Tag Archives: current flow

General Safety Issues

IMPORTANT ELECTRICAL WORKPLACE SAFETY ADVICE (GUEST POST)

By Kyle Mitchell

Electrical safety in the workplace, just like anywhere else, is of paramount importance. As an owner of any kind of business where it is required for employees/members of the public to interact with electrical equipment, it’s extremely important that the safety of those people is a high priority, and it is also important that those people at work are aware of the potential dangers of electricity.

The following table outlines just how much of an effect electrical current can have on the human body:

Physiological effect 50Hz AC
Generally not perceptible 0.5mA
Threshold of perception, tingling sensation 1mA
Maximum “let go” current                                            5mA
Painful, can’t let go 10-20mA
Severe pain, muscular contraction, difficulty breathing 30mA
Possible Ventricular Fibrillation after 3 s, death possible 0.1A
Skeletal muscle damage – death likely 1.5A

 As can be seen, electricity isn’t to be trifled with. It’s a very real danger, and it’s important to respect electricity, and find ways to prevent electrical accidents in the workplace.  Here are some common errors in the workplace that can be avoided, simply by following regulations and being vigilant.

Appliances and Faulty Wiring

Appliances are extremely common in the workplace. From computers to power tools, it’s likely that practically everyone within the organisation at some point will have to use electrical appliances.

When using these, it’s important that the user always makes sure that wiring supplying electricity to the appliance is in good, safe working order. Educating your workers on the correct appearances of wires, and how to inspect them for obvious damage such as common faults, frays, exposed wiring or cracks within the casing will allow them to determine whether an appliance is safe for work or not.

If there’s something wrong with the wire, the appliance simply shouldn’t be used. It’s as simple as that.

Correctly Hiding Trailing Wires

Live wires supplying huge amounts of power should never be left exposed – they provide a huge danger to everyone, particularly because accidents can happen at absolutely any time.

By making sure wiring isn’t exposed, and is installed behind walls etc, it ensures that all of your employees are protected from the vast risks that exposed wiring can have to your employees.

Heating Equipment, Ovens Etc.

Although it may seem obvious, these forms of equipment pose a massive risk to the workplace. They’re a huge fire risk, and leaving such items unattended for long periods of time could be an extreme danger.

It is particularly important to assess any heaters that come from external sources (IE, your employees) as these could be faulty and directly cause a fire. Portable Appliance Testing should be carried out on these forms of equipment to ensure their operation is safe, and they should be constantly monitored and ALWAYS switched off.

Electrical Repairs

No matter how minor it might seem, electrical repairs should NEVER be carried out by anyone except a qualified electrician. As can be seen by the table above, electricity can be an extremely dangerous form of energy, and without the correct knowledge and respect of how it works, it is very hazardous for anyone to tamper with who doesn’t know what they’re doing.

If something is faulty within your organisation and you need it repairing, always contact a fully certified electrician to carry out the work for you. It is your responsibility as an employee to ensure the safety of your workers, and tampering with electrical equipment puts them at a truly massive danger.

Don’t Overload Plug Sockets

Ever seen those pictures of people who’ve literally built what seems to be a LEGO-inspired collection of double adapters and then plugged them into a socket? They’re scary photos, particularly as the added weight and amount of power being supplied out to electrical items creates a huge danger.

It’s important to either use a designated surge protector with multiple plug sockets that can lie on the floor or to either plug in one or two items to a plug socket. This makes sure that the plug socket can’t overload, causing electrical burns, sparks, or even fire.

Wet Hands/Feet

It’s one of the most common electrical safety pieces of advice given for a reason. Electricity and water simply don’t mix, and it is important that your company makes sure that any employees that have been exposed to water are not interacting with anything remotely electrical.

This extends from anything from plugs to appliances like PCs. It simply isn’t worth the risk to mix water and electricity, particularly as water acts as a source for current and can cause massive electrical shocks to the person with wet hands.

Electrical Overhead Power Lines

If anyone in your organisation works at a height, it is important to relay the dangers of electrical power lines. These overhead cables carry massive amounts of power, and are more likely to cause death than injury if touched.

Absolutely anybody working at a height must always make sure to check carefully for electrical cables.

Perform Regular Testing Procedures

Under several regulations it is the organisation’s responsibility to ensure the safety of all employees. In order to do this you should regularly make sure all equipment is inspected and passed as being completely safe by a certified individual, although regular inspection checks can be performed by employees who can flag up anything that might be amiss within the organisation’s equipment.

Similarly it is also important to regularly check the status of fixed wire installations throughout the building, as these can degrade over time and become increasingly more dangerous.  If fixed wire points are dangerous, anything plugged into power points can then become a hazard, so make sure these are regularly checked over to make sure that safety within the organisation is as good as it can be.

Have Staff Complete an Electrical Awareness Course

Although they’ll decrease your productivity for a few hours, having staff take part in an electrical awareness course will help them to understand the potential dangers electricity can have, and how to avoid accidents in the workplace.

A lot of it may seem like common knowledge but there’s every chance an employee doesn’t know the procedures and regulations relating to electrical equipment. By educating them in this field you turn your workplace from a potential minefield of dangerous electrical outlets to an educated area full of people with a larger amount of respect for the power of electricity.

Similarly, developing an electrical safety regulations guidebook for your organisations for people to refer to can also be a great help in raising electrical safety. 

