My father, a contractor of almost forty years had a hammer he called “Ol’ Reliable.” He may not be very creative, but it was most certainly old and presumably reliable. The hammer endured over 30 years of use and stayed with him in spite of his habit to misplace tools. They were inseparable.. That is, of course, until a birthday gift from a certain son guilted him into using a sleek, new hammer which would eventually replace that prehistoric mallet. When it comes to your old reliable clamp or multimeter, tools with significantly more functionality than a hammer, you may have much more to gain than my father and his now splinter-free hands. There may be safety, application, and functionality implications, just to name a few.
The primary reason why you should consider going with a new meter is your own safety. Electrical testing can be extremely dangerous, especially if you are reckless or unknowledgeable. You want to be sure that you know what your meter can and cannot safely measure. One major safety concern has to do with overvoltage and transients. You may not be able to avoid transient spikes but when coupled with a powerful current and a meter that cannot take the added load, damage to your meter and ultimately your personal safety are possible threats to be taken seriously.
IEC CAT ratings are the easiest way to know where your meter belongs. The higher the CAT rating the closer you can measure to a utility connection. Indoor electronics with built-in spike protection will likely have the lowest, CAT I rating, whereas an outdoor installation with a connection to the utility pole will have the highest, CAT IV safety rating. Many meters out there are old enough to have not been given a rating at all. If this is your meter you might be best served trading up to ensure your own safety. Check that your meter has a sufficient rating under the IEC 61010-1 standard for your measurement needs.
Juggling an assortment of tools on the work site can be tedious, annoying, and sometimes inefficient. Typically, older meters will have fewer measurements and ranges forcing you to buy additional meters to service your growing measurement needs. If you’re buying a meter to add to your tool bag it might be easier to get one that centralizes many of those other functions in one meter, saving you time on the job and possibly a little bit of money.
Similar to application, the functionality of a new meter might be a deciding factor. More and more meters are offering memory space and datalogging; some will graph the measurements, and many are able to send measurements to other meters or upload to a computer for analysis. These functions and more make the instrument versatile and your workflow significantly more efficient.
Older meters are often averaging meters which can deliver measurements that are inaccurate –35-40% under or as much as 8-10% over. True RMS meters are not linear averaging meters; they use a root mean square formula in order to provide more accurate readings of distorted wave forms. If you’re measuring distorted (non-sinusoidal) waveforms you’ll want to do so with a True RMS meter.
Lastly, new meter functionality may include LoZ and low pass filters which older meters are unlikely to have. LoZ prevents false readings caused by ghost voltages and LPF (low pass filter) is for the accurate measurement of variable frequency drive signals – two functions to consider and look out for.
Safety, growing measurement needs, and functionality are three areas to consider when thinking of replacing or buying a new meter. Let’s just hope it doesn’t take that birthday present guilt to surpass your sentiment for Ol’Reliable.