[Elecraft] Elecraft Digest, Vol 114, Issue 11

[Joe Subich, W4TV]

On 10/7/2013 5:31 PM, Don Wilhelm wrote:
 > Geesh, how is that possible - twice the current equals twice as much
 > heat and will exceed the capacity of the wire.

Sorry, Don ... twice the current => *four times* the heat.  Heat
(energy in Joules) = Watts * seconds.  One Joule (one Watt-second)
is 2.78e-7 kW*h

73,

    ... Joe, W4TV


On 10/7/2013 5:31 PM, Don Wilhelm wrote:
> Geesh, how is that possible - twice the current equals twice as much
> heat and will exceed the capacity of the wire.  The current rating for a
> wire is the *same* no matter what the voltage.
> Also note that the safe rated current is different for wires in a bundle
> and for a single wire - the heat is not dissipated as easily in a bundle.
>
> Now if we are talking about Power delivered to the load, that is an
> 'horse of a different color'
> twice the power can be delivered over a wire (of any gauge) at 240 volts
> as opposed to 120 volts.
>
> A bit of study on basic Ohm's Law (both for EI&R and for EI&P should
> make all that clear.
>
> 73,
> Don W3FPR
>
> On 10/7/2013 2:51 PM, Richard Fjeld wrote:
>> I better say 'twice the current carrying capacity'.
>>
>>
>> -----Original Message----- From: Richard Fjeld
>> Sent: Monday, October 07, 2013 1:44 PM
>> To: Brad Blasing ; elecraft at mailman.qth.net
>> Subject: Re: [Elecraft] Elecraft Digest, Vol 114, Issue 11
>>
>> I didn't check your figures, but I agree with your understanding
>> except at
>> 240 volts, that same wire gauge would have twice the capacity.
>
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