Habotest HT107D/E - socket tester

[Habotest HT107D in hand]

Must-have tool!

[Italian version here]

Product name: Habotest HT107D - socket tester and voltmeter
Manufacturer: Habotest - China
Cost: ±15$/€
Reviewer: Lucio Cadeddu - TNT Italy
Reviewed: February, 2022


Any audiophile worth his weight in exotic mains plugs and cords knows that electricity plays a key role in HiFi system performance. There are many things that can go wrong: insufficient or excessive voltage, reversed live/neutral connections, missing or not properly working earth connection and leakage currents. Generally, since electricity kills, it is a good idea to have a trained technician verify your mains distribution at home. Still, there exists a safe and easy checklist everyone can investigate. And this is why I'm testing a socket...tester.

There are many different socket testers in the market, some are very basic and just tell you whether the cables are connected in the right way or not, but we audiophiles need more, as usual. I've choosen this Habotest HT107D socket tester, which is labelled as “Pro”, whatever this might imply. Habotest is a Chinese company, located in Dongguan, which manufactures many different testers, so it is reassuring to know this is their sole business. They do not manufacture other electronic components, just testers. They also manufacture different socket testers. The one I've decided to test is the model HT107D which is the most complete of the catalogue, if I understand well. It seems only EU plug and UK plug standard are available. The UK plug version is the HT107E.

[Habotest HT107D]
The HT107D at work. Please note the 230V perfect voltage at home! N-E voltage oscillates between 1 and 2 V

The HT107D delivers various useful information about the health status of your mains at home. First of all...


Insufficient or excessive voltage might be dangerous or lead to components not working properly. Consider that - generally - voltage might vary in a range of ±10% tolerance (here in Italy, while it's 230 volts -6%, +10% in UK and Australia, and 120 V ±5% in USA and Canada, for example) so please don't be too picky about it. The HT107D has a backlit display that indicates real-time voltage at your mains. If you check voltage at various times throughtout the day you can have a gross estimate of voltage fluctuations, if any.

Correct wiring/phase

Another audiophile concern is correct wiring and, hence, phase. Incorrectly wired sockets are not uncommon. Are the live/hot and neutral wires reversed? Are the neutral and ground/earth wires reversed or shorted?

Many components aren't sensitive to polarity, but sensitive electronic loads such as computer equipment, instrumentation and exotic HiFi components do care about a clean ground (i.e. a ground with no voltage and no-load currents on it). When everything is OK the socket tester's backlit display glows green, orange/red otherwise. Not only that, there are three red leds that indicate what's wrong with your socket. The different options can be read in the table below. To fix a problem, ask a professional, unless you know exactly what to do. A missing ground warning should be something to check immediately, and not only for audiophile purposes. Consider that many HiFi components do not use the ground connectors in the plug, since they have been designed with a so-called double-insulation (Class II). A missing ground/earth connection shouldn't be a problem in this case, but will certainly need fixing for other components that do require an earth!

[Habotest HT107D]


The job of a RCD is to immediately interrupt the circuit in the event of a fault. For this, there are a variety of designs. Such devices with a trip value of 300 mA are frequently used for protection against fires, and those with 30 mA for human contact (and this is the one we have at home, generally). It might be different depending on the country you live in. For example, in the USA there is no RCD, but GFCI (Ground Fault Circuit Interrupter) instead, which trips at lower currents. The HT107D tester checks whether your RCD circuit is good or not. There's a switch you might use to verify if the RCD is working correctly (just press it for more than 2 seconds). Of course the test makes the RCD kick in, verify that you have nothing connected to the mains while performing the test. The display shows the current above which the RCD kicks in.

Leakage current (N-E voltage or stray voltage)

Another good information the tester gives you is the presence of leakage current between neutral and ground. The term leakage current refers to current that flows to ground in a properly operating circuit or to an external conductive component. In other words, the current does not return through the neutral conductor. By measuring live-neutral voltage, neutral-ground voltage and live-ground voltage you are ready to answering these questions:

These three measurements, all taken quickly at one outlet, let you know what's going on/wrong. Theorically, the voltage between neutral and earth (N-E) should be 0 Volts, but in real life conditions it is considered acceptable if it stays below 10V. The lower the better, of course. This highly depends on the mains distribution system, on eventual capacitive coupling of the wires and on many other factors. In different distribution systems (called phase-phase) this measure could be very different. Ask a local technician about the mains distribution system in your area.

Remark. If you look at some pics of the HT107D you can find on the web, it seems it should display mains frequency as well. Mine does not. Instead of frequency, it displays RCD current. Perhaps the frequency is displayed by a different version of the device, frankly I do not know. In any case, there's nothing you can do about wrong mains frequency, as this depends only on the power company and small fluctuations are allowed, as synchronous turntable owners know well!


Globally, this socket tester is sufficiently accurate, easy to use and inexpensive. Even someone with little or no knowledge in this field can use it without problems. In case of trouble there's a complete manual (in English) that explains its features and how to understand the findings. The packaging is very basic, so I suggest that you ask the shipper/seller for a strongly padded box or envelope. One of the devices I ordered arrived at home completely destroyed. You can get a partial refund, but it's a waste of time, most of all.


Usual web stores have these testers in stock. Aliexpress and Amazon or Ebay are the places where to search for this device.

Tech specs


This Habotest HT107D is quite a useful device and lets you understand easily what's going on, even if you're not a trained technician. Just insert it into the socket you wish to test and you're done! It makes no use of batteries and is 100% safe to handle. Another must-have, I'd say.

DISCLAIMER. TNT-Audio is a 100% independent magazine that neither accepts advertising from companies nor requires readers to register or pay for subscriptions. After publication of reviews, the authors do not retain samples other than on long-term loan for further evaluation or comparison with later-received gear. Hence, all contents are written free of any “editorial” or “advertising” influence, and all reviews in this publication, positive or negative, reflect the independent opinions of their respective authors. TNT-Audio will publish all manufacturer responses, subject to the reviewer”s right to reply in turn.

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