Work using electrically powered equipment

You should make sure that electrical equipment used for work is safe. Here are a list of actions that should be taken to ensure this is so:

Check that the electrical equipment is suitable

• The equipment should be physically capable of doing the job, and designed and constructed so that mechanical and electrical stresses do not cause the equipment to become unsafe.
• If the environment is damp you may choose to use battery or air powered equipment, or equipment that operates at a reduced voltage such as that supplied by a transformer with an output that is centre tapped to earth (this halves the voltage between a live wire and earth). These are used in the construction industry and are readily available from hire shops.
• If the environment is conductive with restricted movement (eg inside a metal tank) additional precautions are necessary. BS7671 'Requirements for Electrical Installations', IEE Wiring Regulations, Seventeenth edition, Section 706, gives guidance on this.
• If there is the chance that there is an explosive atmosphere (containing flammable aerosols, vapours, gases or dusts) nearby you should ensure the work can be carried out safely and that the right equipment is chosen. (see Resources)

[Back to top]

Check that the electrical equipment is in good condition

Many faults with work equipment can be found during a simple visual inspection:

• Switch off and unplug the equipment before you start any checks.
• Check that the plug is correctly wired (but only if you are competent to do so).
• Ensure the fuse is correctly rated by checking the equipment rating plate or instruction book.
• Check that the plug is not damaged and that the cable is properly secured with no internal wires visible.
• Check the electrical cable is not damaged and has not been repaired with insulating tape or an unsuitable connector. Damaged cable should be replaced with a new cable by a competent person.
• Check that the outer cover of the equipment is not damaged in a way that will give rise to electrical or mechanical hazards.
• Check for burn marks or staining that suggests the equipment is overheating.
• Position any trailing wires so that they are not a trip hazard and are less likely to get damaged.

If you are concerned about the safety of the equipment you should stop it from being used and ask a competent person to undertake a more thorough check.

Additional information on the visual inspection of electrical equipment is in the free guidance note Homeworking.

Additional regular inspections may be required where a risk assessment indicates this is necessary (such as where equipment is used in a harsh environment). These inspections should be performed by a competent person using suitable equipment, and often enough to ensure equipment does not become unsafe between the inspections.

The table below gives a list of suggested initial inspection intervals for different types of equipment. The combined inspection and test could be a Portable Appliance Test (PAT), or a detailed test with a more sophisticated instrument. You should make sure that the person carrying out the tests is trained and competent to do so. See the guidance booklet Maintaining portable and transportable electrical equipment for more information.

You may need to change how often inspections are being carried out if there are indications that equipment may become unsafe before the next inspection.

Type of business User checks Formal visual inspection Combined inspection and test Equipment hire N/A Before issue/after return Before issue Construction (see Electrical safety on construction sites for more detail) 110 V - Weekly 230 V mains - Daily/every shift 110 V - Monthly 230 V - weekly 110 V - Before first use on site then 3 monthly 230 V mains - Before first use on site then monthly Light industrial Yes Before initial use, then 6 monthly 6 months to 1 year Heavy industrial/high risk of equipment damage Daily Weekly 6 months to 1 year Office information technology eg desktop computers, photocopiers, fax machines No 1 to 2 years None if double-insulated, otherwise up to 5 years Double insulated equipment not hand-held, eg fans,table lamps No 2 to 3 years No Hand-held double insulated (Class II) equipment, eg some floor cleaners, kitchen equipment and irons Yes 6 months to 1 year No Earthed (Class I) equipment, eg electric kettles, some floor cleaners Yes 6 months to 1 year 1 to 2 years Equipment used by the public, eg in hotels By member of staff 3 months 1 year Cables and plugs, extension leads Yes 1 year 2 years

[Back to top]

Check that the electrical equipment is suitable for the electrical supply

Make sure that the electrical equipment you are intending to use is suitable for the electrical supply to which you are connecting it. Check the voltage is correct and that the supply can deliver the current required by the equipment (the power requirements of the equipment will be shown on its rating plate).

Check the electrical supply is safe to use

You should be sure that the electrical supply is safe to use. Regular tests performed by a competent person, using suitable equipment are a good way of reducing risks. Where there is evidence that the supply may not be safe, such as damaged equipment or wiring, the supply should not be used until work has been done to correct this. Some simple user checks can be carried out on electrical socket outlets using an electrical socket tester, but it is essential that the correct type of tester is used. If any doubt remains regarding the safety of the electrical supply, a competent person should be consulted.

[Back to top]

Use a Residual Current Device (RCD)

A Residual Current Device (RCD) can reduce the likelihood of an electrical injury but a shock can still cause very serious or fatal injuries, so an RCD should only be used as a secondary means of reducing the risk of people being injured by electricity. RCD's are not designed to prevent the ignition of an explosive atmosphere and should not be used for this purpose.

