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Non-foo questions about mains cables

Discussion in 'audio' started by gustav_errata, Jan 13, 2021.

  1. gustav_errata

    gustav_errata pfm Member

    I'll say this up front: I am not considering buying a new mains cable for my amp to accomplish any sort of sound-quality improvement. I have read plenty of threads on that and there is no reason to rehash that argument here. My questions are basically about standard electricity concerns.

    I am only considering buying a shielded cable. The reason is that my current AV stand has a single small (<10cm diameter) hole through which all cables are routed. Presently that means my power amp's mains cable is basically sitting on the two NACA5 speaker cables where they all pass through this hole (worse, those cables need to squeeze under a shelf, which has maybe 1cm clearance from the bottom of the hole). Maybe one day I'll be able to buy a rack that allows better cable management but it's not in the cards at the moment.

    I am also only interested in buying a cable that meets all regulations, notably the CE mark but ideally also the USA UL certification. I don't want any risks. I don't want an insurance liability. To the best of my knowledge, the only shielded cable that is available that has a CE mark is the Supra LoRad series. These come in 1.5mm^2 and 2.5mm^2. I believe Naim amps, such as my own (NAP150), come with 0.75mm^2 cables.

    So, my two questions, which I'm positive are elementary, however my searches aren't coming up very successful:

    1. I know that a cable that is too small poses a risk of heating up. I vaguely understand that 1.5mm^2 should be sufficient to carry practically any current from a typical amp. Is there any risk from having a cable that is too large for the expected currents? Is there anything extra to consider in this regard with a shielded cable? Again, I want zero risk. I'm of a nervous disposition. :(

    2. I don't understand exactly what British Standard 1363 is saying about cable size. Is it that the maximum size permitted in a 13A plug is 1.5mm^2? Or is it that the maximum size that a 13A plug is required to fit by design is 1.5mm^2?
     
  2. djftw

    djftw Heterodox Member

    1. No, nothing to worry about at all. Assuming the shield is connected to earth it should actually be safer in theory, but in this application that should be of little consequence.

    2. Do you mean. "Provision shall be made for the entry and effective clamping without bending of 2-core and 3-core flexible cords for rewirable plugs as given in Table 11, Table 12, Table 13, Table 26 and Table 27 of BS 6500:2000, having nominal conductor cross-sectional areas not exceeding 1.5 mm2" Yes that is a design requirement, the plug must be designed to safely accommodate the flat and round flexible cords described in those tables up to 1.5mm2. It is not advisable to use a heavier cable with a rewirable plug unless you know the manufacturer has designed it to accommodate that, whether there is ever any point to using a larger flex is debatable, but several companies sell assembled cables using them and it isn't illegal or problematic.
     
    gustav_errata likes this.
  3. gustav_errata

    gustav_errata pfm Member

    Perfect, thanks! That is exactly what I wanted to know.
     
  4. Craig B

    Craig B Re:trophile

    Would it not be possible to use a hole saw to create a second mains cable only exit hole in the rack?
     
    booja30 and trick cyclist like this.
  5. stevec67

    stevec67 pfm Member

    As Craig says. Drill another hole, mains one side, coax or speaker cable away.
     
  6. misterdog

    misterdog Not the canine kind

    Note that such cables are far less flexible and may struggle in your limited access hole.

    Looking at that cable it has a nylon screen and a drain wire so not as 'inflexible' as ones with a braided screen.
     
    gustav_errata likes this.
  7. gustav_errata

    gustav_errata pfm Member

    Thanks, noted. Although the Supra ones do appear to be reasonably flexible. It was necessary to attain the CE mark (according to their own promo material, at least).

    I'll see what options I have for drilling a hole. Hole saw attachments don't look too expensive. Of course, once through their respective holes, the mains cable and the speaker cables will still be in relatively close proximity.
     
  8. Bairnstorm

    Bairnstorm pfm Member

    The Furutech Roxy has a slim connecting plug for the amp end and is solidly constructed. It is also shielded.

    You will see many diy'ers and constructors use their cables and connectors.

    I know you are not interested but it sounds better too.
     
  9. misterdog

    misterdog Not the canine kind

    Insulator: Audio grade polyethylene (red yellow green)
    Intervention: Cotton yarn
    Presser winding: Special paper tape

    LOL.

    Yarn - tell a long or implausible story.

    Such claims could be easily measured
     
    Craig B likes this.
  10. uncl_nigel

    uncl_nigel pfm Member

    The Supra Lorad is indeed flexible even by normal non-hi-fi standards - when not in use I coil them quite tightly with no problem.
     
    gustav_errata likes this.
  11. Craig B

    Craig B Re:trophile

    Speaking of intervention, that describes the construction of most any twisted multi-core mains flex produced since WWII, when polyethylene was first recognized as being an effective electrical/signal cable insulator (enough so, for its use as such to be kept a secret until after the war).
     
  12. gustav_errata

    gustav_errata pfm Member

    Thanks, but the Furutech cable is way out of my budget. It looks to be about the same as I spent on my (second-hand) power amp. I'm still at the stage where only unambiguous improvements due to component upgrades are under consideration. I think I'm better off not considering expensive tweaks yet.

    I also mainly wanted to avoid the usual arguments here about mains cables. We've all read them before.

    Here my main interest was in electrical safety for numpties, with a dash of noise due to poor cable-run conditions.

    If anyone is willing to go off-topic, I would be interested to hear from people who happily use non CE/UL-certified mains cables and whether or not they were emotionally scarred as a child by a seemingly endless stream of filmstrips shown at school about how their house was most definitely going to burn down from an electrical fire and how, as a 6 year old, they should have already drawn up a fire-escape plan and discussed it with their parents.
     
    steveinspain and uncl_nigel like this.
  13. Bairnstorm

    Bairnstorm pfm Member

    I' m not really sure what you want then. I have no idea if any of my power cords are CE. I have 2 Kimber, 1 Chord and the Furutech nor do I lie awake worrying about the house burning down.

    Buy the Supra if you want but if you are not interested in sound quality, what is the point? Save up for a better amp.
     
  14. Yomanze

    Yomanze pfm Member

    Very easy to work with too. :)
     
    uncl_nigel likes this.

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