Power/current draw of AV components?

Discussion in 'Cables & Switches' started by t0by, Mar 20, 2006.

  1. t0by

    t0by
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    I am in the process of making some home brew power cables and need to choose between a cable capable of carrying 10A and a cable capable of carrying 16A. (Its the Supra Lo-Rad stuff).

    Denon advertise my AVR-2805 amp as having a power consumption of 290W. Panasonic publish the same figure for my PW7 plasma. Is it possible to calculate a corresponding ampage figure from that?

    Basically, I just need to know if 10A cable will do, or if I need the 16A stuff.

    Thanks, folks.
     
  2. Nick_UK

    Nick_UK
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    Watts = Volts x Amps

    or, to put it another way,

    Amps = Watts / Volts

    So a 290W device would take 1.2 Amps at 240V. So the 10A cable will be more than adequate.
     
  3. t0by

    t0by
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    Thanks, Nick. I did recall something along the lines of P=VI from my A level physics, but I wasn't sure if it was applicable for this sort of thing. :hiya:
     
  4. Nick_UK

    Nick_UK
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    Well, those formulas are really for DC current - many AC appliances are rated in VA, not watts. The end result for AC is actually an even lower average current, so the formula I gave would give a result which was even more generous. Most amps these days have "switched mode" power supplies, which means that the current they consume varies with the power being put out, so it's a good idea to over-rate the cable a little, so that you don't get any voltage drops during periods of high current consumption when you wind the volume up.
     
  5. eviljohn2

    eviljohn2
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    You do know that domestic sockets are usually 13A? You certainly won't find one with a higher rating. :)
     
  6. t0by

    t0by
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    Yes, I just wanted to be sure that the kit wasn't pulling, say, 11-12A and that I would need the 16A cable.

    Makes life easier all round with the 1.5 stuff as it should fit easier into the MK Duraplugs that I've bought, and the trunking inside the wall. :smashin:
     
  7. severnsource

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    I think you've got that the wrong way round. VA is used for AC devices because the current and voltage are not neccesarily in phase. If V and A are in phase the VA rating and the power comsumptiom are the same. If there is a phase difference the VA requirement will be higher than the power consumed, therefore the current drawn from the supply will be greater than that expected from the power raitng.

    In most domestic circumstances the difference is academic of course.

    Bill
     
  8. BDCSTENG GARETH

    BDCSTENG GARETH
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    I think the easy answer is:

    Use the 10A cable. I'd be suprised if you come even close to half that for most home AV units... Make sure If you use fused flugs, to make sure the fuse rating is lower than the power cable rating and you'll be absolutly fine.

    Regards,

    Gareth.
     
  9. luke.a.jones

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    Correct, The 10A will be fine.
     
  10. johnson

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    I have 15amp MK plugs and sockets on the supply to my amps.(no fuses)
    Regards
     
  11. eviljohn2

    eviljohn2
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    Without any form of protection? :eek: :mad: :thumbsdown:

    I use 15A sockets at work with lighting equipment which don't have fuses but the caveat is that they must always be used in conjunction with RCD or fuse protected supplies.
     
  12. johnson

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    No, I didn't say without any form of protection.That would be foolish.
    I'm just not doubling up on protection.
    The cable is protected and the amps have fuses on the mains iec.
     
  13. eviljohn2

    eviljohn2
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    I see, I was under the impression you were talking about the wall end of the cable rather than the device end. :)
     

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