DurabilityĮlectricians often work in tight spaces, hot attics, or freezing conditions, in all types of weather. Most meters today are true RMS meters, but if you find one that isn’t, be aware that it will only provide averages and not exact readings. While some multimeters simply measure the average of the highs and lows of AC power, a true RMS meter provides accurate readings for the correct current level or voltage. Alternating current (AC) is composed of alternating high and low voltage in a sine wave form. Direct current (DC) is exactly what the name suggests: direct, unwavering current coming from a source. Root mean square (RMS) is a mathematical term that refers to the effective level of an electrical current. That means it needs to give true RMS readings. True RMSĪ good clamp meter needs to be precise and accurate. If the maximum current is 600 amps or more and you get a 500-amp clamp meter, you’re not only putting the meter at risk, you’re also taking a chance on giving yourself a shock. They might work, but if they don’t meet the safety standards, they may not be safe, properly grounded, shielded, or protected.Īlso know what kinds of electrical equipment you’re going to be testing. The UL 61010-1 standard is a safety standard for the manufacture and use of devices that measure, test, indicate, or record one or more electrical (and some physical) quantities.Ĭlamp meters that don’t meet the UL 61010-1 standard should be regarded as potentially dangerous. If you’ve ever been shocked by a live wire, you know it doesn’t take much to turn a mild shock into a life-threatening situation. Safety comes first in all things, and this is particularly true when dealing with electricity. There’s no universally agreed upon answer, and we’re not going to try to settle the issue, but for our purposes here we’ll use the terms multimeter and clamp meter. The terms multimeter, or meter, and multi-tester, or tester, are often used interchangeably, but some manufacturers argue that a tester is only used to confirm the presence or absence of an electrical signal whereas a meter is used to measure the strength of the electrical signal. multi-testerĪ quick note about terminology. Clamp meters are valuable because they can measure current without the system being off.