OK, following receipt of more very useful comments, herewith (below) Draft 3 – which I hope may be the final draft prior to producing a version to post to the wiki. It can obviously be revised whenever anyone wants, but I want to get to a version which everyone (everyone who comments) regards as ‘acceptable’ to be on public view before uploading it to the wiki.
To aid your review, I have indicated all changes since the last version (Draft 2) in red. In relation to my ‘major outstanding issues’, I’ve not had a lot of assistance, so I’ve had to make some tenative ‘executive decisions’. I therefore suspect that some of my ‘new bits’ will generate some comments and/or disagreements, so please don’t hold back!
Given the lack of any clear agreement on what we should say about ‘how to isolate’ (SP or DP, particularly with TT), in addition to the ‘primary’ version, I’ve offered two alternative versions of that section for consideration.
I hope to be able to ‘finalise’ and post to the wiki pretty soon – so, as always, would be grateful for any comments as soon as you can manage – and the more (‘no holds barred’) comments the better!
Kind Regards, John
THE RISKS
Electricity can, and does, kill, but much more commonly results in (possibly life-changing) serious burns and other serious injuries, including loss of fingers, limbs, sight etc. Residual current devices (RCDs) reduce, but do not eliminate, the risks of death and serious injury due to electric shock. Serious injury, and possibly even death, can also result from falls from ladders etc. precipitated by electric shocks, and RCDs will not reduce that risk. Do not be complacent – catastrophes and tragedies really do happen.
BEFORE YOU START - GENERAL SAFETY ADVICE
Only undertake any electrical work if you are competent to do so – i.e. if you fully understand what you are doing and what safety precautions need to be taken. If in doubt, seek advice or professional assistance. If problems, uncertainties or things you don’t understand arise whilst you are doing the work, stop doing it and seek advice or professional assistance. Do not put yourself or those around you at risk by guessing or by trying to do things you don’t fully understand or which are beyond your capabilities.
Before working on any electrical circuit or item, you must disconnect (‘isolate’) it from the electricity supply and then confirm that it is no longer ‘live’. This is called ‘testing for dead’.
With the single exception of when you are ‘testing for dead’, you should never work on any electrical circuit or item which is, or may be, live. When ‘testing for dead’, be extremely careful not to touch any possibly live parts. Wearing rubber gloves (or, better than nothing, PVC ‘washing up’ gloves) will reduce the chance of your coming into contact with live parts. Never interfere with the electricity supplier’s fuse’s, the electricity meter or any of the cables to/from them.
When doing electrical work, you should not wear metallic jewellery or watches on your hands or wrists, or around your neck, and if you have metal-framed or metal-armed spectacles, use a neck cord so that they cannot fall into your work. Nasty accidents can, and do, happen as a result of such metallic items coming into contact with live electrical parts. Long hair (which can conduct electricity) should also be tied up ‘out of the way’. Wherever possible do not work on an electrical installation unless someone else is around – just in case, despite all precautions, something happens to you.
BEFORE YOU START - SAFETY EQUIPMENT NEEDED - VOLTAGE DETECTOR
Before you undertake any electrical work, you should acquire a voltage tester for confirming that circuits are ‘dead’ and therefore safe to work on (‘testing for dead’). Ideally this should be a ‘two-pole voltage tester’ (i.e. one that you actually ‘touch’ onto two places in the circuit under test) – either with a lamp or an LED/electronic display. A less satisfactory tool is a multimeter, set to a high (at least 300V) AC voltage range but, if you use this, be sure that the probes are such as to prevent you touching live parts when using them. ‘Neon test screwdrivers’ (and ‘non-contact voltage detectors’) are unreliable to the point of being potentially dangerous (may fail to indicate voltage when a dangerous voltage is present) and therefore should not be used to confirm that circuits are safe to work on (‘testing for dead’).
