In this article I'll examine a few common electrical items around the home and discuss how safe they are.
This has been recognised as a hazard for many years, and yet is still available.
The hazard associated with these devices is that of fire. In the past, when wall sockets were few and the adaptors unfused, the problem was seen as overloading, in that it was possible to draw more than the rated 13A.
Today, overloading is a lesser problem as they are now fused (although many older, unfused ones are still in use). The greater problem is now the weight of the plugs, especialy as many appliances now come with plugtop power supplies. Most wall sockets are at low level and are hidden by furniture. Over time, the weight of the plugs can cause the adaptor to come away from the socket and eventually cause arcing and heat. As this can hidden by funiture, the problem goes unnoticed.
It is interesting to note that the warnings about these devices are still about overloading. But the advice is to replace them with bar type adaptors.
As copper is a good conductor of heat as well as electricity, it is possible for a fire to start well away from the initial fault.
After the advice to use bar adaptors instead of block adaptors, are these also unsafe?
They are not unsafe, but should be used with caution.
The important term is "domestic". These sockets are designed for light duty use and, as can be seen in the photograph, are constructed using folded contacts in a plastic holder.
In normal use, appliances will be plugged in and rarely unplugged, eg. TV, DVD, satelite, etc. In this context, they are being used as designed, and are safe. The problem arises when appliances are frequently plugged and unplugged (eg. vacuum cleaner) and, over time, this can cause the contacts to open and again create a fire hazard through poor contacts and arching.
Compare the above photograph with this photograph which shows the construction of an industrial grade socket of the type used for wall outlets.
It is always better to have extra sockets properly installed to the correct standard in the home / workshop / shack rather than use extensions and adaptors.
Sold as a means of protecting children, there is a campain against these items which, it claims, can be more hazard than help, see: www.fatallyflawed.org.uk for eye-opening information on this.
The British 13A plug and socket is one of (if not the) safest general mains connector in the world. Constructed to BS1363, it dates back to 1947. The standard has always specified the socket as having an integral safety shutter to prevent anything other than a correctly inserted plug from contacting the live and neutral conductors.
Unlike the plugs themselves, these "safety" covers are not regulated, and many are so poorly designed that even when inserted correctly they will actually allow small objects, such as needles and paper clips, to be inserted and contact the live conductor.
Most BS1363 sockets use a simple shutter mechanism that is operated when the longer earth pin is inserted. As the safety covers are made of a thin plastic, if they are inserted upside-down then they can easily bend or break leaving the shutter open and the live contacts fully exposed.
This photograph shows an alternative shutter method. Made and patented by MK, this shutter can only be released when the live and neutral pins are inserted simultaneously. While this stops the problem of a mis-inserted cover, it does not stop the access when one is inserted correctly.
One of the claims of these "safety" covers is that they prevent children from pluging in appliances such as heaters. Surely the easiest way of doing that is to remove the appliance from where the children are?
The object of this article is to inform and not alarm. In the case of the plug adaptors, both types comply with BS1363 and are legal for sale and use in the U.K. Knowing the shortcomings of each type allows you to choose how and where to use them safely.