The two most common sources of electricity for power tools are mains electricity and rechargeable battery.

Note that heavy industrial machines generally run on 415 volt power, also called 'three-phase' power.

However, they use a different type of power plug and socket and are not produced in the hand-held range of power tools.

Mains electricity

Some people refer to mains electricity as '240 volt power', because that's the voltage that comes out of a standard power point.

Standard power points are designed to take two-pin or three-pin plugs. One pin connects to the active or live wire. The opposing pin connects to the neutral wire, which completes the circuit.

The bottom pin has no role in delivering electricity, but connects the tool to the earth wire as a safety mechanism, in case there is a malfunction or 'short circuit'.

Power circuits are always protected either by a fuse or circuit breaker.

If the system is overloaded or a fault develops, the fuse is designed to blow, or the circuit breaker to trip, which cuts off the power supply.

There are two main systems of insulation used in power tools:

• Single insulated tools use an earth wire which is connected to the metal casing of the tool at one end and the earth pin of the plug at the other end.
  
  In the event of a fault that causes a short circuit, the current is able to flow straight to earth without giving the operator an electric shock.

• Double insulated tools use two layers of insulation between the internal parts that carry a current and the outer metal parts of the body.
  
  For this reason, they are not connected to an earth wire.

Rechargeable battery

As rechargeable batteries continue to improve in performance and power output, an increasing variety of 'cordless' tools are coming onto the market, including jigsaws, circular saws, planers, and even chainsaws.

However, by far the most common cordless power tool is the drill.

This is because most drills are smaller and consume less power than the other types of tools, so their rechargeable batteries are lightweight and relatively cheap.

Always remember to pack the battery charger when you take cordless tools to the jobsite.

It's also a good idea to take two batteries, so you can leave one on 'charge' while the other is in the tool.

Safety with mains power

Mains power is used everywhere, but that doesn't mean you should take its safety for granted.

Every year people are hospitalised as a result of electric shock, and occasionally the shocks prove fatal.

Electrical faults are also responsible for many fires, because the sparks from short circuits or the heat from overloaded wires can ignite flammable substances or materials.

The first rule when using power tools is to make sure the electrical cable is in good condition.

Check that the insulation is sound and there are no exposed wires at the plug end or the other end where it enters the tool.

The second rule is to avoid using electrical tools in wet conditions. If it has been raining, or you're in a wet area, only use the tool if:

• your hands are dry
  
  
• the tool is completely dry
  
  
• you are wearing rubber soled boots and standing on a dry surface
  
  
• electrical leads and connections are clear of damp ground.

Testing and tagging

It is a WorkCover requirement that all power tools used at work are tested and tagged every three months by an authorised person.

The test is designed to ensure that the tools are safe and not likely to cause a fire or electric shock.

Once a piece of equipment has been tested and passed, the authorised person attaches a tag to it, stating their name or company they work for and the test date.

If you pick up a power tool and find that the tag is out of date, make sure you take it straight to the person responsible for getting it tested.

Setting up extension leads

If the power source is not close to the area you're working in, you may need to run an extension lead some distance.

Always make the effort to keep extension leads safe, because they can be a serious hazard to your own team as well as other workers on-site if you don't.

Click on the link below to see some tips on how to use extension leads safely.

Tips on using extension leads at jobsites