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I have to choose a cable that will be bent and may be "stretch" a bit by our users. Which gauge would you advice between 24AWG and 26AWG to resist better ? I guess it is better also to have more conductors to get a more flexible wire

For the "plastic" around the conductor which type is better (silicon/non silicon)

Thanks

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  • \$\begingroup\$ A cable that resists better (as you put it) would be less flexible, so, what are your requirements and application? Contradictions make answering hard. \$\endgroup\$ – Andy aka Jan 14 '17 at 11:24
  • \$\begingroup\$ The overall AWG won't affect flex reliability, the number of strands will. So don't use single strand cable... \$\endgroup\$ – Brian Drummond Jan 14 '17 at 11:41
  • \$\begingroup\$ It's for a radio control model hobbyists. A device for will be plugged to a radio receiver using this kind of connector and cable :g01.a.alicdn.com/kf/HTB1w1thJFXXXXb3XFXXq6xXFXXXt/…. I need to choose the wire that will be use and want it to be reliable. Current is very low so no problem regarding electric resistance. I am more concern regarding the mecanic reliability That I would like to be the best of course for a reasonable price \$\endgroup\$ – Franck Jan 14 '17 at 12:19
  • \$\begingroup\$ Having tested flexible wire for disk drive voice coil motors oscillating for 10 million seeks, I have discovered failures in how vibrating wire gets fatigue and breaks. Ensure the curved wire travels along axis in a curve rather than radially. Moving Bend radius > 10x diameter. 24/11 is better than 24/7 more strands is better. If vibration causes radial movement, re-consider. Endpoint strain-relief is critical with graduated stiffness increase to (est.) 5x stiffer over a length of 20dia. This is a common failure mode in mice, iPad chargers etc. ...few layers of thick heatshrink or silicone \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jan 14 '17 at 14:44
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Both those sizes are rather small (and probably have to be) so it would be better if you can support them in some way or use a multicore cable. For example, we avoid individual conductors smaller than AWG20 in aircraft. See, for example, FAA publication AC 43.13-1B

a. Mechanical Strength of Wires. If it is desirable to use wire sizes smaller than #20, particular attention should be given to the mechanical strength and installation handling of these wires, e.g., vibration, flexing, and termination. Wire containing less than 19 strands must not be used. Consideration should be given to the use of high-strength alloy conductors in small gauge wires to increase mechanical strength. As a general practice, wires smaller than size #20 should be provided with additional clamps and be grouped with at least three other wires. They should also have additional support at terminations, such as connector grommets, strain relief clamps, shrinkable sleeving, or telescoping bushings. They should not be used in applications where they will be subjected to excessive vibration, repeated bending, or frequent disconnection from screw termination.

Chances are for a hobbyist who will only use it for short run times, you would be fine with ordinary stranded 105°C PVC insulation AWG24 wire. If the wires get flexed continuously during operation you may wish to go for a higher number of strands, thicker insulation. We use a very expensive PTFE/Polyimide insulation system, but I don't think you need that unless you're building military drones.

The terminations may be of more consequence than the wire itself- failures tend to happen near the terminations if the wire can bend sharply and repeatedly near (say) a crimped or soldered connection then it will tend to fail there. Always try to keep the wire strain relieved and constrained so it can't flop around or bend back and forth unnecessarily and does not have to bend sharply unnecessarily.

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AWG should be selected by current rating, inductance and resistance (if it's a long wire) and compatibility with your connectors. With given AWG you will be able to get any mechanical properties (or almost any). Usually for high numbers of bending or torsion cycles you will look for robotic cables (hundreds of thousands of cycles, or even millions). Isolation- take teflon, if it's not too expensive.

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