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For a one meter long test lead from China you pay € 1.40, while the same kind of cables from brands such as Hirschmann and Voltcraft are much more expensive. Are those cheap Chinese leads so much worse in quality? We investigated. |
4 mm banana to 4 mm banana, 1 m length
Three suppliers compared
The test leads you use most often are leads with a male 4 mm banana connector on both sides. These cables are available in various sizes, but one meter is a standard length supplied by almost all manufacturers. That is why we have selected them for our TEST.
Supplier 1: Daniu
The Chinese brand Daniu delivers under the code P1036 a set of ten such measuring leads in 2 x 5 colors for a price of € 13.93, so for € 1.40 each. All well-known Chinese mail order companies such as Banggood and AliExpress have these types of leads in the program.
As with almost all Chinese products, no attention is paid to the way the cables are packed before shipment. This means in this case that the ten cables are packed in a far too small plastic bag as if it were a plate of spaghetti. Fortunately, little can damage cables, so this method of transport is not a problem.
Unfortunately there is not a lot of technical information about these leads:
- Cable material: PVC
- Cable diameter: 3.7 mm
- Plug diameter at thickest point: 4.3 mm
- Conductor surface: 1.4 mm²
- Maximum current: 15 A
- Maximum voltage: 1,000 V
That 1,000 V must of course be a joke from the manufacturer. However, the cables are definitely suitable for connecting to the 230 V mains. You'll probably never find higher voltages in your hobby lab.
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| Five of the ten measuring leads in the Daniu package. (© Banggood) |
This house brand of Conrad Electronic delivers under code 108608 a measuring lead that looks almost identical to that of Daniu. Only the price is slightly different: € 5.50 for one cable. This test lead is available in the five colors that Daniu also has. For ten such cables you will pay € 55.00, or almost four times more than for the Daniu cables.
Unfortunately, there are few technical data of these cables can be found:
- Cable material: PVC
- Conductor surface: 1 mm²
- Temperature range: 0 °C ~ +80 °C
- Measuring category: CAT 1
The official description of CAT 1 is: 'Suitable for measurement on circuits that have no direct connection to the mains, e.g. flashlights, cameras, mobile phones and electrical and electronic equipment in cars'. According to this description you cannot use the Voltcraft cables to connect to the mains! However, we do not believe that there is a one electronics hobbyist who complies with this directive.
Supplier 3: Hirschmann
This well-known cable manufacturer supplies an identical cable under type number MLN100/1 which costs € 6.78 each. So for ten pieces you have to pay almost seventy euros! This cable is also available in the five standard colors.
The manufacturer supplies a data sheet of this cable, from which we get the data below:
- Cable material: silicone, very flexible
- Cable diameter: 3.7 mm
- Wire surface: 1.0 mm²
- Wire composition: 259 x 0.07 mm diameter
- Maximum current: 16 A
- Maximum voltage: 30 Vac, 60 Vdc
- Contact resistance: 22 mΩ
- Measuring category: CAT 1
That 259 wires with a diameter of 0.07 mm fit into a surface area of 1.0 mm² doesn't seem very credible at first, but calculate it and you'll see that it really is possible.
This Hirschmann cable is 'lötkolbenbeständig', which means that you can hold your hot soldering iron against the cable without melting the insulation, which happens with PVC cables. In addition, there is a different colour under the very thin top layer, so you get an optical warning if something is wrong with the insulation.
First conclusion
From the limited data provided by the manufacturers, you can deduce that Hirschmann pays much more attention to its cables than the other two suppliers. In terms of appearance and ease of use, this cable is definitely better. But whether this justifies the enormous price difference for you as a hobby technician?
An optical comparison: the banana plugs
Not much difference to discover
Clearly, Hirschmann's test leads are superior in terms of choice of material for the cable itself. But are there any other qualitative differences that explain the price difference? We will look at the banana plugs. Gold plated, silver plated, nickel plated? In the photo below, we have compared the three plugs. There is no difference to discover. The three leads are equipped with a so-called 'lamella plugs'. The lamellae ensure good electrical contact in the female banana socket and good mechanical strength of the connection. All three plugs are made of nickel-plated copper.
According to Hirschmann's data sheet, the lamellae of the plug are made of beryllium copper. This is an alloy of copper with 0.5 % to 3.0 % beryllium. This alloy has very high mechanical values and is suitable for use at high temperatures where wear and tear can play an important role. Does not seem necessary in the hobby lab environment!
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| The three plugs are compared. (© 2020 Jos Verstraten) |
What is striking is that the plugs of Daniu and Voltcraft are much more touch safe than those of Hirschmann. With the latter plugs, the chance of your finger slipping off the isolated part of the plug and making contact with the metal pin is much greater.
The internal resistance
The only measurable parameter
Of all the parameters of such a test lead, we can only measure the internal resistance. This is of course the most important parameter. But the manufacturers, except Hirschmann, do not mention it. The Hirschmann lead has a 'contact resistance' of maximum 22 mΩ. What is meant by this is unclear. Is that the contact resistance of one plug in one socket? Or is it the cable's own resistance?
The parameter of practical importance is the total resistance of the test lead, i.e. from one banana socket to another. We measured this from the ten cables supplied by Daniu.
How do you measure resistors in the mΩ range?
This is not done directly with your multimeter, because it is completely unreliable when measuring such low resistors. The only method is to use the Kelvin technique. A large, well-known direct current flows through the resistor. The voltage drop caused by this current across the resistor can be measured with your multimeter. Although this voltage is in the mV range, most multimeters can accurately measure such small DC voltages.
The measurement setup
In the figure below you can see a sketch of the measuring setup we made for measuring the resistance of the Daniu test leads. A lab power supply, set as a constant current source, supplies a direct current of 7.00 A through the two banana sockets and the lead to be tested. A digital multimeter is connected to the same sockets, set to a range of 999.9 mV.
From ohm's law you can easily calculate the total resistance of the test lead: divide the voltage drop in mV by 7 and you get the cable resistance in mΩ.
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| This way you can accurately measure the low resistance of a test lead. (© 2020 Jos Verstraten) |
In the table below we have summarized the results of our test. As can be seen, all ten leads have approximately the same internal resistance. The average value is 29.05 mΩ. That's obviously a very good value.
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| Measurement of the internal resistance of the ten Daniu test leads. (© 2020 Jos Verstraten) |
Our conclusion from this test
Although we immediately admit that we cannot test most of the parameters of such measurement leads, we still dare to draw the conclusion that you, as a hobby electronics enthusiast, do not go wrong with these cheap Chinese cables and do not have to spend extra money on their European counterparts. Apparently also here you have to pay a lot of extra for an imprint with the logo of a famous brand on the product.
DANIU P1036 10Pcs Banana-to-Banana TestCable
