Wire preference - stranded or solid

[WarehouseCrew]

What are the pros and cons of using stranded versus solid core wire for the electrical components? I'm not an electrical guy, but am trying to help our student's clean up the rats nest of wiring on our practice robot (may make same changes on competition robot when at the Regional).

We have been using stranded wire, but I just read that solid core wire allows you to make 90 degree bends.

Does your recommendation change based upon the wire size (eg. 12 AWG vs 14 AWG or 18 AWG)?

I'm assuming if we have a motor mounted on an arm that moves (wire needs to have some flexibility) that stranded is preferred. Is that a correct assumption?

Any issues with crimping on ends (eg. eyelet for attaching to Jaguars)?

Thanks.

[Jon236]

I would recommend that only stranded wire be used on a robot. If a solid wire breaks, you lose all continuity.

[sanddrag]

I cannot think of a single instance in an FRC robot where solid wire would be preferred, unless it was wire-wrap-wire on a hand-built prototype sensor circuit or something of the sort.

[MrForbes]

Solid wire is commonly used in houses. Houses don't usually move, so it works fine. But robots move, and the flexing and vibration could lead to the wire breaking eventually.

[Bryan Herbst]

I would highly recommend sticking with stranded.

A parent kindly donated some solid stranded wire left over from a housing project last year. It is very difficult to work with, especially if you are at the stage during which you are moving electronics around.

Our crimps (unsoldered) didn't stay on very well either.

[kstl99]

I am glad to see that all are agreeing with stranded. Solid can break with vibration, metal fatigue I believe it is called. Also, screw and crimp terminations work much better with stranded, which is why you should not tin wires before crimping or using in a screw terminal.

Lastly, 90 degree bends with wire are a bad thing. They can cause the wire to crack inside. Most wire has a minimum bend radius as part of its specs. Better to loop into a connection if possible, avoiding stress on the connection.

[nuttle]

The only thing to watch out for with standed is that is you cut short amounts from the ends, you create a bunch of short, fine individual wires that are as bad as metal shavings in terms of getting into electronics and causing shorts. Also, it is fairly easy to have individual strands break and cause the same problem. It is good practice to 'tin' the ends of stranded wire before you trim the ends and insert them into things like the power distribution board or a Wago connector. You should also twist the ends, but it is still a good idea to tin them. This should prevent these problems. We also solder crimp connectors, splices, etc. The increased reliability is worth the little bit of extra time and tiny amount of added weight.

Stranded wire comes with various stand counts, even for the same wire gauge. Finer strands are more flexible, but tend to make the above problems worse.

[DonRotolo]

But to reiterate: Solid wire has no place on an FRC robot.

[BitTwiddler]

Originally Posted by nuttle

. It is good practice to 'tin' the ends of stranded wire before you trim the ends and insert them into things like the power distribution board or a Wago connector.

Tinning of the wires to be inserted into Wago connectors is NOT recommended by Wago. The Wago's are designed to make a solid connection by actually compressing the strands in a predictable and reliable manner. Tinning the wires would prevent them from compressing properly thus reducing the contact area. There has been a discussion on this topic at
http://www.chiefdelphi.com/forums/sh...ad.php?t=69355

[Teched3]

Stranded wire comes in a variety of different # of strands (more strands = higher cost) for the same gauge wire. The greater the number of strands, the more flexible the wire. In addition, the insulation type will also affect wire flexibility. Use crimp connectors on ends that are placed on screw terminals. Aways twist the strands together, use proper wire strippers to avoid cutting any of the strands, and test your crimp connection by pulling on the wire/crimp connection to ensure a soild connection. If you can't get a small enough connector for the smaller gauges of wire, strip more insulation and double or triple back the bare wire into the connector before crimping.

Solid wire is highly prone to breaking where you strip the insulation, as it can be easily nicked, which will lead to failure if you don't use a wire stripper. Use small zip ties and Velcro wire ties to bundle your wiring paths as much as possible.

[MagiChau]

Originally Posted by Teched3

Solid wire is highly prone to breaking where you strip the insulation, as it can be easily nicked, which will lead to failure if you don't use a wire stripper. Use small zip ties and Velcro wire ties to bundle your wiring paths as much as possible.

My team placed the bundlles of wires for our claw's roller motors inside of cables resembling curly telephone cables. Worked pretty well.

[bookworm0422]

Also let us not overlook that the Game Manual does not allow us to use solid core wire any where on our robots no matter the use for it.

[Nirvash]

Originally Posted by bookworm0422

Also let us not overlook that the Game Manual does not allow us to use solid core wire any where on our robots no matter the use for it.

What rule is that?

[Teched3]

There is no rule I can find governing use of solid wire. The rules cover gauge and color coding. As the say in Missourie, "Show Me". In the end, stranded is the preferred wire of choice.

[Al Skierkiewicz]

Let's start out with the first post. Either stranded wire or solid wire can be used on the robot. Either can be bent at 90 degrees, solid will hold that bend better than stranded. The Wago terminations are better suited for stranded, untinned wire insertion of one wire only. As the wire is inserted and the terminal is allowed to compress it, more surface area is created between the wire and the terminal giving a lower contact resistance. Tinned, stranded wire often reduces contact surface area to a fraction of either wire terminations raising the contact resistance and therefore heating the contact. Although the PD can accept solid wire termination, stranded is better in my opinion. Solid wire on moving and vibrating objects is asking for wire failure due to flexing of a single conductor. Stranded wire handles vibration with far less metal fatigue.