THE SAFE WAY TO UNDERTAKE ELECTRICAL WORK
To work safely, you should undertake the following steps, in the order given:
1: CONFIRM (‘PROVE’) YOUR VOLTAGE DETECTOR IS WORKING PROPERLY
Do this ‘proving’ by testing your voltage detector on a known voltage source, which requires you to gain access to live conductors to which to connect your tester. Electricians will often have an adaptor or ‘test lead’ (which they plug into a socket) for this purpose. One can gain access to live conductors at a ceiling lighting ‘rose’, the cover of which can usually be unscrewed by hand (with the power to the circuit temporarily switched off – switching off the light switch alone is not safe, since it will often leave some live parts within the rose), but there are then hazards associated with having to use the tester ‘above your head’, probably when standing on a ladder. Use of an adaptor or test lead plugged into a socket is the easiest/safest approach. If you want further suggestions/advice regarding ways of doing this ‘proving’, you may wish to ask a question in the forum. Whatever approach you use, be extremely careful not to touch anything live whilst ‘proving’ (see general safety advice above) – remember that when using your voltage detector is the one and only situation in which you should be working on ‘live’ circuits, which you should treat with great caution and respect.
2: ISOLATE (DISCONNECT ELECTRICITY FROM) THE CIRCUIT YOU WILL BE WORKING ON
You must isolate (disconnect electricity from) the circuit you will be working on before you open up any accessories (sockets, switches etc.) on that circuit. The safest approach is to switch off the ‘Main Switch’ of your Consumer Unit (CU) or fuse board, thereby switching off all electricity in your house (if you have an old-fashioned installation with two or more fuse boxes/boards, switch them all off). The next-safest approach is to switch of the ‘miniature circuit breaker’ (MCB), or remove the fuse, of the circuit you will be working on (plug-in Wylex MCBs can also be pulled out, like fuses, after switching off). Switching off just a light switch in order to work on a light fitting or ceiling rose etc. is not safe, since it will often leave some live parts at the fitting or rose.
Alternative A: 2: ISOLATE (DISCONNECT ELECTRICITY FROM) THE CIRCUIT YOU WILL BE WORKING ON
You must isolate (disconnect electricity from) the circuit you will be working on before you open up any accessories (sockets, switches etc.) on that circuit. The only really safe approach is to switch off the ‘Main Switch’ of your Consumer Unit (CU) or fuse board, thereby switching off all electricity in your house (if you have an old-fashioned installation with two or more fuse boxes/boards, switch them all off). In particular, note that switching off just a light switch in order to work on a light fitting or ceiling rose etc. is not safe, since it will often leave some live parts at the fitting or rose.
Alternative B: 2: ISOLATE (DISCONNECT ELECTRICITY FROM) THE CIRCUIT YOU WILL BE WORKING ON
You must isolate (disconnect electricity from) the circuit you will be working on before you open up any accessories (sockets, switches etc.) on that circuit. The safest approach is to switch off the ‘Main Switch’ of your Consumer Unit (CU) or fuse board, thereby switching off all electricity in your house (if you have an old-fashioned installation with two or more fuse boxes/boards, switch them all off). If you are absolutely certain that your electrical installation has a ‘TN’ (or ‘PME’) earthing system (i.e. an earth provided by your electrical supplier, from their incoming supply cable or ‘supply head’), then the next-safest approach is to switch off the ‘miniature circuit breaker’ (MCB), or remove the fuse, of the circuit you will be working on (plug-in Wylex MCBs can also be pulled out, like fuses, after switching off). Switching off just a light switch in order to work on a light fitting or ceiling rose etc. is not safe, since it will often leave some live parts at the fitting or rose. If you are uncertain about your installation’s earthing system, or if you know it is ‘TT’ (using an ‘earth rod’ outside of your house), then you must use the ‘main switch’ (or equivalent) for isolation
3: IF POSSIBLE, ENSURE THAT THE ELECTRICITY CANNOT BE SWITCHED BACK ON WHILST YOU ARE WORKING
If you have removed a fuse or plug-in MCB, put it in your pocket. If the CU/fuse board is in a lockable room, lock it and put the key in your pocket. If the room is not lockable, locks for most MCBs and Main Switches are available. Consider putting a warning notice on the CU to warn against switching on the electricity. If none of those are possible, at least make sure that you warn anyone who might switch the electricity back on.
