Silicone test leads

[Jeroen3]

We've just found a dozen or so broken test leads. They're all premium brand SKS Hirschmann MLN SIL, and they all suffer the same flaw.
They break just after the plug because the insulation is flexible silicone.



So, don't buy silicone test leads I guess?

edit: Obviously these have been abused by pulling on the cable. The small plug make this very likely to happen.

[Pinkus]

my guess: this should happen only if they were frequently pulled at the cable and not at the connector.

[001]

You can see destroyed WIRE, not insulation! 
So cooper sucks and silicon wins! 

[noidea]

I have found something similar with Multi Contact / Staubli silicone DMM leads as well. I am using the shrouded ones with 90° and straight connector and find they always break in about the same spot at the straight connector end. My theory is that when they are plugged into test probes and are using them normally, this is the point they flex the most as the weight of the test of the lead is pulling on it. Over time the conductors fatigue and once they start to break failure becomes inevitable.
If I can find the last one I cut apart I'll post some photos.

[targit]

Same thing has happened to 2 sets of fluke leads for me, each set lasted about 5 years in daily use. Easy enough to fix with new plugs, but a real pain when they fail while trying to track down a tricky short.

[Fungus]

So, don't buy silicone test leads I guess?

Yep. Stick to PVC, it flexes much less than Silicon.

(and you'll also save some money at purchase time).

Silicon is the test-lead equivalent of putting OLED displays in multimeters - initially attractive, reassuringly expensive, but ultimately high maintenance and very short lived compared to LCD.

[Mechatrommer]

right. plastic can protect metal from breaking because plastic is a lot harder than metal and metal is a lot harder than silicone, made a lot of sense.

[CopperCone]

Lol pvc test leads are mega fail. I would rather replace silicone. How can you stand pvc??

Mine are a few years old and still ok.

5 years of daily use is alot.. Not sure what you expect from the materials.. How old are your shirts buddy?

[BillB]

I think you guys should just stop swinging your meters around like bolas.  Your leads may last longer.

[Fungus]

Lol pvc test leads are mega fail. How can you stand pvc??

It's not about aesthetics, they last longer because they act like springs. The whole length of a PVC lead is effective one big strain reliever.

With PVC the multimeter will move across the bench before the leads are straight enough to get a solid tug on the copper inside. Not so with silicone.

[PA4TIM]

Same here. A Pomona set within a month, Agilent set (is in all those years now around 50 cm left over) and some set I do not know the brand from.  The red testlead from my Brymen 869S also within a few months. (daily use)

[CJay]

My daily drive meter has a set of test leads that are in the region of 20 years old.

Fluke Silicone.

YMMV, if you treat stuff like crap it will fail.

[targit]

I wasn't complaining about the lifespan, and as I said, simple to repair with a new connector, they always fail on the straight banana jack end for me.

[ikrase]

I wonder if this is more of a problem with strain reliefs and the exact cable layout than the actual use of silicone.

[tautech]

I wonder if this is more of a problem with strain reliefs and the exact cable layout than the actual use of silicone.

Silicone is the problem without something to extend the bending moment, it's always gunna fatigue the conductor near the end on a connector. Preformed plugs and PVC cabling can be better in this regard.
If DIY'ing it's better to add at least one layer of heatshrink on the cable at the exit point of the connector.

[Hydron]

I've had similar issues with the Pomona silicone leads (Fluke TL71 style, which are sold with various brandings). Ended up buying another set though, as the price, usability and availability were right. The old-style Fluke leads (TL75) seem more rugged and (I recall) have slightly lower resistance, but in my opinion don't feel as nice in use due to PVC insulation.

Annoyingly some of the other Pomona products are let down by similar issues - e.g. their mini (3A) probes with replaceable tips are really useful for electronics (as opposed to electrical) work, but seem to suffer badly from high contact resistance developing between the replaceable tip and it's holder. Will need to investigate other brands in the future to try and find a more reliable replacement.

[Muttley Snickers]

On a side note, just the other day I came across a recent video of a UNI-T or Unitrend multimeter where at around 1:50 it showed testing of both the strain relief and fixed leads, I was rather surprised to see Unitrend going to this extent as they do not have much of a reputation in regards to quality control.

[Electro Detective]

I think you guys should just stop swinging your meters around like bolas. 

Your leads may last longer.

 

[nanofrog]

I wonder if this is more of a problem with strain reliefs and the exact cable layout than the actual use of silicone.

Silicone is the problem without something to extend the bending moment, it's always gunna fatigue the conductor near the end on a connector. Preformed plugs and PVC cabling can be better in this regard.
If DIY'ing it's better to add at least one layer of heatshrink on the cable at the exit point of the connector.

Silicone definitely needs strain relief. 

For DIY, heat shrink does a great job of it. Personally, I find adhesive lined does even better. Particularly on larger gauge wire. 

[xani]

On a side note, just the other day I came across a recent video of a UNI-T or Unitrend multimeter where at around 1:50 it showed testing of both the strain relief and fixed leads, I was rather surprised to see Unitrend going to this extent as they do not have much of a reputation in regards to quality control.

Uni-T is weird. Some of their products look well designed and generally good bang per buck, others are utter fail. And some are just straight up funny, like multmeters without enough input protection... that have PCB layout for them, just not mounted them in. Very inconsistent.

[Electro Detective]

If you're going to play the UNI-T game, may as well hit the casino tables instead with the money

It's a better gamble, and you may even win enough the one time to buy a Fluke with reliable generic leads   

[Edison]

When I was working in operational research and development laboratories we used super flexible silicone cables.
When I finished my employment, I got a couple of them.
The yellow measuring cords are still unchanged - thirty years old, the isolation of the blacks measuring cords broke down after about twenty years. They are so flexible that you feel - only silicon without wires - unfortunately I can not get it anymore.

[SG-1]

If you store your meter with the leads wrapped around it, make sure that first wrap is loose, so it does not pull against the jacks. 

I used to unplug the leads for storage after every shift,  with my 1980s model Fluke 27, that resulted in the jacks becoming internally loose & wrecking havoc with ohm readings.  I then began to leave them plugged in & wrap them around the meter. I began to experience lead failure at the jacks. Now I make sure that first wrap is loose & does not pull against the meters jacks.  We will see how that works out in a few years...

[tautech]

If you store your meter with the leads wrapped around it, make sure that first wrap is loose, so it does not pull against the jacks. 

I used to unplug the leads for storage after every shift,  with my 1980s model Fluke 27, that resulted in the jacks becoming internally loose & wrecking havoc with ohm readings.  I then began to leave them plugged in & wrap them around the meter. I began to experience lead failure at the jacks. Now I make sure that first wrap is loose & does not pull against the meters jacks.  We will see how that works out in a few years...

Preformed 90^o banana jacks are perfectly suited to wrapping leads around DMM's.

[Electro Detective]

A loose first warp after following the 'angle' direction is the best way AFAIK to keep silly cone leads working

Have not lost any so far  (cheapskate heaven)