Wire preference - stranded or solid

[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.

[Teched3]

Al,
Excellent point made on stranded wire compression at a terminal connection.

[MikeE]

There is no reason to use solid core for any of the "large wires" i.e. 22 AWG or larger, but it's fairly common to see some of the bundled data wires (RJ12 telephone cable for CAN bus or ethernet cabling) using solid core rather than stranded. I'd still prefer to use stranded for these applications but IMHO it's less critical.

[MagiChau]

If my memory serves me correctly the required power convertor for 12V to 5V solely for the bridge's power supply has solid wires for connecting it to the power supply & bridge.

[Al Skierkiewicz]

Chau,
Those are pre-tinned stranded wire. You insert one side in the connector for the PD and solder the output to the power cable for the radio. Pre-tinned seems to indicate the primary or intended customer for this regulator would solder it to a circuit board.

[wireties]

FYI - When electricity flows through a wire, it mostly flows on the surface of the wire, not through the middle. This effect is more pronounced on high frequency AC than it is on DC or low frequency AC. This means that a "wire" of a given size that made up of many smaller strands can carry more power than a solid wire - simply because the stranded wire has more surface area. Plus flexibilty is key on our robots and all the termination mechanisms we are given work best on stranded wire.

So... my professional opinion is there are no compelling reasons to use solid-core wire on a FRC robot (even if it was donated).

HTH