4: TEST THE CIRCUIT ‘FOR DEAD’ USING YOUR VOLTAGE DETECTOR
Test between Live and Neutral, between Live and Earth and between Neutral and Earth. You may think this is unnecessary, and that just testing between Live and Neutral or Live and Earth would be adequate, but there are some (admittedly uncommon) situations in which this could fail to detect the presence of dangerous voltages. Note that if you have isolated the circuit by switching off an MCB or removing a fuse, any RCD protecting the circuit will probably trip when you conduct the Neutral-Earth test, thereby removing electricity from circuits other than the one you are working on. Again, be extremely careful not to touch anything live whilst testing (see general safety advice above) – as mentioned above, remember that when using your voltage detector is the one and only situation in which you should be working on ‘live’ circuits, which you should treat with great caution and respect.
5: IF A POWER SOURCE IS STILL AVAILABLE, USE IT TO CONFIRM THAT YOUR VOLTAGE DETECTOR IS STILL WORKING PROPERLY
Unless you have a battery powered ‘proving unit’ (which you probably won’t have), this will generally not be possible if you have isolated using a ‘Main Switch’, and therefore have no electricity source available in your house. However, if a power source is available, it gives extra reassurance.
6: DO THE WORK. AS FAR AS IS POSSIBLE, TREAT CONDUCTORS AS IF THEY WERE LIVE, EVEN THOUGH YOU HAVE ‘TESTED THEM FOR DEAD’
Wherever possible, avoid touching conductors at all, either directly or with non-insulated metal tools. Use insulated tools if possible. If you have to, or may, touch a conductor, try to avoid having your other hand anywhere near any conductor or anything metallic (behind your back or in your pocket is the ideal place for the other hand, although that’s not always practical) – the most dangerous electric shocks are those which go from one hand to the other.
Think, and then think again, at every stage. If in any doubt, don’t do it, or if doubts/uncertainties arise whilst you are working, stop doing it – and seek advice or professional assistance. It’s just not worth risking the life and limb of yourself and those around you. If you have any questions, or want further advice about safe working, please do not hesitate to ask questions in the forum – that’s what it is there for!
To aid your review, I have indicated all changes since the last version (Draft 2) in red. In relation to my ‘major outstanding issues’, I’ve not had a lot of assistance, so I’ve had to make some tenative ‘executive decisions’. I therefore suspect that some of my ‘new bits’ will generate some comments and/or disagreements, so please don’t hold back!
Given the lack of any clear agreement on what we should say about ‘how to isolate’ (SP or DP, particularly with TT), in addition to the ‘primary’ version, I’ve offered two alternative versions of that section for consideration.
I hope to be able to ‘finalise’ and post to the wiki pretty soon – so, as always, would be grateful for any comments as soon as you can manage – and the more (‘no holds barred’) comments the better!
Kind Regards, John
THE RISKS
Electricity can, and does, kill, but much more commonly results in (possibly life-changing) serious burns and other serious injuries, including loss of fingers, limbs, sight etc. Residual current devices (RCDs) reduce, but do not eliminate, the risks of death and serious injury due to electric shock. Serious injury, and possibly even death, can also result from falls from ladders etc. precipitated by electric shocks, and RCDs will not reduce that risk. Do not be complacent – catastrophes and tragedies really do happen.
BEFORE YOU START - GENERAL SAFETY ADVICE
Only undertake any electrical work if you are competent to do so – i.e. if you fully understand what you are doing and what safety precautions need to be taken. If in doubt, seek advice or professional assistance. If problems, uncertainties or things you don’t understand arise whilst you are doing the work, stop doing it and seek advice or professional assistance. Do not put yourself or those around you at risk by guessing or by trying to do things you don’t fully understand or which are beyond your capabilities.
Before working on any electrical circuit or item, you must disconnect (‘isolate’) it from the electricity supply and then confirm that it is no longer ‘live’. This is called ‘testing for dead’.
