Electrical questions; wire gauges and winding sizes.

[Knuckleballerr]

Hi all, its my first post & I'm glad to be here. I can't wait to contribute to the forum where I can.

I wanted to ask first about electrical wiring, particularly stranded vs. solid core wire. What are the advantages of stranded over solid core wire other than flexibility? Do the numerous stands of wire offer some advantage?

Also, what is it about some car alternators that they can offer more amperage over units of the same size? I can understand better rectifiers and voltage regulations can be used, but is it to do with the wire gauge sizes/turns ratio in the unit?

[studiot]

Good Morning, knuckleballerr, and welcome.

 

Just a note, we have an engineering section and

a number of very good engineers as contributing members.

 

Electrical wiring?

 

Yes the decision to use stranded or solid wire is basically a mechancal one. This decision extends far beyond automotive applications and is more important than just 'advantages' of one over the other.

 

What happens if you repeatedly bend a length of solid core wire back and fore?

It breaks readily.

Stranded wire is much more resiliant to repeated flexing.

Solid core wire is cheaper.

 

So in situations where the wire is subject to vibration such as in an automobile or a washing machine you should use stranded wire.

 

In some situations such as the windings on a motor or generator the wire is supported along its whole length so vibration is not an issue.

In this case so the cheaper solid core can be used. However you have to make the winding in the first place so sufficient flexibility for this is obtained by using thinner wire. Note there are other constraints with motor windings.

 

In a building situation there is little vibration so again solid core wire takes the vote on cheapness for fixed wiring, but stranded is used for the added flexibility of connecting wire to both fixed and portable equipment.

 

It should be noted that proper connection techniques differ for solid and stranded wire, so care should be taken fitting one to a connection designed for the other.

 

Engineering is always a balance between conflicting requirements and cost is often one of these.

 

Your auto alternator is one of these. The cheaper ones have lower spec because those that are cheaper (and easier) to make have fewer poles and lighter bearings than the heavier duty ones.

Edited June 18, 2015 by studiot