Important Safety Information!

Using a multimeter - any multimeter - poses a level of risk that depends on many variables, and it's vitally important that the operator is fully able to assess that risk and act accordingly.

There are those who insist that no-one should use cheap multimeters under any circumstances, and while they have a point - and are usually speaking with the best of intentions - it's important to realise that not everyone can afford or justify buying an expensive multimeter. For some, electronics is a hobby rather than a professional occupation, so the funds needed to purchase a Fluke 87V or similar simply won't be available. In which case, can we be pragmatic? Before answering that, let's explore this issues:

So what's the problem with cheap multimeters?

Primarily, safety. Obviously, quality might well be an issue too, but at this end of the market, it's easy to accept that a cheap meter might not last forever or be the last word in accuracy - and the very cheapest ones can simply be regarded as disposable. While cheap tools can often be a false economy, you'd have to get through a lot of £10 multimeters before you start to regret not buying a £300 Fluke!

But the safety question is much more complicated and it's hard to do it full justice in such a short article, but the nub of this issue is this:

Cheap meters make unverified claims about their electrical safety.

For many years now, we have had the CAT rating system. This gives us a framework to identify the safety performance of a multimeter and assess its suitability for a certain task. But unfortunately, the scheme is self-declaring, and not all manufacturers have their meters independently tested and verified by testing bodies like TÜV and UL. The testing and certification process is complex and costly, so you simply won't find this at the cheap end of the market. In short, safety ratings on cheap multimeters are ficticious and often optimistic!

If this has piqued your interest, there is a lot of reading material out there. Perhaps a good place to start would be this note from Fluke, which gives a good overview of the CAT rating system, and describes how high-energy transients present a serious problem. This is a good overview video, also from Fluke. There are many more relevant resources freely available from Fluke in their Fluke News Plus area - all recommended reading. And just for balance, here's a similar overview from Keysight. Obviously, safety is part of the marketing machine for prominent manufacturers like these, which is understandable given how much effort they put into making safe multimeters, but please don't let that put you off - it all deserves careful consideration. However, if you'd prefer to get your information straight from the source, you need BS EN 61010-1:2010.

Professionals can't cut corners

If you are buying multimeters for work, you'd be mad to pick up a £10 meter from eBay! Ideally, you'd want something from a big brand that has its meters independently verified, but if budgets really are too tight for that, the £20 RS Pro RS14 is the minimum you should have. Is this meter any safer than a £10 eBay special? Perhaps. But even if they were completely equivalent, which of the two would look better to the Health and Safety Executive should the worst happen? Frankly, it's not worth the risk. Proper equipment is a cost of doing business.

But what about hobbyists?

But how is all this relevant to hobbyists, who are the target audience for this series of reviews? They won't be opening up industrial electrical cabinets containing high energy circuits, right? In theory, the worst that their DMMs will see is the insides of a bit of gear they are repairing or restoring, which is a CAT I scenario. But of course, if they own a meter that appears to have no problems measuring mains voltages on the bench, might they be tempted to use that meter when doing electrical work around their house? And if they did, would they realise that are they now in a CAT II or CAT III situation, where the maximum energy levels could be much, much higher?

As I said at the start, there are those who assert that no-one should risk using cheap multimeters. Unfortunately, this can lead - quite unintentionally - to division, where some hobbyists perceive feelings of snobbery and even derision from the pros, and instead of being encouraged to think more deeply about the very real safety issues, some go on to regard their cheap multimeters as a badge of honour. I see this happen on forums everywhere, and for that reason, I honestly don't want to preach about the issue. Instead, I want to reach out to those using cheap meters and encourage them - and everyone and anyone - to read up about multimeter safety. In recent years this subject has attracted a lot of attention and there is plenty of information out there that you might not have seen or considered before. Ultimately each person has to make up their own minds about this, but my aim here is for everyone to make it an informed decision.

It's not just the meter!

The final point I'd make is this: the most important part of electrical safety is you! No multimeter on earth can save an untrained or unthinking person from an accident. Paradoxically, there is actually a risk that a known-safe multimeter can result in a false sense of security! Every time you use a multimeter, there is risk that needs to be assessed, and a lot of the time, that risk is minimal to non-existent. However, this is not always the case, and thinking through the possible problems before attaching the test probes must become second-nature!

Disclaimers

I must emphasis that all meters reviewed here - unless explicitely stated otherwise - are for low energy use only. They should be absolutely fine for electronic bench work, but I'd recommend caution when using them to measure the mains voltage inside a bit of gear or even the HT voltage of a valve amplifier or radio. I would definitely not let them anywhere near the insides of mains fuse boxes (or other power distribution installations), or inductive loads like induction motors or similar.

Again, low energy electronics work only, in a hobbyist setting. My comments in these reviews must be taken in this context. All users must assess the risks for themselves, and no liability is assumed for loss or injury.

My reviews are for information only. I can't guarantee that other examples of these units will perform the same as the units I received. All units were purchased by me for the purposes of review (the only exception being the RS unit, as we use those at work) - no supplier or manufacturer has asked me to review their units or sent me free or discounted samples. If someone wants to sent me a unit for review, that's absolutely fine - I'll make that clear in the review, and you'll have to agree to my terms and conditions (email me if interested).