The best place for an RCD is built into the main switchboard, as this means that the electrical supply is permanently protected. If this is not possible, an electrical socket outlet incorporating an RCD, or a plug in RCD adaptor, can also provide additional safety.

If an electrical socket outlet incorporating an RCD, or a plug in RCD adaptor is used it should be tested, by the user, prior to use by operating the Test button. Faulty RCDs should not be used and either removed for use or labelled as faulty.

An RCD detects some, but not all, faults in the electrical system and rapidly switches off the supply, reducing the potential for injury caused by a common type of electric shock. To reduce the likelihood of injury to people the RCD should have a tripping current of not more than 30 milliamps (mA). RCDs with a higher tripping current are used to protect against fire.

Remember:

An RCD is a valuable safety device, never bypass it; if the RCD trips, it is a sign there is a fault. Check the system before using it again; if the RCD trips frequently and no fault can be found in the system, consult the manufacturer of the RCD; the RCD has a test button to check that its mechanism is free and functioning. Use this regularly.

If lighting circuits are protected by the same RCD that also protects other equipment, a fault that causes the RCD to trip will also result in the loss of lighting that could give rise to a number of risks (such as trips and falls or the dangers from moving machinery). You should perform a risk assessment to identify the effect of fitting an RCD to electrical circuits.

[Back to top]

One of the most important tools in your toolbox — both physically and in terms of your own experience and know-how — is a multimeter. Most people are leery of working with electricity, and for good reason: electricity can be dangerous when working on any appliance, and knowing when you’re doing something right or wrong can be tricky. Most appliances with electrical components go bad when some part of the circuit is no longer conducting electricity correctly, so being able to isolate the parts and test them will be a frequent part of your job. Here’s how:

How to Test Appliance Parts with Your Multimeter

The first step in any repair or troubleshooting job is to disconnect the appliance from the power source. This is true whether the device plugs into the wall or is hardwired into the house; in that circumstance, you’ll need to turn off the circuit breaker. This keeps both you and the customer safe, as well as the appliance and the house.

Then, you need to dismantle the appliance based on your best guess of the problem. If a microwave isn’t powering on, it could be the magnetron, or the transformer, but capacitors and diodes are the most likely components to break. WARNING: Working on a microwave can be dangerous and even life threatening, be sure you have been properly trained before attempting.  If you’re working on an appliance that’s supposed to generate heat, isolate components from the heat circuit. Knowing which parts are more likely to break or cause any of the most common problems helps you save time and means you only need to dismantle the appliance far enough to give you access to the likely culprit.

Once you have the component out of the appliance, you’re ready to use the multi-meter. These devices test a lot of things, and the most common are continuity, voltage, and resistance:

• Continuity tests measure if electricity can flow through the part. Plug the two probes into the multimeter and set the dial to ‘continuity.’ If you place the red and black probes on either side of the part (some parts have diodes and are one-directional so you need to arrange the probes accordingly), and you get a read of approximately zero, electricity can flow through the part. If it can’t, your multimeter will go towards one or displays OL for open loop.  The question is whether electricity is supposed to flow through or not.
• Resistance tests how much current is lost as electricity flows through a component or circuit. It’s measured in ohms, and it is slightly more complicated to test than continuity. Whereas continuity works on a range of zero to one (or OL), resistance can come in different strengths so you need to know how much resistance a given part should have. Then you’d manually set the range on your multimeter around that amount so the multimeter can provide a readout of if the resistance is lower or higher than that amount. You can fine tune the range by making it lower if the multimeter reads close to zero or by making it higher if it read one or OL (overload). Once you have a range in the device, place the probes on either side of the device to find the ohms of resistance.  The component should be isolated from any power source otherwise you can ruin your meter.  We prefer the use of an analog meter to accomplish this. 
• The third common test is for voltage, or the force of the electric pressure. You’ll need to know whether the appliance is DC (direct current) or AC (alternating current). Checking voltage can be very dangerous, be sure to get the proper training before attempting. Just like with resistance testing, you’ll need to manually set the expected range and make sure both the multimeter can handle the maximum expected voltage. Some components can be electrically ok, but a voltage check can ensure it is mechanically ok.

When you’re testing components, always start with continuity. Both resistance and voltage tests rely on electricity passing through the part, and the multimeter won’t know the difference between a part with the wrong resistance and a part with no continuity. You have to have the continuity information as a baseline for reading your other results.

Most people aren’t familiar with how to use a multimeter or what to do with the results once they have them. Becoming familiar with the common tests, what the readouts should be on functioning parts, and how to use the results to take next steps are some of the most important parts of the job. Go to Fred’s Appliance Academy here to learn more about how to fix parts and start learning which parts to test first on different appliances.

Spread the love