List items not functioning.
- Turn the safety switch back on.
- Check that listed items now function.
Listed items which function after the safety switch is turned on are protected by the safety switch. Items which continue to function when the safety switch is turned off are not protected by that safety switch.
This procedure needs to be conducted for each safety switch, and will result in a list of all safety switch protected equipment. All other equipment will not be safety switch protected.
If you have a safety switch that is a portable type, you should ensure it is tested before every use.
2.2.3 How do you test your safety switch and how often should you test it?
You can test that your safety switch is operating correctly by pushing the 'test' button on the unit. The safety switch will automatically trip 'off', confirming it is operating correctly. If the safety switch does not operate, you must have the unit checked or replaced by a licensed electrical person as soon as possible, and you should prevent others from using equipment that would otherwise be protected by it, by leaving it turned off, unplugging handheld items and affixing a warning tag.
There is no prescribed time limit for testing of your safety switch, but it is recommended that you test it in accordance with the manufacturer's instructions. Where manufacturer's instructions are not available, you should test the safety switch every three months.
2.2.4 How do you ensure that your electrical installation remains electrically safe?
You have an obligation to ensure that all electrical equipment used in your rural industry business is electrically safe. A way of achieving this is to have an electrical contractor inspect the electrical equipment regularly or when you have them attending for other maintenance or repair work. An electrical contractor inspection at least every ten years could assist in ensuring a safe installation.
Last updated July 16, 2009
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