[Elecraft] 120V vs 240V

Paul Christensen w9ac at arrl.net
Wed Feb 16 08:38:28 EST 2011


> This lessens the electrical loading on the 120v house circuits in the
> bedroom converted to shack.  Those circuits power the computer stuff,
> lights, antenna rotators, and some test equipment at the work bench,
> plus bench 0-30vdc power supply.

Many good suggestions here.  If for no other reason, running dedicated 
branch circuits into the shack will often eliminate light dimming.  My shack 
occupies a spare bedroom and the 120V receptacles were at the end of a 
shared branch with an adjacent room.  Keying at 100W would cause the room 
lights to noticeably dim.  Now add a 500W solid-state amp to that circuit 
and not only will the lights dim, but voltage regulation on the branch 
suffers.

This is one of those projects where it will often pay off to run multiple 
branch circuits into the shack.  If you need one, it takes little effort and 
cost to pull a couple more.  I did all my attic work in the middle of the 
hot Florida summer.  I tried to start early and finished by 11am when temps 
really start to climb.  The job was split into two days but there's now two 
separate 120V branch circuits into the shack that only power equipment.  A 
30A, 240AC 4-wire circuit was pulled ten years ago.   I now wish I had 
pulled a few more to have dedicated 240V receptacles for each amp.

It's easy to quickly run out of panel space.  I had already maxed-out a 
sub-panel and for better or worse, I used a tandem breaker for the two 20A 
shack feeds since I had a single remaining position available in the sub 
panel.

Paul, W9AC


 



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