Low Voltage Wiring

Multi strand works well with crimp connectors, as it conforms to the crimp. Solid won't deform with standard crimping tools, and the connection can easily come loose.

Soldering is fine to connect them, shrink tube is great stuff. Clean off the flux, I use alcohol and a toothbrush.

Thank you Mike

In RF reduces the skin effect resistance (litz wire).

From some experiences I have had with electrical and pulse power systems, I have learned the current travels mainly on the surface, so multi-strand wire has much more surface area to conduct the current.

Thank you to all for the responses. In regard to this answer why do we use solid wire as opposed to multi strand in residental wiring?

Cheaper, terminates well with devices used (no lugs required) and it works ok$$$$$

1. Flexible
2. Parallel paths , so redundancy.
3. Reduced skin effect,
4. as said easy crimping.
5. Easy bunching using cable tie.
6. Cascade routing.
7. ..
8. .

Impedance builds fast in solid

The two options will achieve the same purpose but they have different acceptability functions base on their advantages for particular use.

Stranded cables are preferred for circuit runs with rigorous contours and sharp bends. For cables used on control devices and control panels, flex cables(stranded cables) are recommended since there are too many bends and terminating is more secured on components than solid wires.

More so solid wires can easily pull out of the terminal or break inside the insulation without one knowing, crimping on solid wires is unusual and not guarantied.

Dickson

In many wire applications the wire is flexed through an arc. The flexing creates mechanical stress in the wire and results in fatigue failure. More strands of smaller diameter wire reduces the flexing stress and extends the fatigue life of the wire.

10 feet of stranded wire of a certain weight can carry more amperage than a solid wire of the same length and weight. with less resistance. electricity flows on the outside of wires, so stranded gets you more outside surface area. If you run solid wire to your cars battery, alternator and starter, you will soon have problems. If i am wrong, by all means, speak up. charles

You are not wrong, but I think you overlook an important point. Your car's electric system is DC so there is no skin effect. Therefore, it's only the cross sectional area of the wire that determines its electrical resistance. Solid copper wire is stiff, difficult to bend and has limited fatigue resistance. I think you will find that the most important reason for using stranded wire is for increased flexibility and fatigue resistance.

The best reason to use stranded wire is that it conducts electricity better. take for instance #12 AWG wire if it is solid then you only have 1 conductor; if it is stranded then you have 19 seperate conductors sharing the load.

The reason for this is called the "skin effect." The current actually flows along the surface of the conductor so:

1. If you use a solid conductor then there is only 1 surface .
2. If you use stranded conductors the there are multiple surface areas for current flow.

I don't like to be a party pooper, but if you think wire is stranded for better conductivity, please take the time to read http://en.wikipedia.org/wiki/Wire#Solid_versus_stranded

Wire is stranded primarily for increased flexibility and fatigue resistance.

I don't trust wikipedia. I do however trust the NEC as a licensed Journeyman Electrician with over 20 years Exp.

wiki is a good general information source but a better source for references.

the NEC though extensively detailed is in need of several updates too.

So, you don't trust Wiki and you think that makes you right? How about Standard Handbook For Electrical Engineers (Tenth Edition) which says in part " Stranded conductors are used generally because of their increased flexibility and consequent ease of handling." The handbook then goes into a lot of detail which you wouldn't be interested in because you haven't accepted the fundamental premise. I recommend that you and your journeyman electrician listen to the opinions of engineering experts before spreading bad information.

NEC section 310 ampacities for conductors.

NEC (2008) section 310 has nothing to say about "skin effect". Skin effect has nothing to do with the answer to OP's question and does not affect the ampacity of stranded or solid conductors at either DC or low frequency. The only relevance of NEC 310 is that it says you should not be calculating ampacity without engineering supervision.

310.3 "Stranded conductors Where installed in raceways conductors of size 8AWG and larger shall be stranded." This specifically relates to the hysterises due to only one surface area on a solid conductor.

310.10 FPN(2)

NEC 310 doesn't say anything about skin effect or about hysteresis. You shouldn't claim to have a good vocabulary unless you understand the meaning of the words and can spell them correctly. The reason for calling for stranded wire in NEC relates to flexibility, not skin effect or hysteresis. The point about corrosion is well taken. It is one of the weaknesses of stranded wire. More surface area = greater reaction with the environment.

In order to obtain a Journeyman Electrical license we are required to calculate ampacities because even engineers make mistakes sometimes. A full 1/3 of the 8 hour test is calculations.

Then you should have paid more attention in your technical classes. skin effect has negligible effect at low frequency and the extra cost of stranding would be better used for the tiny amount of copper needed to make up the difference in Ω/m.

One issue hat no one has mentioned is corrosion. Thicker stranded wires or solid wire is much less prone to corrosion than multi-strand. A tiny amount of sea water will ruin a heavy 50mm (1# AWG) welder cable in no time while a single strand 2.5mm approx 14AWG) will still continue to work even when visibly wet. Of course it is good practice to keep water and electrics apart but..........

Chas