Larry the Cable Guys

@kijanki,

Great post as usual.

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kijanki Said:

Just one observation. Thicker wire has lower inductance.

@kijanki

Da,... right you are. I don’t know what I was thinking. I guess my brain turned off when Michael from Essential Sound Products spoke about smaller gauge wire paralleled to equal a larger wire had a lower inductance than one single solid conductor having the same ampere rating. ( If you go to time marker 5:25 on the video you will see Michael talking about wire gauge and inductance. He does talk about higher frequencies but I doubt frequencies in the 20K range would be present in a 60Hz mains power system.

Jea48 said:

How you get there without changing the phase relationship between the voltage and the current. Increase the wire gauge be it solid or stranded increases the inductance in the circuit. That will cause a phase shift between the voltage and the current. Ideally you want the two in phase.

Obviously the above is poorly worded, and false. I Knew better. My bad...

So when you parallel four 20 gauge individually insulated wires, that gives an equivalent wire gauge of 14awg wire, (15 amps), is the net inductance the same for both conductors?

If you get a chance would you watch the video time marker 5:25. Did I misunderstand what the guy said about the inductance?

Also if the inductance is the same for four paralleled 20 gauge individually insulated wires as a single 14 gauge conductor how about the capacitance of the cable? Will it be higher than using a single 14awg conductor?

Thanks,

Jim

@jea48   I believe that he is simply wrong.  Thicker wire has lower inductance.

Example:  2mm dia wire (gauge 12) has inductance of 345nH/ft, while 1mm dia wire (gauge18) has inductance of 388nH/ft  (not much of a difference)

As for capacitance - single wire or single pair of wires will have less capacitance than multiple wires or pairs - both overall capacitance between wires and capacitance to shield (if any).  

Inductance of the pair (cable) will be higher when wires are apart (proportional to area between them) so getting them close is important, better yet twisting them.
Twisting reduces inductance of the pair but increases capacitance.  Inductance is important in speaker wires more than capacitance so twisting is beneficial.  In addition twisting exposes wires evenly to external electric or magnetic fields reducing pickup (by cancelation).  It works fine for offending signals with wavelength much longer than the pitch of twist.  For low frequency electromagnetic interference speaker cable is too short to become effective antenna (1/10 wavelength antenna at 1MHz is 30m).

So when you parallel four 20 gauge individually insulated wires, that gives an equivalent wire gauge of 14awg wire, (15 amps), is the net inductance the same for both conductors?

Each of four individual wires will have higher inductance but connected in parallel most likely won't result in 1/4 of individual wire inductance (lower than inductance of solid 14 gauge wire) because they are in magnetic field of each other.  I suspect overall net inductance will end up the same as inductance of individual solid gauge 14 wire.  

Curiously, the Neardost Odin Gold cables have the same architecture. I shortened one recently to make it fit and was amazed at the complexity. Great post by the way. Thanks. 

@jea48   What I said before about 4 wires having the same inductance as equivalent 1 wire would be true if 4 wires fit in the diameter of solid 1 wire - not possible because od added insulation.  With larger overall diameter of multiple insulated strands wire inductance should be lower IMO.