Not looking for cable brands or model recommendations here.
What I'd like to learn is links or good reading material on what is important in a quality power cable design.
Nothing exotic, just solid engineering principals.
Example:
When is shielding (and no shielding) a good idea?
Is power amp cable different to source equipment power cable?
Is larger gauge conductors always better?
What's important low capacitance or inductance?
Solid conductor VS stranded conductor.
Finally, why is a separate ground conductor needed if the shield can be used as the ground conductor?
you know, reasonable questions.....
What I'd like to learn is links or good reading material on what is important in a quality power cable design.
Nothing exotic, just solid engineering principals.
Example:
When is shielding (and no shielding) a good idea?
Is power amp cable different to source equipment power cable?
Is larger gauge conductors always better?
What's important low capacitance or inductance?
Solid conductor VS stranded conductor.
Finally, why is a separate ground conductor needed if the shield can be used as the ground conductor?
you know, reasonable questions.....
Oh goody, a cable thread!
To start the ball rolling, I think I know the answer to the final question. The experts will soon tell me if I'm wrong!
The shield is not designed or intended to carry fault current. A power cable would only require the shield to be connected to ground at one end only to prevent circulating ground current or noise.
To start the ball rolling, I think I know the answer to the final question. The experts will soon tell me if I'm wrong!
The shield is not designed or intended to carry fault current. A power cable would only require the shield to be connected to ground at one end only to prevent circulating ground current or noise.
So far I’ve purchased and download it the “super cables cookbook” by Allen Wright. All that is there on power cables is that it should be a braid of three solid conductors with Quality connectors.
Could it be that is all there is to it?
No shield is recommended.
Why not?
Could it be that is all there is to it?
No shield is recommended.
Why not?
The most important consideration is that it meets safety standards.
Mains is dangerous.
Not solid conductors - it must be flexible.
Mains is dangerous.
Not solid conductors - it must be flexible.
I guess that could be said about a lot of things in life. Yet people do all the time. So far, I don’t know anyone who died from electrocution from mains power.
Wire has insulation. I plan to connect it properly. Live neutral ground, you know…
My question was about engineering principles.
Resistance, inductance, capacitance. What is the target and why….
Do you have an RF spectrum analyzer? If, so do you know how to safely measure the EMI/RFI on the AC power line? If so, measure at the plug end of your cable with it plugged into power, then measure at where your power cord goes into your amplifier. Did the cable filter out most or all of the EMI/RFI?
If you don't see much noise on the AC power line you can always find a noise source. Brush motors that draw a little arcing may serve pretty well.
If you don't see much noise on the AC power line you can always find a noise source. Brush motors that draw a little arcing may serve pretty well.
Looking for a non-existing problem. Btw there are myriads of cable threads in case that fascinates you that much.
I've see some of the spectrums. Don't know about anybody else. Common mode chokes may do more good than simple cables 🙂
In the case of a fault, the live current flowing in the earth wire is very large (so large as to blow a 13 A plug top fuse instantly).
The earth wire in the cable is necessary for safety reasons, one of which is to stop the power cable from catching fire.
On the other hand, the purpose of the shield, connected at one end only, is simply to, um, shield the conductors in the power cable from noise pickup.
That's why I said the shield is neither designed nor intended to carry a fault current.
It is arguable that to shield a power cable is necessary. I don't have shielded power cables.
I guess you are on 120 V?
Electrocution by the domestic electricity supply is not common in the UK, but we do have to take greater care.
"The domestic electricity supply in the UK is about the most lethal combination that
could have been devised. The voltage of around 240V is sufficient to cause muscle
spasm and thus a ‘hold-on’ effect, so that a live conductor may not be able to be
released. At the same time it is too low to cause a ‘throw-off’, which accounts for
many of the survivors of shocks due to high-tension conductors.
The frequency of the cycle of alternating current is in the middle of the most lethal
range for causing ventricular fibrillation." - UK NHS
Put on your fire suit, cable threads, particularly Mains cables threads become strongly opinionated very quickly.
Generally speaking, shielding is beneficial. Electrical fields are everywhere, might as well control them the way you want. Shieldeing on a mains cable helps keep the fields where you want them.
Shield must be connected to ground at both ends.
Only if you believe that three feet of mains cable can somehow have an effect on your various component's PSUs.
For mains? That seams reasonable.
Doesn't really matter... you have 15A at 120V available to drive any parasitics. I.E., the wall ain't gone to be perturbed nor effected at all by slightly higher or lower C or L.
Flexibility is paramount, as others have said. Do not use solid.
Because as @Galu already said, it's not designed to be the sole conductor of the fault current. The 3rd (green, or green/yellow) wire is, so make sure that's connected properly.
I will say, in very clear terms, make damn sure you know what you are doing when playing with mains. It can kill you, and easily. It can also burn down your house. Proper, well-made connections are a must. Do not make a power cable from materials that are not manufacturer rated for the job of domestic AC wiring.
Audiophile AC cables are, in my opinion, a way to remove money from the gullible and superstitious. I have zero qualms if you want to make some prettier cables, that's a noble pursuit. But will they make an actual difference? Only between the ears.
quick google suggests about 400 deaths per year in USA due to electrocution and about 4000 injuries serious enough to require an ER visit or entry in the accident log. What's not clear is how many of those are domestic 120V and how many are places with 3 phase or higher potentials around.
But I have at least 3 amps that don't even have a ground connection.
Air Tight tube amp
Yamaha amp
Sony amp
Rega amp
All USA, 120v versions.
How is that possible? Would not then, any ground (like the braid shield conductor) be better than no ground? And if no ground is proper in the above then how is a low gauge ground inferior to that? I'm confused... While all these cautionary words in the midst...
Air Tight tube amp
Yamaha amp
Sony amp
Rega amp
All USA, 120v versions.
How is that possible? Would not then, any ground (like the braid shield conductor) be better than no ground? And if no ground is proper in the above then how is a low gauge ground inferior to that? I'm confused... While all these cautionary words in the midst...
"How is that possible?"
Double insulation?
https://www.draelectricals.co.uk/double-insulated-electrical-appliance/
Double insulation?
https://www.draelectricals.co.uk/double-insulated-electrical-appliance/
Seek ye the answer in this old thread:
https://www.diyaudio.com/community/threads/newbie-question-screened-mains-lead.78909/
Quote: "I found a link on the TNT-Audio web site with some DIY recipies for audio mains cables, and they confirm that the shield is to be connected at the mains plug end."