Absolute Best MultiMeter Test Leads - Very Low Resistance?

[nytefog]

Hello,

I’m in search of the absolute best multimeter test lead available that have the lowest possible measurable resistance available.

The fluke TL175 test leads I normally use for everyday testing always seem to have 0.5 ohm resistance reading. I’ve tired cleaning the test leads and meter connection ports but it makes little difference.  I have even tested a set of brand new fluke TL175 lead and the have about the same resistance.  I tested them both on a Fluke 87v and 289.

I recently bought some Probe Master 8100 test lead which definitely have a much lower resistance, which I can’t remember off the top of my head now, and I am happy I got them but hoping there might be test leads that are a step above Probe masters or multiple steps above them!

Does anyone happen to know of any better meter test leads to that have almost no measurable resistance? I know they will always have some resistance of course.  I know this is probably not a common question people ask. I know I should have a 4-wire kelvin milliohm meter for measuring very low resistance reading, but i really can’t justify the cost of such a meter at this time.  I would really love to get a Gossen Metrawatt Metrahit IM Tech BT multimeter (M272S) but that is definitely out of the question as of this time.

I love to hear any suggestions.  I’m sure others are much more knowledgeable about this subject than I am.

I appreciate any and all feedback!

[Whales]

Is the 0.5R only from the leads or noticeably from the multimeter itself (eg input fuse)?  It might be worth checking with a big metal shunt across the input jacks.

[bdunham7]

I recently bought some Probe Master 8100 test lead which definitely have a much lower resistance, which I can’t remember off the top of my head now, and I am happy I got them but hoping there might be test leads that are a step above Probe masters or multiple steps above them!

If you have the 8000-series with the fixed probe tips (and threads) then the body of those tips is stainless steel which has higher resistance--although the gold plating helps.  If you have the 8150 retractable "pogo-pin" style, then you probably have one of the lowest resistance probes that I know of, with the drawback that the resistance varies a bit.  There's only so much you can do with a 2 wire system.  There are almost-4-wire systems that have 4 banana plugs or the equivalent, dual conductors going to each tip and then a low-resistance tip.  I tried making some using ProbeMaster 8000-series parts, but the resistance of the tip body was enough to make it not as good as it needed to be.  What multimeter or ohmmeter are you using?

[tggzzz]

So you think low resistance leads will solve your problem, but you haven't explicitly stated the problem and your objectives (including numbers, not adjectives). For an example of how that can be important, see
https://entertaininghacks.wordpress.com/library-2/good-questions-pique-our-interest-and-dont-waste-our-time-2/

Errors in measuring resistors below, say, 10ohms can have many sources of error, including variable contact resistance, I²R heating causing resistance changes, thermoelectric (Seebeck) voltages.

If none of those are significant, you could do a differential resistance measurement, subtracting out the lead resistance. Alternatively, use a Wheatstone bridge.

[The Electrician]

Just short the probe tips together while in ohms mode.  Subtract that value from any measurements you make of very low resistance components.

Some multimeters have the ability to automatically subtract the lead resistance.  My Fluke 187 has a button labeled "REL" (relative).  I just short the probe tips, press "REL", and the display then shows "0.000".  Measurements I then make will have the lead resistance subtracted from the measurement.

[tooki]

Hello,

I’m in search of the absolute best multimeter test lead available that have the lowest possible measurable resistance available.

The fluke TL175 test leads I normally use for everyday testing always seem to have 0.5 ohm resistance reading. I’ve tired cleaning the test leads and meter connection ports but it makes little difference.  I have even tested a set of brand new fluke TL175 lead and the have about the same resistance.  I tested them both on a Fluke 87v and 289.

I recently bought some Probe Master 8100 test lead which definitely have a much lower resistance, which I can’t remember off the top of my head now, and I am happy I got them but hoping there might be test leads that are a step above Probe masters or multiple steps above them!

Does anyone happen to know of any better meter test leads to that have almost no measurable resistance? I know they will always have some resistance of course.  I know this is probably not a common question people ask. I know I should have a 4-wire kelvin milliohm meter for measuring very low resistance reading, but i really can’t justify the cost of such a meter at this time.  I would really love to get a Gossen Metrawatt Metrahit IM Tech BT multimeter (M272S) but that is definitely out of the question as of this time.

I love to hear any suggestions.  I’m sure others are much more knowledgeable about this subject than I am.