With the single exception of when you are ‘testing for dead’, you should never work on any electrical circuit or item which is, or may be, live. When ‘testing for dead’, be extremely careful not to touch any possibly live parts. Wearing rubber gloves (or, better than nothing, PVC ‘washing up’ gloves) will reduce the chance of your coming into contact with live parts. Never interfere with the electricity supplier’s fuse’s, the electricity meter or any of the cables to/from them.
When doing electrical work, you should not wear metallic jewellery or watches on your hands or wrists, or around your neck, and if you have metal-framed or metal-armed spectacles, use a neck cord so that they cannot fall into your work. Nasty accidents can, and do, happen as a result of such metallic items coming into contact with live electrical parts. Long hair (which can conduct electricity) should also be tied up ‘out of the way’. Wherever possible do not work on an electrical installation unless someone else is around – just in case, despite all precautions, something happens to you.
BEFORE YOU START - SAFETY EQUIPMENT NEEDED - VOLTAGE DETECTOR
Before you undertake any electrical work, you should acquire a voltage tester for confirming that circuits are ‘dead’ and therefore safe to work on (‘testing for dead’). Ideally this should be a ‘two-pole voltage tester’ (i.e. one that you actually ‘touch’ onto two places in the circuit under test) – either with a lamp or an LED/electronic display. A less satisfactory tool is a multimeter, set to a high (at least 300V) AC voltage range but, if you use this, be sure that the probes are such as to prevent you touching live parts when using them. ‘Neon test screwdrivers’ (and ‘non-contact voltage detectors’) are unreliable to the point of being potentially dangerous (may fail to indicate voltage when a dangerous voltage is present) and therefore should not be used to confirm that circuits are safe to work on (‘testing for dead’).
THE SAFE WAY TO UNDERTAKE ELECTRICAL WORK
To work safely, you should undertake the following steps, in the order given:
1: CONFIRM (‘PROVE’) YOUR VOLTAGE DETECTOR IS WORKING PROPERLY
Do this ‘proving’ by testing your voltage detector on a known voltage source, which requires you to gain access to live conductors to which to connect your tester. Electricians will often have an adaptor or ‘test lead’ (which they plug into a socket) for this purpose. One can gain access to live conductors at a ceiling lighting ‘rose’, the cover of which can usually be unscrewed by hand (with the power to the circuit temporarily switched off – switching off the light switch alone is not safe, since it will often leave some live parts within the rose), but there are then hazards associated with having to use the tester ‘above your head’, probably when standing on a ladder. Use of an adaptor or test lead plugged into a socket is the easiest/safest approach. If you want further suggestions/advice regarding ways of doing this ‘proving’, you may wish to ask a question in the forum. Whatever approach you use, be extremely careful not to touch anything live whilst ‘proving’ (see general safety advice above) – remember that when using your voltage detector is the one and only situation in which you should be working on ‘live’ circuits, which you should treat with great caution and respect.
2: ISOLATE (DISCONNECT ELECTRICITY FROM) THE CIRCUIT YOU WILL BE WORKING ON
You must isolate (disconnect electricity from) the circuit you will be working on before you open up any accessories (sockets, switches etc.) on that circuit. The safest approach is to switch off the ‘Main Switch’ of your Consumer Unit (CU) or fuse board, thereby switching off all electricity in your house (if you have an old-fashioned installation with two or more fuse boxes/boards, switch them all off). The next-safest approach is to switch of the ‘miniature circuit breaker’ (MCB), or remove the fuse, of the circuit you will be working on (plug-in Wylex MCBs can also be pulled out, like fuses, after switching off). Switching off just a light switch in order to work on a light fitting or ceiling rose etc. is not safe, since it will often leave some live parts at the fitting or rose.
Alternative A: 2: ISOLATE (DISCONNECT ELECTRICITY FROM) THE CIRCUIT YOU WILL BE WORKING ON
You must isolate (disconnect electricity from) the circuit you will be working on before you open up any accessories (sockets, switches etc.) on that circuit. The only really safe approach is to switch off the ‘Main Switch’ of your Consumer Unit (CU) or fuse board, thereby switching off all electricity in your house (if you have an old-fashioned installation with two or more fuse boxes/boards, switch them all off). In particular, note that switching off just a light switch in order to work on a light fitting or ceiling rose etc. is not safe, since it will often leave some live parts at the fitting or rose.
