Do I really need that?

2 April 2020


With so much uncertainty in the world right now, nothing feels normal. But one thing you can always count on is this blog – every week.

Since we’re committed to helping you keep the power on – now and always – we wanted to give a quick shout out to all of the men and women keeping our power on throughout this crisis.

In New York, electric grid operators have taken drastic measures to keep the power on – sequestering away from their families and friends, with no outside contact for the foreseeable future. It’s anticipated that similar emergency measures may spread to utilities across the United States.

We can’t imagine how difficult this is, but we are immensely grateful for your sacrifice.

Today, we’re talking about insulation testers. There are a lot of options, so it can be tempting to just grab and go. While that’s a great approach for choosing a snack from your pantry, it’s not the best method for choosing an insulation tester for your application.

It’s worth your while to take a minute (or ten), make a cup of coffee (or a whole pot), sit-down, and think about exactly what you want to accomplish with your insulation tester. You should be using a tester that maximizes effectiveness without wasting money (and time) on unnecessary features and functions.

If you don’t need a feature – don’t pay for it.

At the same time, if there’s a feature that could help you do your job quicker, you may be wasting time without it.

So, today it’s all about the money, really. We’re going to help you decide if you really, truly need to spend more to get more, based on your specific applications.  

By the way, we’ve already chatted about choosing an insulation tester, as you may remember. We looked at many features – from test voltage to power source to test ranges.

Today’s blog differs, since we’re just talking specifically about whether you need a high-end tester or one that’s more basic or something in between – based on the included features and what you’re planning to do with it. Got it?

Do I really need that?

Today’s guiding question. It’s also the question I try to ask myself whenever I go shopping. The answer’s usually no. Do I listen to that answer? Also, usually no.

Anyways, we’re going to break this up into smaller, more manageable questions though, so you don’t ignore your own answers – like I do.

By the way, we should probably mention how an insulation tester actually works – in case you don’t know. It’s simple though. It just applies a voltage, measures the resulting “leakage” current of the insulation, and calculates the resistance based on Ohm’s Law.

Do I need a high range tester?

The higher the range of the tester, the smaller the current it is able to measure. If the current goes over that range, the limit of sensitivity has been hit and the tester is just going to pop-up an “overrange” message. This is usually indicated by an “infinity” symbol or “greater than # ohms” – depending on the tester you’re using. It’s simply telling you that the actual measurement is greater than what the tester is capable of reading.

Now, here’s where you need to ask yourself more questions.

Am I doing pass/fail testing?

If yes – then it’s okay and probably easier, if you’re just looking for that “infinity” reading. Applications like commissioning new equipment or proofing a job would usually fall into this category, and a basic, inexpensive tester with a limited range – to a few thousand megohms – is perfect for you. In these circumstances, having an extended range is essentially overkill and just makes things more complicated.

Am I doing ongoing electrical maintenance?

If yes – an economical tester is probably a poor choice for you. Measuring insulation resistance is not simply a one and done test, but rather it is a repeated, standardized test that’s done again and again, since insulation deteriorates gradually and steadily over time.

If you can afford to record an actual number, rather than just a “pass” reading when you’re commissioning a new piece of equipment, you can use that value as a base for comparison. Over time, if the readings are high, but falling sharply, this could indicate that the operating environment is hostile – perhaps with dirt, moisture, heat, corrosive fumes, etc. – and give you time to fix it without significant impacts to production.

On the other hand, if you are working with a tester that’s simply go/no-go, there will be no indication that something is wrong, and you’ll have a false blanket of security. In these circumstances, a “pass” result will just tell you that the equipment is fine for now, but who knows how long that good fortune will last? Not you!

Okay, now let’s look at continuity – the opposite of insulation.

With a continuity test, you’re looking to make sure that your circuit is isolated, and all of the connections are continuous. Simple enough, right? Many times, a tester will just have a “buzzer” function, which sounds a tone when continuity is achieved.

Now, here’s the question (or questions) to ask yourself.

What environment am I working in?

Am I working in a dim environment where it’s hard to see? If so, you’re probably going to love the buzzer function, since the display will be hard to see.

Am I just doing repetitive sign-off checks? If yes – again – you’ll just want to be able to move the probes from circuit to circuit as quickly as possible and listen for the tone. The actual number probably doesn’t matter to you, so this feature would be a huge time saver and convenience.

Am I proofing a large commercial panel? If you are, it could be extremely frustrating to have to wait the one to two seconds for the buzzer to sound each time. It doesn’t sound like a lot, and at first it might not seem terrible, but over time those pauses add up and your frustration could lead to error if you’re trying to sign off a large panel.

Okay, are you sick of these questions yet?

Hopefully, you got the point though. Sometimes less is more. Spending more doesn’t necessarily make your job easier. When it comes to choosing an instrument, choose one that fits your specific job, skill-level, and application, and ask yourself the aforementioned questions – please!

Still have questions? Download our complete guide to insulation resistance testing.