Nothing can be taken granted when it comes to electrical safety, writes Michelle Knott, not least whether the power source is properly isolated.
“There are around 1,000 serious accidents per year at work due to contact with electricity… many of which could be avoided by following simple procedures and using the right equipment to the latest standards,” says Martindale’s director of marketing, Andrew Holland.
In the process industries, part of the challenge is the multidisciplinary nature of projects and maintenance regimes. Electricians should be aware that many of the people working around them are fitters, for example, not trained electricians.
In addition, general in-house maintenance and service teams working on plant that’s adjacent to electrical equipment may need to shut off electrical systems effectively in order to work safely nearby.
There is a stronger focus on health and safety compliance today. Sentencing guidelines changed in 2016, leading to higher fines and a higher chance of imprisonment. Average fines for noncompliance have tripled over the last year
Andrew Holland, director of marketing, Martindale
The ability to apply consistent safety rules and procedures is made even more complicated by the fact that a large process facility may have personnel from a number of different contractors and suppliers working in parallel with in-house maintenance teams across the site at any given time.
These challenges have always been there, but there are also reasons why the focus on electrical safety has been creeping up the boardroom agenda in recent months.
First, more employers are using non-specialists in their general maintenance teams to carry out jobs that potentially put them at risk if proper electrical safety procedures aren’t followed. “There are some big commercial organisations that have decided in recent years to bring more of their maintenance work in-house, rather than bringing in specialist contractors,” says Holland.
There has also been a ratcheting up of sanctions over the past year for noncompliance with health and safety regulations (such as The Management of Health and Safety at Work Regulations 1999 and the Electricity at Work Regulations 1989), and that has focused the minds of employers on electrical safety.
“There is a stronger focus on health and safety compliance today. Sentencing guidelines changed in 2016, leading to higher fines and a higher chance of imprisonment. Average fines for noncompliance have tripled over the last year,” says Holland.
The IET sets out a number of useful guidelines but the main one is Safe Isolation, which is all about how to make sure you’ve isolated the equipment you’re working on
Peter Wade, UK LVI sales team leader, Megger
For instance, at the end of November 2017, one company in the North East was fined £900,000 plus costs for an incident in which a contractor cut through an electric cable to a fan and was electrocuted. The contractor made a full recovery but the accident was potentially fatal.
HSE inspector Shuna Rank said at the time: “This incident could so easily have been avoided if the work had been properly planned, the risks identified and steps taken to ensure that all equipment was electrically safe before the contractors started work at the site.”
With all this in mind, guidance requires operators to ‘work dead’ whenever possible and to achieve this by following a clearly defined procedure that involves isolating the source of supply, locking off the supply and proving that electrical systems are dead before any maintenance work is carried out.
There are various sources of guidance available. For example, there’s the Best Practice Guide from Electrical Safety First: Guidance on the management of electrical safety and safe isolation procedures for low voltage installations.
The Institution of Engineering and Technology (IET) also produces a series of guidance notes for people working with electricity. “The IET sets out a number of useful guidelines but the main one is Safe Isolation, which is all about how to make sure you’ve isolated the equipment you’re working on,” says Peter Wade, UK LVI sales team leader with Megger.
“Provided you’re using the right test equipment to prove that a circuit is live and then that it’s dead, it shouldn’t really be an issue.”
In practice, ensuring that everyone is using the correct equipment is easier said than done, however. For example, it may be tempting to use a basic multimeter, but that could be courting disaster, according to Wade: “There are so many inexpensive multimeters on the market, but if the voltage [in the circuit] isn’t high enough it may not register or may give a false reading. People should be using dedicated two-pole testers and proving units.”
Tools of the trade
“Ensuring the right tools are available for the job might seem like common sense, but it’s still an issue among some maintenance teams, who may be potentially putting their lives and those of their colleagues at risk,” agrees Holland.
“For example, using a multimeter to prove a circuit is dead is not permissible as it could easily give a misleading reading if set to the wrong range or if the batteries need replacing.
“A dedicated voltage indicator with no ranges, switches or batteries is by far the most reliable method for proving dead. Having the right locking off device to hand for all types of common circuit breakers or fuse holders is a must.”
For these reasons the guidelines are clear that electricians and maintenance teams should use a dedicated voltage indicator and proving unit so they can be absolutely certain that a circuit is dead before starting work.
Many voltage indicators, such as Martindale’s VI13800 and VI-15000, says Holland, do not require batteries and are dedicated to measuring voltage only, avoiding any potential errors that might otherwise occur from using a tester on the wrong setting.
The proving unit is needed to demonstrate the correct functioning of the voltage indicator before and after testing that the supply is isolated.
Operators could instead use a known live source to test that a voltage indicator is working correctly, provided there is a live source close by that can be accessed safely.
However, the guidance recommends using a dedicated proving unit, because a live source may only light up some of the LEDS on the tester, whereas a matched proving unit will ensure that the tester is functioning correctly across the entire range.
In an ideal world, flipping a switch to turn things off would be enough to ensure that a system is dead. However, Holland cautions that poor wiring may mean that is not the case: “It should never be assumed that equipment is dead because a particular isolation device has been placed in the OFF position. There are recorded instances where neutrals lines are ‘borrowed’, and while this is not permitted by wiring regulations, it is unfortunately not uncommon. In this instance, although a particular circuit may be locked off, the neutral conductor can become live, if an energised load on another circuit is connected to it. Guidelines require the circuit be proved dead before work is carried out.”
Many contractors are now turning to complete safe isolation kits, with the necessary equipment to safely lock off the circuit worked on and prove dead. For instance, the latest kits from Martindale now include matching voltage indicators and proving units and contain a complete range of locking off devices and hazard warning labels for all types of site and installation. The aim of the kits is to keep everything to hand and simplify any compliance issues with the latest test equipment standards.
Selection of test equipment in a technician’s toolkit depends on preference and what type of testing most often needs carrying out. Wade notes that the advent of multifunction testers (such as Megger’s MFT1701 series) makes it easier to streamline the number of instruments required by offering tests for insulation, RCD (residual current device) and loop testing in one package.
Multifunction testers are aimed at electrical installations and should not be confused with multimeters, primarily aimed at testing electronics.