I appreciate any and all feedback!

What do you expect to gain from further improving the leads? For voltage measurements it doesn’t matter. For very low resistance measurements you need 4-wire measurement anyway (and then the lead resistance doesn’t matter). It doesn’t really matter for current. So…?

[alm]

I agree with tooki.

f you want to measure low resistance, this is easy to improvise. Use a bench power supply to source a constant current, like 100 mA. Set the voltage limit low enough so it won't cause excessive dissipation in the resistor. Run this current through the resistor, and with different leads connect a DMM across the resistor and measure the voltage. Use either the power supply's built-in meter or a second DMM to measure current. Then calculate resistance using Ohm's law. This pretty close to what an ohmmeter is doing in four wire mode, except less convenient.

[bdunham7]

What do you expect to gain from further improving the leads? For voltage measurements it doesn’t matter. For very low resistance measurements you need 4-wire measurement anyway (and then the lead resistance doesn’t matter). It doesn’t really matter for current. So…?

Sometimes you just want reasonably decent and reliable low resistance readings but don't need many decimal places.  Kelvin measurements can be inconvenient.  The key really is reliable, consistent overall test lead circuit resistance, including the contact resistance.  Obviously low is also better, but consistency comes first.  There can be a huge difference between ordinary test leads in this regard even among versions that work just fine in other situations.  Some of the nickel-plated (or whatever they are) Fluke leads are terrible for this, even though they work very well in other situations. 

OTOH, I have ProbeMaster 8150 leads with the CuBe "pogo-pin" ends that I use with my old 4.5 digit Nixie-tube DMM and even though its lowest resistance range is 1k, it fairly reliably reads out low resistances to within 1 count (0.1R).  So IMO pursuing better two-lead solutions is definitely worth it--to a point.  The ultimate quasi-two-lead solution is Fluke's 2X4W system, but there are only three meters that use that and two are discontinued.

[tooki]

What do you expect to gain from further improving the leads? For voltage measurements it doesn’t matter. For very low resistance measurements you need 4-wire measurement anyway (and then the lead resistance doesn’t matter). It doesn’t really matter for current. So…?

Sometimes you just want reasonably decent and reliable low resistance readings but don't need many decimal places.  Kelvin measurements can be inconvenient.  The key really is reliable, consistent overall test lead circuit resistance, including the contact resistance.  Obviously low is also better, but consistency comes first.  There can be a huge difference between ordinary test leads in this regard even among versions that work just fine in other situations.  Some of the nickel-plated (or whatever they are) Fluke leads are terrible for this, even though they work very well in other situations. 

OTOH, I have ProbeMaster 8150 leads with the CuBe "pogo-pin" ends that I use with my old 4.5 digit Nixie-tube DMM and even though its lowest resistance range is 1k, it fairly reliably reads out low resistances to within 1 count (0.1R).  So IMO pursuing better two-lead solutions is definitely worth it--to a point.  The ultimate quasi-two-lead solution is Fluke's 2X4W system, but there are only three meters that use that and two are discontinued.

Yeah I understand all that, but I asked what they expect to gain by further improving the leads, i.e. beyond the already-superb Probe Master 8100 they already have?

[bdunham7]

Yeah I understand all that, but I asked what they expect to gain by further improving the leads, i.e. beyond the already-superb Probe Master 8100 they already have?

I don't see an 8100 model, so I wanted to be clear that the pogo pin style was what he has.  If not, there is clear improvement to be had by going pogo.

As for further improvement, as I mentioned sometimes Kelvin sensing is impractical and the Fluke 2X4W system gives you the convenience of normal probes with much better performance, perhaps 100X better than a typical 2W setup. You can also get a probe set from Pomona the does something similar with almost any 4W-ohms meter.  I tried making my own, but was unable to source a decent tip end and the ProbeMaster SS tips don't work well enough.  If the OP has a compelling need to do low-resistance measurements with probes, than this is the way to go.

[mqsaharan]

Hi nytefog,
I haven't read the whole thread, somebody may have mentioned it already; For lowest resistance and worst probe end, because it is blunt, get Uni Trend's UT-L21 probes. They are, of course cheap, have some type of PVC insulation. They are included in UT195DS multimeter. HKJ (also a memeber here) tested their resistance as 14mOhm per lead with 88cm lead length (https://lygte-info.dk/review/DMMUNI-T%20UT195DS%20UK.html).