Alternative B: 2: ISOLATE (DISCONNECT ELECTRICITY FROM) THE CIRCUIT YOU WILL BE WORKING ON
You must isolate (disconnect electricity from) the circuit you will be working on before you open up any accessories (sockets, switches etc.) on that circuit. The safest approach is to switch off the ‘Main Switch’ of your Consumer Unit (CU) or fuse board, thereby switching off all electricity in your house (if you have an old-fashioned installation with two or more fuse boxes/boards, switch them all off). If you are absolutely certain that your electrical installation has a ‘TN’ (or ‘PME’) earthing system (i.e. an earth provided by your electrical supplier, from their incoming supply cable or ‘supply head’), then the next-safest approach is to switch off the ‘miniature circuit breaker’ (MCB), or remove the fuse, of the circuit you will be working on (plug-in Wylex MCBs can also be pulled out, like fuses, after switching off). Switching off just a light switch in order to work on a light fitting or ceiling rose etc. is not safe, since it will often leave some live parts at the fitting or rose. If you are uncertain about your installation’s earthing system, or if you know it is ‘TT’ (using an ‘earth rod’ outside of your house), then you must use the ‘main switch’ (or equivalent) for isolation
3: IF POSSIBLE, ENSURE THAT THE ELECTRICITY CANNOT BE SWITCHED BACK ON WHILST YOU ARE WORKING
If you have removed a fuse or plug-in MCB, put it in your pocket. If the CU/fuse board is in a lockable room, lock it and put the key in your pocket. If the room is not lockable, locks for most MCBs and Main Switches are available. Consider putting a warning notice on the CU to warn against switching on the electricity. If none of those are possible, at least make sure that you warn anyone who might switch the electricity back on.
4: TEST THE CIRCUIT ‘FOR DEAD’ USING YOUR VOLTAGE DETECTOR
Test between Live and Neutral, between Live and Earth and between Neutral and Earth. You may think this is unnecessary, and that just testing between Live and Neutral or Live and Earth would be adequate, but there are some (admittedly uncommon) situations in which this could fail to detect the presence of dangerous voltages. Note that if you have isolated the circuit by switching off an MCB or removing a fuse, any RCD protecting the circuit will probably trip when you conduct the Neutral-Earth test, thereby removing electricity from circuits other than the one you are working on. Again, be extremely careful not to touch anything live whilst testing (see general safety advice above) – as mentioned above, remember that when using your voltage detector is the one and only situation in which you should be working on ‘live’ circuits, which you should treat with great caution and respect.
5: IF A POWER SOURCE IS STILL AVAILABLE, USE IT TO CONFIRM THAT YOUR VOLTAGE DETECTOR IS STILL WORKING PROPERLY
Unless you have a battery powered ‘proving unit’ (which you probably won’t have), this will generally not be possible if you have isolated using a ‘Main Switch’, and therefore have no electricity source available in your house. However, if a power source is available, it gives extra reassurance.
6: DO THE WORK. AS FAR AS IS POSSIBLE, TREAT CONDUCTORS AS IF THEY WERE LIVE, EVEN THOUGH YOU HAVE ‘TESTED THEM FOR DEAD’
Wherever possible, avoid touching conductors at all, either directly or with non-insulated metal tools. Use insulated tools if possible. If you have to, or may, touch a conductor, try to avoid having your other hand anywhere near any conductor or anything metallic (behind your back or in your pocket is the ideal place for the other hand, although that’s not always practical) – the most dangerous electric shocks are those which go from one hand to the other.
Think, and then think again, at every stage. If in any doubt, don’t do it, or if doubts/uncertainties arise whilst you are working, stop doing it – and seek advice or professional assistance. It’s just not worth risking the life and limb of yourself and those around you. If you have any questions, or want further advice about safe working, please do not hesitate to ask questions in the forum – that’s what it is there for!
