400 watts @110volts = ? amps @240 Volts.

Discussion in 'Motorhome Chat' started by zaskar, Dec 10, 2008.

  1. zaskar

    zaskar Funster

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    Title says it all (hopefully!:Laughing:)

    Basically, there is a HOTROD available for the Atwood/Suburban water heaters which uses 400 watts at 110Volts.
    What I'd like to know is, when I'm on a 240Volt hook up, how many of my precious 10amps is that gonna use?:Eeek:

    p.s Being sad (and bored at work!) I'd appreciate seeing the relevant formulae.
    I tried Google and confused the hell out of myself!:Rofl1:

    Ta:thumb:
     
  2. scotjimland

    scotjimland Funster Life Member

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    Hi

    400 watt is the power, dived by the voltage for the amps..

    ie watts = Volts x Amps

    your answer is, less than 2 A on 230v
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  3. zaskar

    zaskar Funster

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    Ah!:BigGrin: Thanks Jim. I thought it would be more complicated than that.:Doh:
     
  4. scotjimland

    scotjimland Funster Life Member

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    Hi
    Don't worry, someone will be along soon to complicate it :)

    how many motorhomers to change a light bulb ?
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  5. American Dream

    American Dream Read Only Funster

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    Last edited: Dec 10, 2008
  6. zaskar

    zaskar Funster

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  7. American Dream

    American Dream Read Only Funster

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  8. stagman

    stagman Deleted User

    You probabally will need a 240v to 110v transformer that can handle at least 6amp on the secondary side i.e the 110v side :thumb:
     
  9. PeteH

    PeteH Funster

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    Pedantry

    Hi

    400w @ 110v = 3.6?????? amps 400w @ 220V = 1.81???amps

    400w @ 240V = 1.66??amps

    A 2:1 step transformer with primary pd 240vAC will produce 120vAC (ignoring losses) Good quality transformers will have several "tappings" allowing selection of an output voltage nearest to your requirement.

    The "hot-rod" will cope with just about anything from 100 to 130v.

    Don`t forget to specify the Frequency rating, its not particularly critical BUT a transformer is designed for use on a certain frequency and "Off Frequency" can sometimes produce an anoying "humm" or "buzz". "overspec" can be expensive and a 5 to 6 amp rating on the secondary side, as suggested, will be more than adequate, you MAY even have one on board IF you are still using the American spec; Microwave etc? If so check its rating as it may be capable of taking the hot-rod as well?

    Pete
     
    Last edited: Dec 10, 2008
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