Tampering with isolator switches in the workplace is on the increase. Kevin McCarthy assesses the risks
The current trend of tampering with workplace isolator switches is rapidly becoming a life-threatening practice.
Tampering can involve deliberate interference, with criminal intent sometimes, to cause harm or damage.
As there cannot be much in the way of criminal intent to cause harm or damage on the average factory assembly line or in an office, shop or restaurant, why does my firm expend much research and effort into producing tamper-proof safety switches?
And why does Katko make safety switches as opposed to isolator switches?
To answer the first question, our research shows that tampering with electrical machinery or systems frequently can and does take place. Many of those doing it would be mortified if you accused them of tampering. Their motives are entirely innocent. They were trying to bypass, or override a procedure and were genuinely unaware they were doing anything dangerous.
Such ‘helpful’ interventions by the workforce, as many businesses know to their cost, can be dangerous or even lethal.
Take the following hypothetical situation of routine maintenance to a factory production line.
Unbeknown to the maintenance engineer, some bright spark has been able to remove the cover off the cheap isolator switch installed on the production machinery. This isolator is not a ‘safety switch’ and does not have the benefit of an interlock when it is in the ‘padlocked off’ position.
The maintenance engineer switches off the power supply and presumes that it is safe to work under the machinery. Subsequently, along comes a worker who overrides the isolator switch and switches the power back on.
I leave it to your imagination as to what injuries might be sustained by a hapless maintenance engineer trapped beneath a moving assembly line.
The factory owners will be liable for big compensation to the maintenance engineer and, in a worst-case scenario, his widow and family, all because of the false economy of installing an old-fashioned, unfit-for-purpose isolator switch, not a safety switch.
Regrettably, many electrical wholesalers, electrical contractors and maintenance electricians in the UK risk installing such switches, happy to make cost savings wherever possible.
In addition, some specifiers and their clients, also eager to make a short-term financial saving, are signing off on the decision. This is a bad decision for two main reasons.
First, there are many different kinds of isolator switch on the market, and the majority of them are unfit for purpose. Most are quite simply not up to the job of providing the high levels of safety and durability needed on a factory production line.
And all can easily be compromised by anyone from the client’s workforce who has a modicum of electrical knowledge.
Another reason why most cheap specs are unfit for purpose is their highly misleading short- circuit rating. Virtually all switch manufacturers claim that their 25 A AC21-rated switch is suitable for use with a 7.5 kW motor at AC23.
However, they also claim a short-circuit rating of 50 KA with a back-up fuse of 25 A. As the full-load current of a 7.5 kW motor is up to 15 A, and the starting current is up to eight times this value (120 A), the chances are that a 25 A back-up fuse will blow, causing nuisance tripping.
This is why motor manufacturers recommend a 63 A back-up fuse, and why Katko tests its 50 KA short-circuit rating with a 63 A fuse as standard on the 25 A safety switch.
So the safety switches manufactured by Katko are impossible to compromise. Even placing the switch in the ‘padlocked off’ position activates an interlock, which eliminates the possibility of someone attempting to remove the cover and override the on/off switch.
The technical specification of a Katko safety switch is of a higher standard than a traditional rotary isolator, and you will pay a little more. But it means safeguarding workers in the workplace and protecting an electrical contracting firm’s reputation for safe and reliable workmanship.
These are the two main reasons why a reputable safety switch needs to be installed at all times.
Also, there is the host of existing and upcoming legislation relating to electrical installations. Suffice it to say that Katko’s safety switch is probably the switch of choice throughout mainland Europe.
Why does Katko make only safety switches? A major reason is that we, like electrical contractors and maintenance electricians, have a reputation to protect.
Katko is proud to be able to print the words ‘safety switch’ on every piece of packaging and to identify each kind of safety switch clearly and individually on the box, so that our customers always have the right switch for the job.
In addition, the packaging carries information regarding the switch’s accreditations, technical specifications, installation instructions and safety features. This makes selection easier when you are visiting your wholesaler’s trade counter.
Electrical contractors that I have spoken to quickly recognise the need for a safety switch on a factory production line. However, those same contractors think it is still OK to fit any old isolator switch on, say, an air-conditioning system in a restaurant, or dry-cleaning equipment in a shop.
Take the example of a service engineer visiting a restaurant to repair an air-conditioning system. Noticing that there is no isolator switch, he enters the premises to turn the power off at the on/off switch and commences to work on the system.
The restaurant manager subsequently notices that the dining room needs freshening up and turns on the air-conditioning system.
The question here is, how many fingers did the service engineer lose?
I hope this makes the point that safety can be compromised if you opt to install a traditional isolator switch. And whatever electrical installation you are contracted to do deserves the seal of safety – a fit-for-purpose safety switch.
- Katko has a leaflet on differences between isolator switches and safety switches. Email: firstname.lastname@example.org
Electrical and Mechanical Contractor
Kevin McCarthy is managing director of Katko UK