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@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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