Update: recently Fluke and Megger have launched new generations of Multifunction Testers and we published a new article, that you can find here:
The two most popular brands in the UK for 17th Edition multifunction testers are Fluke and Megger, but how do you decide which one to go for? If you’ve not had the chance to actually use the products, making the decision can be difficult. There are a number of pros and cons to each model, with various users championing one particular brand over another.
This article looks at the key differences with the products, addresses some issues that have been raised and includes information from our service engineers, who calibrate these on a daily basis.
Ease of Use
Megger have designed their tester with two colour-coded dials on the front panel, enabling you to quickly select the test and settings you require. In addition the Megger tester has a device across the lead inputs to protect against accidentally connecting the wrong leads and includes a test button on both the left and right side, making it easier to use for both right and left handed people.
By contrast, the Fluke product has a simple dial to select the required test, with a function button to choose the test setting to use. The Fluke tester also checks lead connections and will indicate incorrect connections on the display.
Whilst it is really down to personal opinion, we feel that the Megger is likely to be easier to navigate than the Fluke.
What 17th Edition Tests Do They Carry Out?
Each of the two models will carry out the standard 17th Edition tests, however it is important to note that the low end models (Fluke 1651B & Megger MFT1710) won’t give you the auto RCD test, which many installers prefer.
When it comes to the tests, both the Fluke and the Megger are similar in what they offer, however there are some differences. Each tester offers the following tests as standard:
- Voltage Test: 500V
- Insulation Test: 250V, 500V & 1000V
- Continuity Test
- Non Trip Earth Loop Test
- High Current Earth Loop Test
- PFC / PSC Test
- RCD Trip Time Test
- RCD Auto Test (Not Fluke 1651B or Megger MFT1710)
- RCD Ramp Test (Not Fluke 1651B or Megger MFT1710)
- Phase Rotation (Not Fluke 1651B or Megger MFT1710)
Some of the testers offer unique test functions, such as the two wire non-trip loop test, which is only available on the Megger testers, as is the earth leakage function, which comes as standard with the Megger MFT1720 & MFT1730, although this does require an optional clamp accessory.
The Fluke 1654B is unique in that it will give a 0.001Ω resolution on the high current loop test.
On a final note, the Megger MFT1730 and Fluke 1654B will also test a full range of RCD types, including selective and B type RCDs, as well as having an option to carry out an earth ground resistance test.
For a full breakdown of the test options available, please download our comparison chart.
Loop Test Accuracy
Whilst the number of test functions is influential when making a buying decision, it is also important to understand the specified accuracy of the testers. One of the most common questions with any 17th Edition multifunction tester is about differing readings on a non-trip loop test. Compare several different multifunction testers side-by-side and inevitably you will get different readings, the question is why? And are the results reliable?
Firstly it’s important to understand that every manufacturer has their own non-trip technology, this means that the readings are taken at what averages out to be a low current to avoid tripping RCDs. Typically a number of readings are taken during the test and an average reading is then displayed on-screen, which is the one you would write down.
These different approaches will influence the end result, which is why often you will see differing readings. Another problem is noise on the line, because anything that is connected to the circuit at the time of test may cause a problem. This may lead to the tester taking longer to carry out the test or indicating it cannot give a reading due to excessive noise.
The accuracy of the non-trip loop tests for both manufacturers are detailed below:
Fluke: +/- (3%, + 6 digits)
Megger: +/- 5%, +/- 0.05Ω +/- Noise Margin
So, with an applied value of 1Ω, you could get any result between the following and the tester would be working within specification:
Fluke: 0.91Ω to 1.09Ω
Megger: 0.90Ω to 1.10Ω (+ Noise Margin, which is unknown).
Both testers performed well during testing in our service department, with satisfactory and repeatable results. However it is worth noting that these are calibration tests, carried out under laboratory conditions. In reality both testers are subject to noise and both accuracies are perfectly acceptable for 17th Edition testing.
Other factors can also influence your earth loop readings, such as the condition and design of your test leads, which we will look at now.
What About the Test Leads?
For many years, one of the big complaints about the Fluke testers was the leads. The older models had a Robin branded lead with a standard fuse housing. Over time, with constant changing between probes and croc clips, the screw thread could wear down and the fuse would become loose in the housing, resulting in fluctuating readings.
Around 2 years ago, Fluke completely redesigned their test leads, making the fuse holder more robust and as such the leads are now more rugged and a lot more reliable. This improvement has definitely restored the confidence in the testers, however the cost of replacing the full 3 way set is now over £100 including VAT. Our service engineers have seen a vast improvement and feel the Fluke leads are better.
Megger supply their testers with a set of standard leads, and a handy accessory that adapts the red probe tip to allow testing of small components or at hard to access points. There is a fused lead set available as an option, with the price at around £55 + VAT. It’s worth noting that the Megger test leads are not compatible with standard R2 socket adaptors, due to the banana plug on the test probe not being long enough.
From left to right: Fluke TL165X/UK, Megger 1001-991 (standard leadset supplied with all Megger MFTs), Megger 1001-975 Optional Fused Leads
Both ranges are supplied with a remote test probe (with the exception of the Fluke 1651B), making testing easier and quicker, and a mains test lead for testing directly at the socket.
Each MFT has a lead null function and it will remember the value, even when the tester has been turned off, so it is important to re-null leads if switching to and from a 50m wander lead for example. The Fluke testers also come with a unique “Zero Adaptor” for quick nulling of the three way leads and the mains test lead.
Are the Downloading Versions Worth the Extra Money?
If you are doing a lot of Electrical Installation Condition Reporting, then the downloading features will save you a lot of time. Both Fluke and Megger have this feature in their top end models (Fluke 1653B, Fluke 1654B & Megger MFT1730) and you can purchase all of them with a comprehensive software package.
In addition, the downloading versions from both manufacturers are the only ones that include the ground resistance test, so if you want this feature then the downloaders are your only choice.
The Fluke allows you to store information such as the board and circuit number, with the ability to tell the tester which test is being carried out. This means that when the information is downloaded to the software, the results are automatically assigned to the relevant part of the certificate. The Fluke software will print either plain paper certificates or onto NICEIC certificates. One of the downsides of the Fluke downloader is the IR port, which has been reported as unstable at times. It would be good to see a future model with a USB port instead.
Megger’s software is a bit more comprehensive as it has a wider range of certificates available and it will print onto NICEIC, ELECSA & SELECT certificates. The Megger also offers the option of Bluetooth connectivity, so results can be sent directly to a laptop or PDA for auto-filling of the test certificate onsite, alternatively you can store the results for download via USB. The Bluetooth connection can be temperamental, so it may be easier to store results for later download.
Value for Money
It comes down to what you are looking for in your MFT. Both brands have a strong presence in the industry and are well respected for quality and reliability. Each manufacturer backs up their testers with a 3 year warranty and Fluke will even cover the test leads for the first year too.
On paper, both brands offer pretty much the same tests, however there are unique features across the ranges, so consider what you want from your tester and whether any of the additional tests, such as ground resistance testing, may be required in the future.
Generally the Fluke equivalents are in the region of £100 less than their Megger counterparts, but that does not necessarily mean a compromise on quality. Also, when you look at the individual tests and features, the Megger testers do offer a little more, which justifies the price difference.
If you are considering the purchase of a new multifunction tester, have a look at our comparison between these two and decide which one will best suit your requirements, with the design and features that matter to you.
