Some properties in the UK use an earthing system where the earth conductor is bonded to the neutral at the supply station, and not bonded to an earth electrode at the property. This system is called Protective Multiple Earthing or PME. Under certain fault conditions a high potential may exist between the mains earth of a PME supplied property and any earth electrode fitted at that property. Because of the safety risks associated with such a fault condition, properties using the PME system MUST NOT install supplementary earth electrodes at the properties. Before installing any supplementary RF earth, you should check that your property is not connected to a PME type supply. Your electricity supplier should be able to provide you with this information. If you are in any doubt, consult a qualified electrician. Remember electricity kills!
Amateur radio is a hobby which involves a great many wires and cables. As your hobby grows, the number of cables associated with it will also grow. This is unavoidable as we add more antennas for more bands, experimental hook-ups and the like. All these cables entering one small space present a significant risk to personal safety and well-being. Think about the number of different injuries that can result from tripping over a cable when you add the presence of sharp metal edges, high voltages and heavy pieces of equipment. As well as impact injuries from falling and from pieces of equipment being caused to fall onto you, there is also the danger of falling equipment breaking open exposing potentially dangerous live parts.
Route your cables carefully, keeping power, PF and data cables separate where possible (for EMC reasons). You may like to consider installing conduit trunking to contain some of the more permanent cabling such as your main antenna feeders. There is a type of conduit trunking available from several manufacturers with slotted sides making it very east to route cables in and out where required. On no account should cables be left trailing over the floor or run loose under doors or carpets. Such an arrangement will cause the insulation to fray over time risking electric shock or fire.
Obviously tools such as knives and soldering irons carry obvious risks, but while many appreciate the burns risk from soldering, it is less obvious that there is a danger of splattering hot solder up into the face and eyes, particularly when soldering multi-cored wires that may spring back slightly when the iron is removed. For this reason goggles should be worn when soldering.
Car batteries are a temptingly cheap form of high current 12V power supply, but they really have no place in the domestic environment. They are very heavy, contain highly corrosive sulphuric aid and give off explosive gases when charging. If you want to use batteries, use sealed lead-acid batteries (SLA), but remember that these require a special charger, a car battery charger is not suitable.
If you use headphones remember that while they may assist in making out a weak station, they can potentially cause serious permanent hearing damage if turned up too loud. Don't be tempted to use an excessive volume in an attempt to resolve a station who is "almost readable". Also remember that the wearing of headphones can make you oblivious to your surroundings so always remove them before moving from your operating position - also advisable if you don't want your lovely new rig following you across the floor!