by ericmark »
Sat Jul 23, 2016 2:35 am
[quote="Johnny Curtis"]SAFETY TIPS ON HANDLING ELECTRICITY
Electrical cables are everywhere from streets, houses and to buildings. They are vast network of wiring that supply hundreds or thousands of volts of electricity. Dealing with electrical problems demands serious thought and safety considerations.
1. Always wear rubber gloves and sneakers when fixing electrical problems.
[/quote]Why? If the power has been turned off and proved dead there is one would hope very little chance of it becoming live. Wearing rubber gloves when working on the system live yes, but with a few exceptions you should not work on the system live. Rubber gloves often mean terminals not tight enough and there is also the problem of lactose intolerance. [quote="Johnny Curtis"]
2. Never attempt to reach a fruit from a tree adjacent to high voltage live wire.
[/quote]The high voltage lines should be kept well away from fruit trees, yes there may be some over sights, if that's the case phone the number on the pole or pylon and tell them of their error.[quote="Johnny Curtis"]
3. Do not overload a multi-socket plug adapter with appliance using electrical supply. It can cause overheating and eventually fire.
[/quote]You should not be able to overload a multi-socket they should have a fuse. Buying from UK supplier at least. Some Chinese Exports have been found to lack fuse protection. [quote="Johnny Curtis"]
4. Always turn off the main power switch before fixing electrical problems.
[/quote]Correct, the double pole isolator should be used, not the single pole MCB. With RCBO's you can get some double pole switching versions. But not only should it be switched off, but it should also be locked off. We are told insulation tape on the device is not good enough, neither is a do not switch on sign. But both should make people realise it is off because some one has switched it off, and it has not just tripped.[quote="Johnny Curtis"]
5. Recheck wires and cords for tears and worn covers. Unnoticed torn cords can pose hazards.
[/quote]This is what is covered with inspection and testing of in-service electrical equipment often called PAT testing, there is a series of user checks. But these should be done when not plugged in.[quote="Johnny Curtis"]
6. Search for electrical wire node boxes or wiring that can be affected by short circuits.[/quote]
What does that mean? There are some exceptions, but in the main wiring is always protected by an automatic disconnection device i.e. fuse. There are exceptions you are permitted 3 meters of cable between supply and fuse, but this is really something only found in distribution rooms between buzz bars and fuse box or like. The medical trade are allowed to use special red plugs without fuses where loss of supply could endanger life. But I would say searching for these unless your an electrician is wrong.
When writing any health and safety instruction set one has to be very careful, the instructions given in BS7671 have been changed and adapted many times to avoid any ambiguity. We see changes from rule of thumb to historically and the like where some one has misread the intended rule or recommendation.
I have been an electrician around the world for many years, on one site only have I seen the proving dead carried out, with pass removal if caught without the proving units. That was ICI Rock Savage. Even then the proving unit kicked out 500 volt only so although all lights may show at 500 volt you have no idea if the 50 volt lamp would actually work at 50 volt. Today the proving units go through the range of voltages.
And again they did not ask you to check current. Using a clamp on meter to test current you can detect the borrowed neutral, however I tend to use neon screwdrivers to alert me should some one have broken the borrowed neutral rule. Seeing sparks from a wire or seeing screwdriver light up as you remove the wire does give you a warning something is wrong.
For proving dead the tester should not have an on/off switch of any kind, multi-meters should not be used to prove dead, and the unit used to prove dead should be tested in proving unit both before and after.
One should test leakage on a 230 volt system with 500 volt and continuity with at least 250 mA and to test a RCD you need a special tester which can measure 0~40 milliseconds as well at the mA used.
Ability to automatically disconnect is normally tested using a loop impedance tester.
All these meters are expensive. And well beyond the purse of most DIY people. So in real terms DIY electrics are not safe. However 1000's of people do DIY electrics without killing themselves.
It is a real problem, as an electrician I know if I simply say you should not do DIY electrics no one will take any notice, so we need to take a middle ground, we can brooch in passing things like Part P, but we need to give advice trying to point out the pit falls, rather than harping on about the dangers.
There is a famous instruction set for starting a model T ford, it is quite complex, setting advance and retard, and selecting a gear to allow you to turn over the engine. However it seems they missed a step, and if followed to letter the car would have run over you. However it seems odd for USA no one got killed starting the car. Maybe because at that time you needed some intelligence to earn enough money to buy a car, and people looked out for their own safety.
