# UK Amateur Radio ## Foundation Licence 2002
## SAFETY
### Sources of danger: Mains, Power supplies and High current batteries. The whole idea behind the Foundation Licence Course is the avoidance of risk of electrical shock and therefore the skills required to open up a piece of live equipment is considered outside the scope of the course. There are however, still many dangers in a shack (the operating room) which need to be considered. ### HIGH VOLTAGE In my opinion anything above 12 volts is considered high voltage. Thus mains voltage (240V AC) that is used in the home (UK) plug sockets and the light fittings is a high voltage and also brings the possibility of DEATH. Never open up a piece of equipment as you may not know what to do when you have and in any case you could do far more damage dropping a screw driver inside the open case than any good you might in locating a detached wire. If you see a warning on a piece of electrical equipment that mains voltages exists inside then I consider that repairs MUST be left to a qualified electrician. ### HIGH CURRENT High capacity batteries such as car batteries, sealed lead acid, nicads and NimH types, although low voltage are able to deliver high currents if short circuited. Thus power battery source even at 12 volts has its dangers and the same can be said for a power supply operated with an output of 12 volts and driven from the mains supply. If the terminal of the battery or the power supply were for instance shorted out by a wrist watch, finger rings, or even a piece of wire serious burns could result from the heat generate when the metal conducts the high current even thought it is low voltage. #### If fact the heating effect can be so great that is can cause a fire, vaporise metal watch straps, and screwdrivers with a potentially blinding flash and shower of molten metal.
### Mains Plug and Earths Let us assume that we are dealing we a piece of equipment which has it own power supply inside the case and a wire from the mains supply voltage has dropped off and is touching the case. What might be the result if we touch the case. Think about what was said in the previous section. The answer is there may be a danger of death. Why? Because unless the case is properly connected to earth as it should be ,the fuse in the plug will not blow and even if the fuse did blow it might be too slowly to protect you or me from the danger of high voltage. So how could we check if the case is properly connected to the earth. If you have a test meter handy set it to the buzzer position (assuming it has one) when the probes are touched together. Now find the plug and locate the earth pin. You don't know which is the earth pin...... Right we must stop here and discuss the plug. Click here So we start again here just below where we left off. Check that the buzzer works by touching the two probes together. Now make one probe touch the Earth terminal of the plug and then find a spot on the case where there is a screw fixing or some paint missing. If the buzzer sounds then we know the case of the equipment is safely connected to earth. No buzzer then the case may not be connected to earth or it might even be a plastic case and further investigation outside the scope of this course is required. #### Should you ever decide to take a look inside a piece of equipment make sure it is disconnected from the mains or the power supply. Merely turning off the switch is not enough, it must be fully disconnected by pulling out the plug from the mains supply or disconnecting the leads from the power supply. KEEP SAFE ALL THE TIME. DEATH IS PERMANENT!!!
| Here I am working safely on a piece of radio equipment, there is no clutter!!!
### The 13 amps fused plug All the plugs in your house should be of this type else they are very old and the house need to be rewired !!! However the term 13 amp plug means all plugs but they have a fuse in them that can be up to 13 amps and a little as 2 amps. It is necessary to put the smallest value fuse in the plug that will allow the equipment to which it is attached to work properly. The purpose of the fuse is to protect the internal parts of the equipment and the cable connecting the equipment to the plug should a fault occur. Low power equipment will have thinner cable than high power equipment so if the wrong fuse is in the plug and a fault occurs in the equipment the cable could over heat and cause a fire. If too small a fuse is used then it will also blow but not because of a fault in the equipment just because the equipment needs more current than the fuse will allow. So which pin is which? The photo shows you the top off a plug. Note which colour cable is going to which pin connector. The EARTH pin is the one that stands on its own at the top of the plug and is connected to the GREEN and YELLOW cable. The Live or Positive wire is coloured Brown The Neutral wire is coloured Blue. | Looking down on the inside of a plug which has had its top taken off. It is very important that you fully understand how to wire a plug. You must also know:- 1. that there must not be any whiskers of wire that could touch the wrong connector. 2. that the cable clamp must be properly fastened to resist the cable being pulled out of the clamp. 3.be able to identify a faulty or otherwise incorrect plugs
Now have a look at the picture of the under side of the plug and think carefully about which colour wire is connected to the pins. |
This photo indicates which colour wire goes to which pin. |
This photo identifies what the screws do. |
Make sure you are absolutely certain that you know all about the plug, its wiring and fuse capabilities. It could mean life or death.
### ### Protective Multiple Earthing (PME) If an RF earth is used it must be connected to the (PME) earth bonding point at the consumer unit, using a conductor of at least 10mm2. Amateurs should also be aware that external parts of the station, such as antennas and their associated metalwork, under rare fault conditions, such as a rupture of the neutral conductor on the supply company's system, a higher potential difference may appear which could, in theory, rise to phase-to-neutral voltage (240V). As with any aspect of electricity supply, anyone who does not have the necessary knowledge should take advice from a qualified electrician or consult their Regional Electricity Company (REC).
