Today’s test equipment contains safety features which were unheard of a few years ago so it pays to upgrade your kit to ensure maximum protection in your day to day activities. Here Malcolm Duncan of Klein Tools explains some of the features which you need to look out for.
If your job involves working with electricity then you will have a healthy respect for safety and yet the pressure of getting a job done can sometimes result in uncharacteristic mistakes. The importance of having the right test equipment can therefore never be underestimated and while safety arguably relies on a large dose of common sense, having the right equipment with all of the latest safety features ensures that you are always one step ahead.
As far as test equipment is concerned it needs to be tough and durable and able to withstand a few scrapes and bruises as part of the job. But it also needs to be designed and rated to the highest standards because when it comes to personal protection, your test equipment should not be the weak link.
One of the biggest mistakes which is made when choosing test equipment is to go for the cheapest model on the market and when times are tough this might seem like a sensible plan. However cheap doesn’t always mean cheerful which invariably means that cheaper models don’t always come with the safety features that you would expect or indeed which are advertised on the packaging. So what do you need to look out for when choosing test equipment?
Understanding IP ratings
There are a number of features which should be built into test equipment for your safety and to ensure reliability of the products. One of the first things to look out for is the IP or Ingress Protection rating as this will be a guide to how durable your test equipment will be over time. IP ratings are published by the International Electrotechnical Commission (IEC) and are used to measure the protection of enclosures around electronic equipment.
The IP rating is determined by specific tests designed to infiltrate electronic equipment with both solid objects and liquids. The protection level against the penetration of solid objects is measured is in a range of 0-6 where 0 provides no protection and 6 provides complete protection from everything – including dust. The protection level against the penetration of harmful liquids is measured in a range of 0-8 where 0 provides no protection and 8 provides complete protection against long periods of immersion under pressure.
Our Auto-Ranging Multi-Meter for example is rated at IP67 which means that it has complete protection against the ingress of solids (including dust) and is waterproof to Level 7 which ensures protection against the ingress of harmful liquids when it is immersed to a depth of up to 1 metre.
Drop test standards
The next feature which should be high on the list of priorities is the ability of the equipment to stand up to a small (or large) fall. Whilst most manufacturers will not condone this we have to be realistic because even the most careful person will drop things – sometimes out of the back of the van or sometimes from a greater height but when this happens the last thing you need is for your tester to give up the ghost.
Drop protection tests are therefore fairly standard practice for test equipment and the UL/IEC standard states that products should be able to withstand a drop of three feet onto a 50mm thick hardwood board supported by rigid steel or concrete.
In itself this is fairly satisfactory but in order to ensure that our products are even more robust we have taken this one step further. As a result our standard drop tests are carried out from a range of heights from 3 to 9.8 feet onto a rigid steel surface. The Dual-Range, Non-Contact Voltage Tester for example passed our tests which involved over 20 drops from 9.8 feet – without any damage.
Safety is the top priority
Choosing test equipment is a little bit like choosing a car in that the overall look and feel of the product is important, as is its ability to carry out basic tasks but it is perhaps the safety features which are the real selling point. In the same way that you wouldn’t buy a car without seat belts or air bags, you shouldn’t buy test equipment which isn’t rated high enough for the tasks which you carry out.
All modern test equipment is now designed to EN 61010 (Safety requirements for electrical equipment for measurement, control and laboratory use) which, in addition to high voltage design requirements, also includes other safety design constraints such as flammability and heat. This Standard offers a significantly higher level of safety for the user and manufacturers must meet all of the specifications in EN 61010 to receive the CE label.
The Standard addresses the issue of transient voltages (temporary voltage spikes) and classifies the Installation Category (often referred to as the Overvoltage Category) on a scale of CAT I to CAT IV.
The general rule which applies here is that the closer you are to the power source the higher CAT rating you require, so in theory if you are only using the tester for measurements which are typically performed on voltages from electronic circuits then you only need equipment which is rated at CAT I. A meter which is rated at CAT II would be suitable for measurements which are usually performed on voltages taken from a standard wall receptacle and a CAT III meter would be suitable for measurements which are taken when working with voltages on three phase equipment in fixed installations.
If you follow this line of thought then you really only need a CAT IV rated tester if you will be using it to test outside wiring that could be exposed to high current spikes such as lightning.
However, what happens if you are taking a measurement and a voltage spike comes over the line? Even if the tester you are using is rated correctly for the category of testing within which you are working, it will not protect you from a voltage spike. In fact, in this instance you would need the engineered safety features of a CAT IV 600V meter to protect you from harm.
So whilst it would be correct to say that you only need to choose a test meter for the highest category which you would be working in, it would also be correct to say that you wouldn’t want to be on the receiving end of a voltage spike if you didn’t have a CAT IV rated meter!
This is one of the areas where Klein Tools doesn’t leave anything to chance and the belt and braces approach which we have adopted means that all of our Tough Meters, including the 600A AC/DC TRMS Clamp Meter, are rated at CAT IV 600V which makes them the highest rated meters on the market.
A serious choice
Seasoned professionals know that when you are working with electricity you don’t leave anything to chance and good practice, such as using proper lock-out procedures are second nature. In the same way, using only well designed and well maintained test equipment should also be second nature.
You need to have confidence in your kit and be certain that it won’t let you down – and when I say let you down I don’t just mean that it will stop working at an inopportune moment. When sub-standard test equipment lets you down the best case scenario is that it can result in damage to equipment. The worst case scenario doesn’t bear thinking about.
So do look out for the safety features which should come as standard and check for the relevant symbols which prove that the equipment has been independently tested by a recognised testing organisation. These are all fairly standard when you buy a product from a brand that you can trust but you still need to check the Safety Category Rating because even products from reputable manufacturers will differ greatly. And finally, beware of wording which suggests that a product was tested to the required level of compliance – unless there is evidence in the form of a symbol from a recognised testing organisation, it very rarely is.
This feature was published in the March 2015 issue of Electrical Review. If you would like to commission a similar feature please contact Tracey Rushton-Thorpe.
