The safe use of generator equipment:
End-users who use power generators to interface with fixed electrical installations must adhere to the regulations of the OHS Act and SANS 10142-1.
Many end-users cause illegal electrical installations when they resort to alternative power supplies during utility outages. SANS 10142-1 clause 7:12 prescribes the minimum safety requirements for the use of alternative power sources. This standard makes it very clear that alternative supplies include but are not limited to LV generating sets and photovoltaic (PV) installations.
The requirements are of a very technical nature and must be clearly understood and applied. All electrical installations must also comply with the Electrical Installation Regulations. Failure to comply with the regulations and standards may lead to prosecution or invalidate insurance claims and warantees.
Note: Remember that a generator installation must be executed by a person registered with the DoL. The registered person must issue a CoC upon completion of the electrical installation.
Safe work practices
- Maintain and operate the generator in accordance with the manufacturer’s operating manual.
- Never connect a portable generator or any other alternative supply (hydro or wind generators, photovoltaic systems etc.) directly to an existing electrical system unless the alternative supply has its own automatic or manual changeover switch.
- Connecting any unauthorised power source directly into any point of electrical wiring without a changeover switch is illegal and dangerous because of so-called “back feeding” which, by definition, means supplying power back into the grid when the grid is down. This must be avoided at all cost as the voltage fed back into the lines poses an electrocution hazard for utility workers and others who may not know that the line is charged.
Connection of any alternative power supply must comply with SANS 10142-1 Annexure S Emergency power installation configuration.
- Never use a plug-to-plug cable to connect the generator to a socket outlet. Many generators are supplied with plug-to-plug cables but their use is strictly forbidden as it provides no earth leakage protection.
Should the utility power be restored while the main circuit breaker is not switched off, the generator may be damaged or the entire system may be burnt, causing fire hazard.
While the main supply is not available, the generator will send power back into the main cable. This may overload the generator and shock electricians working on repairs on other power lines.
- Always use the portable generator in a well-ventilated area due to the threat of carbon monoxide (CO) poisoning from the engine exhaust. Generators should never be run in garages, under carports or near open windows. A typical 5,5 kW home generator can produce as much CO as do six idling cars.
- Always refuel the generator when it is not running and never store the fuel near the generator.
- Use a registered person in accordance with the Electrical Machinery Regulations to do the electrical installation. The registered person can be an installation electrician (IE) or master installation electrician (MIE) registered as a contractor with the Department of Labour. The registered person must issue a Certificate of Compliance upon completion of the installation.
- Always ensure that the generator is started first and that the power is switched on while the generator is running.
7.12.2 Requirements for alternative sources of supply
126.96.36.199 Where any form of alternative supply (emergency supply, UPS etc.), is connected to an electrical installation, a notice to this effect shall be displayed at the main switch of the installation, and where such supply
a) supplies power only to certain circuits in a distribution board, a power-on indicator (visible or audible) shall be provided on each such distribution board as well as a notice indicating that the standby power main switch shall also be switched off in an emergency,
b) only supplies a part of the electrical installation, the notice shall also be displayed on each distribution board in that part of the installation (see 188.8.131.52(d)).
184.108.40.206 The means of excitation and commutation shall be appropriate for the intended use of the generating set and the safety and proper functioning of other sources of supply shall not be impaired by the generating plant.
220.127.116.11 The prospective short-circuit current and prospective earth fault current shall be assessed for each source of supply or combination of sources, which can operate independently of other sources or combinations. The short-circuit rating of protective devices within the installation and, where appropriate, connected to the main supply, shall not be exceeded for any of the intended methods of operation of the sources.
18.104.22.168 Where the alternative supply is intended to provide a supply to an installation that is not connected to the main supply, or to provide a supply as a switched alternative to the main supply, the capacity and operating characteristics of the alternative supply shall be such that danger or damage to equipment does not arise after the connection or disconnection of any intended load as a result of the deviation of the voltage or frequency from the standard range. Means shall be provided to automatically disconnect such parts of the installation, as may be necessary if the capacity of the alternative supply is exceeded.
22.214.171.124 Where an alternative supply is provided to an installation or part of an installation as a switched alternative to the main supply, the change-over switching device shall disconnect the main supply before the alternative supply is switched in. The change-over switching device shall be interlocked in such a way that the main supply and the alternative supply cannot be connected to the installation or part of the installation at the same time.
126.96.36.199 Except where otherwise permitted in this part of SANS 10142, where a socket-outlet is installed in a circuit on standby power, such circuit shall be protected by an earth leakage protection device with a rated earth leakage tripping current (rated residual current) I∆n not exceeding 30 mA.
188.8.131.52 A 230 V generator with a V-O-V earth connection (centre tap on winding which is earthed), shall not be connected to a fixed electrical installation.
Note: Such a generator may be used as a free-standing unit to provide power to specific appliances.