Few of us would relish the prospect of life without electricity. It is central to the way in which our homes are run and our lives are enjoyed. Yet, as soon as that electrical supply enters our properties it creates, for each and every one of us, a very real hazard. Should the supply be mismanaged or otherwise flow through degraded electrical wiring or into faulty electrical installations and equipment, we become exposed to the risk of electrical shocks, which could be fatal.
Electric shocks
An electric shock happens when a person is exposed to a live electrical conductor, and that person is in contact with a surface or material of different voltage potential - such as the ground beneath their feet. Electricity always seeks the path of least resistance towards earth, so it can discharge. If you happen to be that path, your body will end up connecting the current from electricity supply to earth. The cut a long story short - it only takes a few seconds - there is a real danger of the person to be continously charged for a couple of seconds, by the time realisation hits it might חס וחלילה be too late. In the home the main danger from electrical shock is, of course, to be working directly on (or with) faulty electrical wiring and equipment. But even if this is not the case, you can still receive a lethal electrical shock by touching materials of high conductivity that have become 'live' in your property, such as metal pipes. It is for this reason that all metal pipes in the home should be cross bonded and earthed.
As of today, there are many houses whose wires were laid in the 1920's and have never been replaced, adapted or even checked. Any competent Electrical Contractor will then advise the owner to promptly replace the aged circuits with an up to date installation.
Cross bonding
Cross bonding is the term used for earthing all fixed metal items in a property, and bonding them together to the earth connection terminal at the consumer unit / fuse box or to a local earth. Once earthed, should these items become live through faulty electrical works, the current will be 'made safe' by the earth connection, so greatly reducing the chances of an electric shock to anyone who touches them. Items to be earthed in the home include metal service pipes (gas and water), radiator pipes and metal pipes for sinks / basins, baths, towel rails, shower units and similar.
The process of cross bonding is, in principal, quite straightforward. All it requires is that an earth connection (yellow/green sleeved earth wire) be attached to the metal pipes by way of an earth clamp or earthing tag. The earth can then be run to other metal objects and attached similarly. Alternatively, each item can be earthed using a separate wire. The earth wires can then be earthed individually or 'grouped' before being earthed at a common point.
In practice it is strongly recommended that only a qualified person undertake the cross bonding process. If a clean earth connection is not made, any number of fixed metal objects in the home could still present a danger if they were to become live. Additional regulations also apply in kitchens and bathrooms, as per the IEE Wiring Regulations.
Cross bonding and the law
At the time of writing there is no legal requirement to cross bond metal items in the home. It is however highly recommended that you do so for your own safety - and if you are a landlord, for the safety of your tenants. Gas safety and electrical safety inspections are a good way to find out if your cross bonding is sufficient or not. Should cross bonding, in the opinion of the inspector, be insufficient, they have a duty to notify you. It is then up to you to take action and make your property a safer place to live in.
No comments:
Post a Comment