Guide written by:
Jeremy, construction site supervisor, Cardiff
Working with electricity carries great risks if you don't follow a few basic safety guidelines: off-grid working, electrician's tools, personal protective equipment, etc. Electrocution is a major source of risk.
5 rules to follow when working with electricity
Any electrical work has the potential to be dangerous. Depending on the layout of the place you're working and the type of work you're doing, the risk of electrocution can be high if you don't take a few basic precautions. Here's what you need to know to foresee and avert potential accidents.
1. Always disconnect before you start
This means there is never current running when you begin work. Often this can be done with a circuit breaker or a fusebox trip switch. Once the circuit is disconnected, always check that there's no voltage using a multimeter, voltmeter, or continuity tester.
2. Only use the correct tools
All your tools should be insulated in order to protect you from accidental contact with live current. The best type are insulated up to 1000V, conforming to an international manufacturing standard. In terms of measuring instruments, a multimeter (or continuity tester) is essential, and should also conform to relevant standards.
3. PPE and safe working practices
To avoid arcing or accidental contact with current don't wear jewellery (rings, bracelets, watches, nacklaces etc.). Dress in well-fitting (i.e. not baggy) cotton clothes. Protective goggles are also a bonus, as are safety shoes with insulated soles. Depending on your experience and the type of work you're doing, specialized PPE (personal protective equipment) can also be useful, such as insulated gloves, insulated floor mats, a helmet, etc.
4. Clear working environment
Your working environment should be as clean and dry as possible. Don't keep things stored on the floor in order to avoid tripping; the same goes for electrical cables so you don't get your feet entangled. In humid locations, ventilate as much as possible before you start. In a similar way, minimize dust since it alters the electrical properties of the ambient air, making it more conductive and therefore hazardous.
5. Be aware of your limitations
Electricity is dangerous. If, having followed the previous four guidelines stringently, you're struggling to achieve what you wanted to, don't take unwise risks. A qualified electrician will be able to get to the bottom of it while staying completely safe.
What are the hazards?
When an electrical current passes through the human body, there are a variety of possible effects and some dramatic potential consequences. You need to be aware of these dangers if you want to carry out electrical work safely.
Severity of electrocution as a function of current:
- 1mA: prickling sensation in the skin
- 5mA: electric shock
- 10mA: muscular contortion (can prevent letting go of an object)
- 30mA: muscular spasms, and respiratory paralysis
- 75mA: cardiac fibrillation
- >1000mA (1A): cardiac arrest
Electroction: a case study
It's easy to see that even small current values can be dangerous (1mA = 0.001A). The risks are very real. To give a brief example, let's assume that the resistance of a human body on dry ground is about 1000 Ohms. Just by touching a 230V live wire (standard grid voltage), a current of 0.23A or 230mA will therefore pass through the body. If you don't take the relevant precautions (e.g. isolation with a circuit breaker), death could be around the corner.
Consequences of electrocution
These can be many and varied, but the most common results of an electric shock are:
- external burns at the points of contact
- internal burns along the length of the path taken by the electricity
- rhabdomyolysis, or destruction of internal body cells
- cardio-circulatory arrest following cardiac fibrillation
- asphyxia, resulting from muscular spasms
- secondary effects: it's not unusual for victims to fall, slide, or be thrown through the air. This can cause bruises, fractures etc.
How best to protect yourself?
The best way to protect yourself is to make sure you know what you're doing. Anyone can have a go at drawing, painting and even cookery (with mixed results), but you can't afford to blag it when it comes to electricity.
Today, electrical devices such as circuit breakers enable very rapid disconnection of current in case of anomalies in the network. But these devices aren't infallible, and as we've seen, exposure to a high current even for only a brief instant can be very dangerous.
The best kind of protection is to follow the guidelines given above, kit yourself out with the appropriate electrician's tools and keep them in good order, and above all else don't overestimate your abilities.
Learn more about workplace safety...
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Guide written by:
Jeremy, construction site supervisor, Cardiff, 128 guides
Electrician by trade, I first worked in industrial estates where I installed, wired and fixed a large number of electrical installations. After this, I managed a team of electricians for this type of work. 10 years or so ago, I turned to building and construction. From the modest family home, to gyms and theatres; I have been able to coordinate, audit and organise all sorts of construction sites. for 4 years now, I am restaoring and bulding an extrension to a bungalow in the heart of the welsh countyside. My experience in manual work and my knowledge means I am proud to be of service. Terraces, interior design, roofing, plumbing, electricty, anything goes! We have, my wife, daughter and I, built almost everything we have from scratch! So to answer all of your questions, and to orientate and advise you on coosing your tools? Easy!