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Fremer's Single-leg panel is absolute tweak bs

So a few months ago a video appears on Youtube with Michael Fremer and some electrical contractors installing a custom electrical service and extravagant ground rod array.

OK, but the one thing about it that’s absolute unnecessary tweaky BS is the idea of running a single leg to a sub panel, as well as only using one leg for the audio equipment in it. Who ever thought this was a good idea? It isn’t.

If you really want to get as high-end tweaky as you can this is the absolute wrong way. Run 6 gauge or larger to a sub pane.  In that sub panel you locate a 220V to 120V step down transformer and keep everything balanced all the way to the outlets. That is the best of all worlds.  High noise rejection, meets code, balanced current draw from both legs and extremely low voltage drop from the utility pole to the outlets.

Another good alternative is to run 220V to a wall outlet, and use a high quality step down transformer there. A 220V/30A circuit becomes 60A at 120V output. Running high voltage as close to the outlets as possible doubles your wire gauge effectiveness.

 

 

erik_squires
erik_squires OP
15,663 posts
 

@jea48 My mistake then, I thought there were a number ( > 2 ) of rods in the field.

tonywinga's avatar
tonywinga
820 posts
 

I have two dedicated power lines to my stereo.  One goes to the two mono amps and one goes to the front end.  I had the two circuit breakers adjacent to each other in my breaker box, which means each one was on a different leg.  I took Kingrex’s advice and moved one breaker so that both dedicated lines are on the same leg.  The stereo sounds better now.  (The white wires and ground wires from each circuit are adjacent to each other on their respective ground busses. Ie. I want the ground wires as close together as possible.)  I’m using 10AWG wire and audio grade outlets.

I wonder if the stereo sounds better now because each leg (120 VAC) is out of phase with respect to the other and so now the amps, preamp and source are all on the same phase.

erik_squires OP
15,663 posts
 

If there's a solid model or reasoning for using only 1 AC leg that is based on math I'd love to see it.

jea48
4,268 posts
 

In Fremer’s case the sub panel could have been wired for 120/240V from the start. All the audio equipment still could be fed from one Line, leg. The electrician would have increased the size of the feeders knowing he would be feeding all the branch circuits from just one Line, leg.

If an isolation transformer was used with dual primary and dual secondary windings and the primary is wired for 240V, and the secondary is wired for 120/240V to feed a 120/240V panel unless the transformer is oversized to feed all the audio equipment branch circuits from just one Hot leg to neutral the audio equipment branch circuits would have to fed from both 120V Hot leg to neutral. Therein the loads some what balanced across both 120V legs.

An example, a 7.5KVA transformer is selected for use. The transformer has dual windings. Each winding is good for half of the 7.5KVA rating. 7500VA / 2 = 3,750VA at 120V each. 3,750VA / 120V = 31.25A.

So if the secondary is wired for 120/240V, (two windings are wired in series), and only one 120V hot leg to neutral was used, (Only one 120V, 3,750VA winding), it’s only rated for 31.25A max... If both legs were used to feed the audio equipment the full 7500KVA rating of the transformer would be available. 31.25A on one leg and 31.25A on the other. But the audio equipment would be fed from both legs. Not good for audio equipment that is connected together by wire interconnects... (One Hot 120V leg to the other Hot 120V leg measures 240V.)

If the two secondary windings are wired in parallel the full 7500VA is available.

31.25A + 31.25A = 62.5A Max available.

So in this case the electrical panel would be wired for 120V only.

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