My guess is any multimeter probe that is designed for high current will have lower resistance than the normally available 10A probes.

[tooki]

Yeah I understand all that, but I asked what they expect to gain by further improving the leads, i.e. beyond the already-superb Probe Master 8100 they already have?

I don't see an 8100 model, so I wanted to be clear that the pogo pin style was what he has.  If not, there is clear improvement to be had by going pogo.

Oops, you’re right of course. It’s been a while since I ordered anything from Probe Master so I just wrote what OP wrote, but yeah, it’s either 8000-series rigid-tip or 8150-series pogo-pin.

As for further improvement, as I mentioned sometimes Kelvin sensing is impractical and the Fluke 2X4W system gives you the convenience of normal probes with much better performance, perhaps 100X better than a typical 2W setup. You can also get a probe set from Pomona the does something similar with almost any 4W-ohms meter.  I tried making my own, but was unable to source a decent tip end and the ProbeMaster SS tips don't work well enough.  If the OP has a compelling need to do low-resistance measurements with probes, than this is the way to go.

But that won’t help them, they don’t even have a 4-wire multimeter.

I am still unconvinced that trying to find “better” probes than Probe Master (regardless of whether it’s 8000 or 8150), if such a thing even exists, will make any meaningful difference in the 2-wire measurements they are doing. My whole point was that if you want to do better than this, they need to do 4-wire measurement, which is itself inherently less fussy about the test leads.

[Fungus]

Change your technique. No leads are perfect.

Resistance? Use four wires.

High current? Get a clamp.

[BILLPOD]

Silicone test leads BL21S2-T4SC Brymen

[bdunham7]

Resistance? Use four wires.

High current? Get a clamp.

So you have something with two power supplies on board, 3.3V and 1.8V.  They each have an 0805 current sense resistor, one 0R005 the other 0R010.  You need to verify that the correct one is installed in each location and that the resistors are reasonably close to nominal value, as in making sure the wrong part hasn't been installed.  And you have a large stack of them that you need to check right away to determine which, if any need rework.  Out of all the methods discussed so far, which one would you like to use?

[tooki]

Resistance? Use four wires.

High current? Get a clamp.

So you have something with two power supplies on board, 3.3V and 1.8V.  They each have an 0805 current sense resistor, one 0R005 the other 0R010.  You need to verify that the correct one is installed in each location and that the resistors are reasonably close to nominal value, as in making sure the wrong part hasn't been installed.  And you have a large stack of them that you need to check right away to determine which, if any need rework.  Out of all the methods discussed so far, which one would you like to use?

The OP hasn’t given us any indication that their application resembles this example in any way, but we know it’s not a use case for the multimeters they own, since they don’t have anywhere near that resolution.

[bdunham7]

The OP hasn’t given us any indication that their application resembles this example in any way, but we know it’s not a use case for the multimeters they own, since they don’t have anywhere near that resolution.

I don't know the OP's precise use case and he asked for "any suggestions".  His Fluke 289 has a 50.000R LO-Ohms (also known as SLO-Ohms) that has the exact same 1mR resolution of the 8808A I pictured earlier.  That 50R range is very slow to settle and pretty fussy, so it is hard to get the same 2-3 count stability and repeatability as with the earlier example.  Still, one might imagine that it is possible and become quite frustrated or hope that better test leads would help get that last digit to settle down.

Just to provide an idea of reasonable expectations here, the specified tolerances at 10R come out to 11 counts for the 8808A, 22 counts after using REL to compensate for offsets for the 289.  Both meters easily exceed expectations with reasonable technique.

[Randy222]

I agree with tooki.

f you want to measure low resistance, this is easy to improvise. Use a bench power supply to source a constant current, like 100 mA. Set the voltage limit low enough so it won't cause excessive dissipation in the resistor. Run this current through the resistor, and with different leads connect a DMM across the resistor and measure the voltage. Use either the power supply's built-in meter or a second DMM to measure current. Then calculate resistance using Ohm's law. This pretty close to what an ohmmeter is doing in four wire mode, except less convenient.

Just some notes:
1) The leads used for current are the "DUT" leads.
2) The test is only as good as the accuracy in amps and volts readings. 2 of 3 variables in E/IR need to have high accuracy to get high accuracy in the 3rd derived value. Kelvin types are only as good as their accuracy in measuring the amps and the volts.
3) Using the extra psu and meter(s) will likely introduce more error than just the leads themselves?
4) 2 lead or Kelvin, the measurements are only as good as the tolerance stated, which can change depending on the range setting used.

