ELECTRICAL HAZARDS

Injury to persons
There are numerous ways in which personal injury may be caused, two common electrical induced injury are:

1. Shock
Electric shock is the effect produced on the body, particularly the nervous system, by an electrical current passing through it. Its effects depend on the current strength which in turn depends on the voltage, the path the current takes through the body, the surface resistance of the skin (much reduced when wet) and several other factors. A voltage as low as 15 V can produce discernible shock effects and 70 V has been known to cause death. Generally speaking fatalities occur from the use of normal domestic and industrial voltages of 230 V a.c. and above, causing currents of greater than 30 milliamps to flow through the body for longer than 40 milliseconds.

The most common cause of death from shock is suffocation and accordingly, it is highly desirable that those dealing with electricity should be trained in resuscitation. Minor shocks in themselves may not be serious but they can lead to serious consequences; for example, the associated muscle contraction may lead to falls from working platforms or ladders.

2. Burns
These are caused by the passage of heavy current through the body or by direct contact with an electrically heated surface. They may also be caused by the intense heat generated by arcing from a short circuit. Electrical burns are a very unpleasant form of burn and require immediate medical attention.

Tech Couriers are required to understand the risks associated with dealing with electricity when on call outs for installations, repairs and decommissioning equipment.

Appliance Power Rating

The appliance power ratings shown in the table represents at an example noted from a random selection of devices available in the retail outs, offices and homes.

Electrical power is measured in watts, W, a unit of power. Electrical current is measured in amps, A, the rate at which electricity flows.

Domestic Portable Appliance	Amps Used	Watts Used
Laptop	<0.5	65 - 100
Mobile phone charger	<0.5	<12
Kettle	13	3000
Satellite TV box	<0.5	30
Printer	<0.5	50
Radio	<0.5	40
Radiator	8.5	2000
DVD player	<0.5	28
Hair dryer	10.0	2200
Landline cordless telephone charger	<0.5	10
Computer monitor	<0.5	100
Desktop computer	3.0	700
Television 42" HD	0.5	120
Games console	0.86	<200
Washing machine	10	2200
Toaster	9.0	2000
Tumble dryer	11.0	2500
Dishwasher	10.0	2200
Iron	12.5	2800
Microwave	4.5w	1000
Vacuum cleaner	9.0	2000
Radiator (oil filled)	13.0	3000

- The fuse in a plug is a safety device designed to protect the lead rather than the appliance. It is a deliberate weak link in a circuit which will 'blow' if an electrical appliance or extension lead draws too much current due to either an overload or a fault. The blown fuse cuts off the electricity to stop the lead and appliance from overheating and causing a fire.

- Appliances meeting the relevant product safety standards will always be fitted with a plug having a correctly-rated fuse. If you have to replace a fuse, it's essential, having checked and corrected the reason for the fuse blowing, to replace it only with another of the same rating.

- As a rule of thumb, fuses are rated according to the power rating of the appliance. Plugs for appliances rated up to about 700 watts should have a 3 amp fuse (coloured red).  Plugs for appliances rated between about 700 watts and 3000 watts (the maximum rating of a wall socket) should be fitted with a 13 amp fuse (coloured brown). (Some older appliances were fitted with 5 amp fuses (coloured black), which are still available to buy.)

Overloading Socket

Avoid overloading sockets and risk of fire by following this simple advice:

•Check the current rating of the extension lead before plugging appliances into it. Most are rated at 13 A, but some are rated at only 10 A or less - the rating should be clearly marked on the back or underside of the extension lead. If not, refer to the manufacturer’s instructions.

•Never overload an extension lead by plugging in appliances that together will exceed the maximum current rating stated for the extension lead. This could cause the plug in the wall socket to overheat and possibly cause a fire.

•Use our overload calculator (below) to check if you’re exceeding the maximum load.

•For an indication only of the current ratings of commonly-used domestic appliances - check out our information about Amps and Watts above.

•Only use one socket extension lead per socket and never plug an extension lead into another extension lead.

•Use a multi-way bar extension lead rather than a block adaptor, as this will put less strain on the wall socket. Some block adaptors do not have a fuse, which increases the risk of overloading and fire.

•Consider having additional sockets installed if you regularly rely on extension leads and adaptors - and use a registered electrician to carry out the installation work.

•Check regularly for the following danger signs:
 - a smell of hot plastic or burning near an appliance or socket
 - sparks or smoke coming from a plug or appliance
 - blackness or scorch marks around a socket or plug, or on an appliance
 - damaged or frayed leads
 - coloured wire inside leads showing at the plug or anywhere else
 - melted plastic on appliance casings or leads
 - fuses that blow or circuit-breakers that operate for no obvious reason

HAVE A GO AT THIS SOCKET OVERLOAD TEST

An easy to follow and useful website for couriers to checkout to gauge socket overloading
http://www.twothirtyvolts.org.uk/socket-overload/