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A coworker once came up to me, air-door pressure switch in hand. As he passed it to me, he said," This switch is fried … it needs a replacement." This type of switch rarely goes bad. It just doesn't get that much use. So, I asked him what his meter read when he tested it.

Meters – An Electricians Best Friend

Steve Maurer, IME
A coworker once came up to me, air-door pressure switch in hand. As he passed it to me, he said," This switch is fried … it needs a replacement."

This type of switch rarely goes bad. It just doesn't get that much use. So, I asked him what his meter read when he tested it.

"Oh, I didn't test it. All the signs pointed to a failed switch."

I attached my test leads to the connections. The switch was, indeed, good. The problem was farther down the circuit. And to find the failed component would require the use of …

A meter.

A meter for almost every task imaginable
I'm a good electrician. And troubleshooting is one of my strong points. Yes, you can follow the operational sequence and get a good idea of where the problem lies.

But … you can't be sure without a meter.

And meters help you with more than just troubleshooting. Component or machine installs benefit from judicious use of metering devices.

One of my chores has been to wire in three-phase motors. Some relatively small, fractional HP motors … others up to and beyond 350 horsepower. The big motors drive machines like refrigeration compressors, both reciprocal and screw types.

Getting the rotation wrong can damage the compressor if run that way. And as you know, getting the direction right the first time is a roll of the dice.

But, there are meters that can roll the dice in your favor.

A phase/motor rotation tester lets you get it right … the first time, every time. It's a two part process:

  • Checking the rotary field direction and phasing on the source voltage
  • Determining the motor connections and winding rotation

Connecting the meter leads to the R, S, and T connections helps you determine the phasing on the incoming power. Most are A-B-C, but I've come across different phasing before.

Then you connect the meter to the motor leads. By giving the shaft a spin, the windings are checked for rotation. Once you found out how it should be wired for the proper direction, it's just a matter of marrying the motor to the power source.

Very, very cool.

Of course, there are other meters for other tasks … and multi-meters that handle several in one unit.
Meg meters, or meggers as we called them, checked for breaks in the insulation. That's definitely important after pulling a new run through a complex conduit configuration.

Earth ground resistance testers measure your ground rod resistance.

Long gone are the days when licking your finger and sticking it in a light socket to check for voltage presence was meter work (if your eyes lit up … power was present. Just kidding.)

There are so many things involved in electrical and electronic installation and troubleshooting that you just can't take a chance on guesswork.

A quality meter, designed for what you're testing, is the only way to be sure.
Photo courtesy of IDEAL Industries
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