The article was written by Kyle Mitchell, an employer of PASS ltd who specialise in testing equipment, electrical training and wire testing in the UK. You can visit their new website tester.co.uk for more, or visit the electrical testing section for equipment information. 

 Equipment Sales: www.tester.co.uk – www.pass-thermal.co.uk

Training: www.electricaltrainingcourse.co.uk – www.pat-testing-course.com

Thank you, Kyle, for this very important information regarding safety while working around electricity.  Most workplaces should have first aid kits available.  Employees should be furnished the correct dielectric personal protective equipment, (i.e., hardhats, boots or rubber-soled shoes, and dielectric glasses.) pb

General Safety Issues

TEN SAFETY PRECAUTIONS FOR WORKING ON ELECTRONIC PROJECTS (Guest Post)

Electricity is one mean monster you never want to mess with. It has its own rules which you ignore at your peril. Aside from the obvious ones – never work with live wires or use electrical devices near water – some are less obvious such as using the wrong type of component or not carrying out fail-proof voltage testing.   However simple or complex your electronic project, here are ten important ways you can stay safe. 

1) Discharge any capacitors.

Before working on any electrical equipment or appliance it’s crucial that you discharge all the capacitors, otherwise you might be in for a nasty shock or burn. 

1. Stop any alternating current flowing through the capacitor by unplugging the electronic device. 

2. Disconnect any capacitors that are removable. 

3. To discharge the capacitor touch the capacitor leads with the wires of an electronic bulb, a volt meter or a 5- to 10-watt resistor. If using a bulb, it will gradually dim and turn off to indicate the progress of the discharge. If using a resistor, touch the capacitor leads for just a few seconds for discharging. 

Some people discharge with a small screwdriver. However, the current discharged may be enough to melt the screwdriver’s tip, or the copper on the circuit board if the capacitor is still connected to it, as well as create sparks.

 2) Don’t bodge it, replace it. 

Electricity is too dangerous to risk a quick penny-pinching repair job. For instance, if you have a damaged length of cable never repair cuts with insulating tape; use a new length of cable instead.  

3) Don’t cut corners. Only a fool uses the wrong tool. 

Check and ensure you’re using the proper tools and equipment in any job. For example, when joining lengths of cable don’t bodge it with connector blocks covered in insulating tape or ‘splice’ wires by twisting them together, do a proper job using proper connectors instead. 

4) Avoid live heat-sinks

Choose your heat-sink wisely, particularly if you’re working with mains electricity. As with any semi-conductor, a triac produces a lot of heat to switch the main electrical currents through the transistors. To dissipate the heat and prevent overheating a heat-sink is incorporated. A BTA08-600 triac is commonly used which has an insulated heat-sink connection to the mains voltage, whereas the BTB08-600, which is almost identical, is not insulated. 

Although the non-insulated triac produces better thermal characteristics and is smaller, the insulated triac ensures that the heat-sink is not live so is safer to work with.  

5) Cover those parts – they could be live.

Your electronic equipment may have a label on the back giving you a stark warning like “CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK DO NOT REMOVE COVER (OR BACK).” This basically means there are parts inside which are unprotected from the mains voltage. If you have removed the cover from a device like this, always remember to need to fix it back before connecting to the mains.  

6) Protect against electronic static discharge.

To safeguard yourself and sensitive electronics against any static discharge always remember to get grounded or earthed first. “Earthed”, as the name suggests, refers to being connected to the earth or ground. One of the easiest ways is to be earthed is to wear an anti-static arm band connected by a wire to a metal cold water pipe (as this ends up in the earth or ground). As long as that pipe has eventual contact with the earth any static that builds up can be safely diffused through the earth rather than through you or via your tools to the sensitive electronics you’re working on. NB, a hot water pipe won’t work as it doesn’t have contact with the earth. Wearing cotton rather than man-made fibres is another added precaution you can take against static. 

7) Consider switching from mains electricity to low voltage electricity.

If you’re an electronics newbie, the safest way to practice your hobby is to completely avoid working with mains voltage. Most electronic circuits use low voltages, powered by batteries or an external plug-in transformer which converts the voltage down to a safe voltage (e.g. AC current to a low voltage DC current).  Make sure that the transformer has the appropriate voltage and rating for the type of circuit you’re using and the power supply it’s connected to. 

8) Safety when soldering.

Aside from dangers of working with electricity, soldering wires in your electronics project poses a few dangers of its own. The solder can get seriously hot, and air pockets can get into the solder that when heated can splatter you in the face. Be sure to wear eye protection safety goggles, allow the solder to cool down before touching it, wash your hands after use (as it contains poisonous lead) and solder in a well ventilated room to avoid the build-up of its mild toxic and caustic fumes. It’s also important to use the correct voltage of soldering iron for your project.  

9) Don’t overload your circuit.

Ensure that the cabling and all components in your circuit do not exceed the rating of the maximum current. This is especially important with heavy circuit loads such as lights and motors.    

10) Test and test again.

To test there that your circuit is absolutely dead you should always use a voltage meter. But can you be absolutely sure your voltage meter is giving you a proper reading? It may seem paranoid but voltage meters can fail (however rarely). Bearing in mind that it’s always better to be safe than sorry, check that your meter is working properly on a known source of voltage and regularly inspect its body, probes and wires for any signs of wear or damage. It it’s faulty or unreliable, replace. 

Louisa Logan is an electronic blogger, writing for sites like Element 14 and Farnell UK. She enjoys carrying out her own electrical experiments and has a passion for projects with Vishay capacitors and resistors.