A Fluke insulation tester measures the electrical resistance of insulation, in the megohm range, to confirm that wiring, cables, motors and equipment are safely insulated and not at risk of leakage or breakdown. Installation testers go further, combining insulation testing with the other checks needed to verify a complete electrical installation.
If you commission, maintain or inspect electrical systems, these are core safety tools. This guide explains what they test, how megohm testing works, and how to choose between an insulation tester and a full multifunction installation tester.
What does an insulation tester actually test?
Insulation testing applies a known DC test voltage between conductors, or between a conductor and earth, and measures the resulting resistance. Good insulation gives a very high resistance, in megohms or higher. Low or falling resistance signals deteriorating insulation, moisture ingress, contamination or damage, often before it becomes a dangerous fault.
Typical uses include:
- Verifying cable and wiring insulation during installation and maintenance.
- Checking motor and transformer windings for insulation degradation.
- Periodic testing to catch deterioration before it causes failure or a safety hazard.
- Fault-finding when leakage or breakdown is suspected.
What is megohm testing?
Megohm testing is simply insulation resistance testing expressed in its usual unit, the megohm. Because healthy insulation has very high resistance, the readings are large, which is why these instruments are often called megohmmeters. The test voltage is selectable to suit the equipment under test, since you test at a voltage appropriate to the system's rating. Higher test voltages are used for higher-voltage equipment.
Insulation tester or installation tester, what is the difference?
This is the key choice.
- An insulation tester is focused on insulation resistance testing, often with continuity testing too. It is the right tool when insulation is what you need to verify.
- An installation tester (multifunction tester) does insulation and continuity but also the other tests required to verify a fixed electrical installation, such as earth loop impedance, RCD testing and more, in one instrument.
If your job is verifying complete installations to a wiring standard, a multifunction installation tester saves carrying several instruments. If you mainly check insulation on cables, motors or equipment, a dedicated insulation tester is lighter and simpler.
Which Fluke insulation and installation testers suit which job?
Insulation testing
The Fluke 1507 and Fluke 1503 are well-known handheld insulation resistance testers. They offer multiple test voltages for testing a range of equipment, in a portable form factor suited to field and maintenance work. They are a sensible default when insulation resistance is your main concern.
Full installation verification
The Fluke 1663 and Fluke 1664 FC are multifunction installation testers that combine the tests needed to verify electrical installations in a single unit, with the 1664 FC adding Fluke Connect features. These suit electricians and inspectors who certify installations and want one comprehensive instrument.
Browse what we carry on our installation testers category page, or see the full range under products. For everyday voltage, current and continuity checks alongside insulation work, our digital multimeters range complements these testers.
How do I choose the right one?
- What do you verify most? Insulation only points to a dedicated insulation tester; full installations point to a multifunction installation tester.
- What test voltages do you need? Match the instrument's selectable test voltages to the equipment you test.
- Do you need data logging or wireless? Models with Fluke Connect let you capture and share results, useful for reporting.
- What safety rating do you need? Choose a CAT rating appropriate to your working environment.
- Field or bench? Handheld units suit mobile maintenance; multifunction testers suit installation certification work.
Why electrical safety compliance depends on these tests
Insulation and installation testing is not optional box-ticking. It is how you demonstrate that an installation is safe to energise and stays safe over time. Documented test results support compliance with electrical safety requirements and give you defensible evidence that due diligence was done. Using a genuine, properly specified instrument is part of that assurance.
Buying genuine Fluke testers in Batam, Bintan and Singapore
Measurands is an authorised Fluke distributor serving engineers, contractors and procurement teams across Batam, Bintan and Singapore. Buying through an authorised channel means genuine product, the manufacturer's warranty, and local support rather than grey-market risk. See the local details on our Singapore page, and teams in Indonesia can start from our Batam page.
Tell us what you test and we will recommend the right Fluke insulation or installation tester for your work. Request a quote via our contact page and we will help you specify it correctly.
Frequently asked questions
What is a good insulation resistance reading?
Healthy insulation gives a very high resistance, typically in the megohm range or higher, while low or steadily falling readings indicate deterioration, moisture or contamination. The exact acceptable value depends on the equipment and the standard you test to, so compare against the relevant requirement for that system.
What is the difference between a Fluke insulation tester and an installation tester?
An insulation tester such as the Fluke 1507 or 1503 focuses on insulation resistance (and usually continuity). An installation tester such as the Fluke 1663 or 1664 FC adds the further tests needed to verify a complete electrical installation, like earth loop impedance and RCD testing, in one instrument.
What test voltage should I use for insulation testing?
You select a test voltage appropriate to the rating of the equipment under test, with higher-voltage equipment tested at higher voltages. Fluke insulation testers offer multiple selectable test voltages so you can match the test to the system, following the relevant standard or manufacturer guidance.
Need genuine Fluke, quoted fast?
Authorised distribution for Batam, Bintan & Singapore — reply within one business day.