Larry the Cable Guys

@jea48 

Thanks for the link.  Very simple presentation and should be read by those considering, or rejecting power cord upgrades.  I hope that @jasonbourne71 has a chance to review the information.  His resistance to mindless upgrades has always been a valuable contribution.  Not that I have always agreed with his position.

Just one observation.  Thicker wire has lower inductance.  The reason for splinting wire into separate strands is skin effect.   For copper skin depth at 20kHz is about 0.5mm *  That would suggest keeping wires thinner that gauge 18.   In plain stranded wire current would jump from strand to strand (path of lower resistance - to outside) jumping thru impurities (oxides) that are on the strand's surface.  Insulating wires eliminates that, but skin effect still exist (increasing overall impedance) since strands are still in each other's magnetic field.  That is why there are strange designs, like flat cables or wires woven in helical twist on large hollow tubes, like in my acoustic Zen Satori.  Twisting and interleaving multiple hot and returns reduces inductance,   I'm not sure if skin effect is audible since most speakers are inductive at high frequencies (higher impedance), but for some speakers like electrostats (capacitive at high frequencies) it can make audible difference.

* It means that in 2mm diameter wire (gauge 12) most of electric charge at 20kHz will not flow thru inner 1mm diameter.  Skin depth is the depth where current density drops to about 1/3.  Gauge 18 wire has 1mm diameter.

@kijanki,

Great post as usual.

.

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.