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### Actions to be taken and avoided in the event of an accident You must know that an accident involving electricity the first action that must be taken is to switch off the power supply at the mains or the isolating switch in the shack. You must not touch the person who has had the accident until you know the main power is off, as until then there is the risk that the injured person is still connected to the mains and you too could end up electrocuted!!! ### Single isolation switch The radio shack should therefore be designed with a single isolation switch which is easily identified and accessible, that when turned off shuts down all the power supplied to the shack. It is assumed that the principal electric lighting in the shack is on a separate supply circuit and will remain live when the other switch is turned off so that you can still see the situation. FIRST turn the Mains Power OFF then attend to the injured
### Station layout and tidiness What a terrible mess we can see in the pictures below!!!!
### Dangers inside the shack The two pictures above show an absolute shambles of untidy mains cables which can be a trip hazard when they are across the floor. There is also the possibility that the cables will fray or be pulled out of the plug cable restraint which could result in electrocution or fire. Equipment could also be dragged off the bench, which if live, could cause fatal injury or expose live wires. The picture on the right above is not much better. At least the coloured cables are all low voltage but the rig is cluttered by them. The other cables are associated with the aerial and are also very untidy. Here is a nice tidy shack - note the Transceiver is readily to hand and the log book and pen ready to note the contacts. The picture on the right above is of Amateur TV. It may inspire you to one of the different modes other than voice communication. ### Dangers outside the shack Outside of the shack there are just as many if not more dangers. All wires that are off the ground must be safely secured so that they cannot fall onto anyone or be fouled by ladders of the local window cleaner. Thus cable must not be allowed to pass across an opening unless very high up or at ground level. Such cables at a safe height need to be properly fixed to withstand wind and bird strike. Here the cables are neatly tucked under the gutter which also gives some protection from the rain but more importantly they are held above the door frame which is in the bottom of the picture.
But even here there can be a problem with locating cables high up or even for that matter aerials as they must not be located anywhere near to overhead power cables. There are Codes of Practice for installation of such overhead cables where power is concerned but domestic aerial cables may well not meet these requirements. Putting up aerials can be a potentially dangerous activity. The mast even if it is a light timber one - when the aerials are on top it will be much heavier and therefore more difficult to control especially in windy conditions. Working on a ladder even a short one can be dangerous!!! One false step and you could fall off the ladder and you and the aerial and mast come crashing down to the ground. If putting up an aerial requires access to a roof then ensure that such work is not undertaken on your own. A fall from a roof top has been know to kill a well know celebrity whilst he was trying to get a better picture. Assuming that you are a young person ensure that you get the help of a suitable adult to help you put the aerials up. It might seem a silly comment, but do not touch the main station aerial component parts whilst the transmitter is being used. The aerial must be located so that it cannot be accidentally touched from ground level. Burns from RF power from a transmitter can occur from arcing or energy absorption into body tissue. RF burns can even be received when the antenna wires are insulated. Also consider your pets and wild animals. If they come into contact they too could be injured or killed. Of course if you only have a low power hand held transceiver as you main station rig then such advice does not apply as the unit is designed with safety in mind. However today there is a big question mark hanging over the use of handheld radio equipment as is discussed in the press in relation to mobile phones. So have your aerials as high as possible out of the way of , and protected from, High Voltage Mains Cables. ### LIGHTNING There is not much you can do to protect the station from a direct hit but the radio receiver input is very sensitive so when there is a storm brewing disconnect the aerial from the radio and then the radio will have a better chance of not being damaged due to large amounts of static discharge. Also in a storm it is good practice to disconnect the mains plugs as well.
#### Safe use of headphones Now most people will have at one time or another been to a pop concert when the music is very loud. Well it is known that prolonged exposure to such an environment can lead to damage of the hearing. What some people may not know is that the uses of excessive volume of audio into headphones can also result in damage to hearing. When using headphones the audio volume only needs to be turned up just sufficiently for you to be able to hear the communication. Even so prolonged use of head phone could impair hearing. Be careful!! Even at normally low volume levels pops and bangs which can be experienced when changing frequency if suffered for too long will also damage hearing. ### TAKE CARE of YOUR EARS
### Tools used in the shack Tools in every day use in the shack can be dangerous. The knife used to cut wire can equally cut your hand, the cutters used to aid removal of the outer cover from cables can also pinch fingers or worse cut them off !!!! The soldering iron gets very hot - it would burn your skin and clothes if it touched them. Also drops of molten solder can drop on your feet, hands or carpets also causing burns and damage. ## BE CAREFUL

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