Meters that can inline a known precision resistor internally when going into "cal" mode with shorted leads, means the meter can use any leads, you just re-cal each set of leads.

I use a method for some machine work stuff. I obtain a "calibrated" and "accurate" item from which all my crap uses as a reference. Same can be done for elecrical stuff too. Obtain a precision laser trimmed "certified" resistor (usually in an IC package) and use that as the known. It could be a 1k that is certified as 1.0000213 k ohm. That's your reference item. Do the same for a cap, inductor, and some voltage reference IC. They become your references for all your measuring tools. Calibrate your stuff (if possible) to those items, or if you can't tweak the meters then at least you have a known offset you can carry along. Obviously there could be some non-linear areas of the meter, so that's why it's good for tools to have calibration maps, which I don't think any handheld has.

[shapirus]

The fluke TL175 test leads I normally use for everyday testing always seem to have 0.5 ohm resistance reading.

It's either your measurement method is incorrect, or these leads are utter garbage (or are damaged). There is no way decent leads can have such high resistance.

[BeBuLamar]

I recently got 2 set of test leads from Probe Master but they aren't for the Fluke. They are both for the Simpson meters. One is pin and the other is reverse banana. The Simpson being analog so the test lead small resistance is not noticeable.

[Fungus]

OP hasn't actually said what they're achieve yet, so... 

[tggzzz]

OP hasn't actually said what they're achieve yet, so... 

... despite being asked on at least one occasion.

[J-R]

With regard to the question about measuring the current sense resistors, I prefer to REL out the test leads/probes when they are connected to the same side of the DUT.  Then move one probe to the DUT's other terminal to make the actual measurement.  This maintains consistency with regard to how the probe is making contact with the DUT, such as the side of the probe, or the pointed tip, for example.

In addition, if this measurement is super-critical, follow the above procedure a few times in order to gather consistency info.  You may need to adjust your method.

[Randy222]

Yeah I understand all that, but I asked what they expect to gain by further improving the leads, i.e. beyond the already-superb Probe Master 8100 they already have?

I don't see an 8100 model, so I wanted to be clear that the pogo pin style was what he has.  If not, there is clear improvement to be had by going pogo.

As for further improvement, as I mentioned sometimes Kelvin sensing is impractical and the Fluke 2X4W system gives you the convenience of normal probes with much better performance, perhaps 100X better than a typical 2W setup. You can also get a probe set from Pomona the does something similar with almost any 4W-ohms meter.  I tried making my own, but was unable to source a decent tip end and the ProbeMaster SS tips don't work well enough.  If the OP has a compelling need to do low-resistance measurements with probes, than this is the way to go.

Your 2-wire 4-wire test is interesting. Are your 2-leads compensated for in any way? I ask because if they are not then we know something is perhaps off with your tests? Each test wire is expected to have more than 1.46mOhm per foot.

I did a little data searching, apply some physics. The best economical wire is likely gonna be silver plated copper wire. In kinda ideal circumstances such wire that is 12awg will give us approx 1.46mOhm per 30.48cm (1 foot). That's just for wire. Need to also account for junction points of different metals.


If your test leads are 1ft each and 12awg, we should expect to see your meter pick up a diff of ~3mOhm between 2-wire and the 4-wire test.
Your meter seems to only show a diff less than 1mOhm, displays closest 1mOhm (assumed to be from rounding), etc. Each probe wire is expected to be more than 0.5m ohm.

Another thing to note, 10.000 ohms vs 9.999 ohms can actually be way less than 1m Ohm depending of how the unit rounds off in order to paint the digital display.
Eg; if it rounds up at the 0.5 mark and down when under 0.5, a diff of just 0.0001 ohm (0.1m ohm) could mean a display diff of 10.000 vs 9.999 (1mOhm). That's a 10x differential between measured and displayed.

What if you swap out that 10Ohm DUT with the kelvin current wires to see what the wires ohm in at?

[Haenk]

Silicone test leads BL21S2-T4SC Brymen

I have the ProbeMaster (both springy and normal) and Brymen. The ProbeMasters are certainly nicer, but the Brymen are not too bad either (esp. considering the price) - so the Brymen probes stay with the Brymen meter.