Everyone has budget concerns, but sometimes those concerns may lead to poor financial decisions. For example, consider two different digital multimeters (DMMs): A and B. DMM A is $100 less than DMM B, and they have the same measurement features. They are even the same accuracy and resolution. Which one should you buy?
The correct answer is DMM B, of course! But why spend the extra $100? Because DMM B has the safety features that help ensure you’ll be around a long time to enjoy that purchase.
The first thing you notice is that it has really nice test leads. They are thick and flexible, plus they have finger guards and shrouded terminals. But hey, you can buy a set of leads like that for DMM A and still save money, right? If you believe DMM A is just as safe as DMM B, even though the manufacturer of DMM A doesn’t get the test leads right, maybe you should check out that great deal that’s running on the Brooklyn Bridge.
What else might make DMM B stand apart from its cheap(er) counterpart? How about fusing on the current input? Granted, the fuse isn’t going to protect the meter from a major blunder, but it will protect against minor ones. You could live without this feature, but its presence indicates a meter designed to high safety standards.
The better DMM also has high-voltage protection in resistance mode. Although you know better than to connect a DMM to a power source while it’s set for resistance, mistakes do happen. Again, not a necessary feature, but it does indicate something about the overall safety design of the meter.
The meter also should have the marks of independent testing organizations on it. Those are necessary. Don’t buy a meter that doesn’t have these.
Finally, look at the terminal spacing. To make a meter safe requires insulation around its terminals inside the meter. That insulation takes up space, and so do the mechanically strong bosses in which those terminals are mounted. If the terminals are too close together, you’re probably looking at a counterfeit meter or a cheap knock-off that isn’t made to any standards.
How do you know if the terminals are “too” close? An easy way to check this is to compare the spacing with that of any high-quality name brand meter. If the cheap(er) meter has significantly less space, don’t buy it.