Using a power generator at home

  • Posted: Jun 23, 2008
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Using a power generator at home

Generators that are used to supply a portion of electricity, when the main electricity supply fails, is usually either petrol or diesel driven.

The engine of a generator needs to be started just as the engine in the car and some engines are started by the manual pulling of a rope attached to the engine similar to the type used to start the engine of a lawn mower. Other more complex generators have a battery with a starter motor and a switch or push button to start the engine, and the even more advanced generators are started automatically when the supply from ESKOM fails. Most of the largergenerators are started this way and are be used in hospitals, and other critical applications.

The generator will start generating power once the engine starts, which will eventually stabilise at around 220 volts until a load or wattage is connected. This is where it is important to decide what load will be connected to thegenerator. The greater the load the bigger the generator needs to be and therefore the greater the expense.

Choosing a generator
Before you choose a suitable generator for your home it is important to decide what you intend using the generatorto supply. You will need to decide what equipment e.g. appliances or lights will be required to be operational during the time the generator is in operation; this will determine the size and the cost. Get the right advice before deciding which one suits your application as you should never exceed the manufacturer’s specifications.

Remember all the heating appliances will draw the most power, i.e. the stove, geyser, dishwasher, washing machine, tumble dryer, toaster, kettle, hairdryer etc. Control the number of lights you use. Computers and electronic equipment consume little power, but if the generator does not deliver a constant voltage and there are dips and spikes in the system, electronic equipment is likely to suffer damage. Most modern fridges are electronically controlled, and a fridge is likely to be high on the list of essential items. Depending on the time the generator is in operation it will be helpful to put into effect some of your internal load shedding. Switch off some lights to allow you to boil a kettle etc.

The transfer or change over switch
The connections between the municipal or Eskom supply and the generator supply are a vital part of the overall safety of the installation. It is a requirement that the installer must ascertain the requirements of the supplier prior to connecting the generator.

The transfer or change over switch in a domestic installation is likely to be a manual device which has three switching positions. These may vary depending on the switch, but most have a central off position and a position to the left and right of the off position. One is for the Main Supply and the other for the generator supply. This will mean that when the main supply fails the switch will have to be manually turned from main to the generator supply. The whole process will have to be repeated once the main supply returns. These transfer switches can also be automatically controlled, but this system is far more complicated and costs a great deal more.

The main supply and the generator supply must never run in parallel. The licensed electrician, who must carry out the installation, will understand the requirements for the wiring of these switches, as incorrect wiring of all the live, neutral and earth wires could be extremely dangerous.

Installation and connection of a generator by a qualified person
Remember that this work must to be done by a registered electrical contractor who knows what he is doing. You can check whether your contractor is registered by contacting the local offices of the Electrical Contracting Board of South Africa, which are situated in each province in South Africa. In addition always make sure that he issues you with a valid Electrical Certificate of Compliance. NEVER attempt this work yourself. Remember that a Generator is in itself a Supply Authority and the dangers and risk of electrocution are exactly the same.

Generators and the law
The South African National Standard (SANS 10142-1:2003) for the Wiring of Premises Clause 7:12 prescribes the minimum safety requirements for the installation of low-voltage generating sets. These are legal requirements, and failure to comply with these requirements could invalidate any home owners insurance should it be established that a fire or injury was caused as a result of the in correct connection to a generator. The requirements contained in the Standard are of a very technical nature, and must be clearly understood and applied.

Regular testing
Generators must be tested at regular intervals, and the tests must be carried out as if the generators were in operation.

The position of the generator

The battery
If the generator has an automatic start facility care needs to be taken of the battery. Just as a car battery needs care and maintenance.

Noise factor
Generators are noisy and therefore need to be positioned in a place where the noise will not intrude in the house or disturb your neighbours.

Heat factor
Generators will get hot, so care needs to be taken that no one will get burnt by coming into contact with the hot exhaust pipe.

Exhaust gas
The exhaust gas needs to be dissipated into the open air, and care needs to be taken that the generators will not emit exhaust gas into a poorly ventilated room and thereby cause carbon monoxide poisoning.

Fuel storage
No amount of sophistication of your generator will be of any use without fuel. Power outages occur when we least expect them. Accordingly, fuel needs to be permanently available and stored in a suitable container, in a suitably ventilated room. Remember that your local petrol station may also be without power

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