[Elecraft] Shack Power Wiring (was Shack equipment noise)

[Jim Brown]

On 12/12/2011 10:10 AM, Keith Heimbold wrote:
> I will confer with my electrician as I just had major electrical upgrade completed in January.  I was planning to get a dedicated 240V line installed anyway.

If you are running a 240V line to your shack, a very good option is to 
run a 20A circuit WITH a neutral. In the shack, provide two 240V outlets 
and at least six 120V outlets, all in the same electrical backbox, or in 
backboxes whose green wires are bonded together by short fat copper (#10 
or larger), or with steel conduit. All of the outlets should be 3-wire 
20A (which accept either 15A or 20A plugs). The 240V outlets get both 
phases and green.  The 120V outlets get one of the phase conductors, 
neutral, and green. Half of the outlets should get one phase, the other 
half the other phase so that you can approximately balance the loads. 
Balance is a good thing, but it is not critical.

Although #12 copper is legal for a 20A circuit, I would run #10 instead 
to minimize the IR drop under load. I would use steel backboxes and 
steel conduit (EMT) within the shack. I would also run EMT to the 
breaker panel if it was not too expensive to do so. When running 
conduit, it's important to realize that at least 90% of the cost is 
labor, and to use a size that allows for what you need. I strongly 
suggest 3/4-in -- it will hold twice as much copper as 1/2-in, and costs 
almost no more to buy and run. For long runs, it can save money or break 
even, because it's easier to pull wire in the larger conduit.  And, 
since you're running bigger conduit, you could pull in a separate 120V 
20A circuit.  BTW -- the argument for 20A circuits is the same as for 
larger conduit -- the cost is nearly all labor, so bigger wire and 20A 
outlets is a small fraction of the total cost.

This will accommodate a serious SO2R station (two 1.5kW amps, two rigs, 
computers that you plan to connect to the rig (including any attached 
printers), and other accessory gear), while minimizing power-related 
hum, buzz, and noise. This circuit should NOT be used for other gear not 
related to radio gear.

The only time you would need a second 240V circuit would be to support 
multi-op high power -- that is, two 1.5kW amps transmitting at the same 
time.

73, Jim Brown K9YC