[sdiy] Studio Electrical Wiring Questions

[harry]

Hello Shining One...
<snippd>

BrightBoy wrote:

> A friend of mine recommended that I have a second 100Amp service brought
> to the house which would strictly power the studio with it's own
> seperate
> isolated ground (attached to a seperate grounding rod).  This would
> involve
> adding a 2nd power meter, breaker panel, etc.
>
> Is this really worthwhile or not????

Do you need that much power ???

> If so, does it even meet the NEC????
>
> After reading over Article 230 (230-2) it seems that it might not be
> allowed....

It should be OK.... the utility often installes multiple feeds / meters as
a rule for HVAC etc... The separate grounds are not really an issue... they
will be ONE ground... but joined at the point of your preferrence (the entry

to the building).

> Or would I be better off just wiring the studio to the existing breaker
> panel and getting an Equi=Tech balanced power unit????

I'm doing something very similar... I had a transformer custom made for
myself.
Its a 1300VA Toroidal Transformer, with a 120VCT winding. I have a separate
ground rod on the secondary... so its really +/-60VAC.  Then this is in a
separate
metal box... and all studio wiring is done with PORTABLE CABLES (extension
cords) to that single box. So there are no ground voltage differences... it
a
pure star ground.  I also use Faraday Shield in the Transformer, to
eliminate
capacitive coupling.

I turn it on and off with a 30A DPST switch, with massive MOVs to take any
kickback.  NOTE that a 1300VA transformer is about the absolute max you
could
put on a 15A circuit... at this the inrush current is GOD awful. You need
that 30A
switch and more....

If you had 230V I'd consider having the transformer dual wound so you could
run
the primaries in series at 230V.... less R drop in the feed wiring.

>
>
> Will the Equi=Tech system prevent other loads in the house
> (refrigerator, furnice, dehumidifier, etc) from dirtying up the power
> to the studio????

Yes it works quite well... BUT if you have guitars there is another issue.
Radiated magnetic fields.  I would route ALL house wiring away fro the
studio...
do not allow wires to run overhead.  If you absolutly MUST... then run them
in steel conduit where they cross the studio.  And keep the fridge, TV
etc away from points right above the studio.

I run all power cables on the floor... and all audio wiring from hooks
overhead
in the ceiling. This way they are seperate...

Is it worth it ??? My studio is very quiet... I've eliminated bad wiring
practices
so that I didn't get much help from the balanced power anyway.  It does give

isolation and a "one switch" turn off the whole shebang feature.

BUT FOR GODS SAKE (lot of deity this post...) do NOT plug ANY studio gear
in from ouside this system of you run a real hazard. A badly grounded
chassis
(Tube Guitar Amp perhaps ?) might tie the  earth ground to neutral... which
you
then tie to another neutral that is really 60VAC... and to earth ground
again... OOPS
thats a really BAD BAD ground loop... one that could do some SMOKIN!

>
>
> I've also been told by another electrician (Larry Hendry) that if I run
> a 2-pole 220VAC circuit to the studio (from my existing breaker panel)
> and then split it into two 110VAC outlets I should be able to acheive
> lower noise figures than running two seperate 110VAC circuits
> (especially
> if I load balance between the two outlets derived from the 220VAC)

Larry is essentially correct. The idea would be for you first of all, to
have a dedicated
line to the studio... and if the lines are balanced the drop in the neutral
conductors
'should' cancel out. If those were lamps or some other well defined, static
(unchanging) load it would work.  In yyour case the benefit would be that
there would be on extra R (resistance) voltage drops caused by current
flowing in loads
that were NOT studio related (the fridge, fer instance...).

Keep things far away from the studio and you will have a more quiet life.
And pay
lots of attention to your audio gear in the racks... its usually an order of
magnitude
BIGGER problem than your electric feeds....

Its not really confusing... just frustrating. Most electricians do not
comprehend
the need for reducing magnetic fields so they don't do it. Its really hard
to
retrofit....

H^) harry

>
>
> Sorry for all the questions, but this is fairly confusing even for an
> electrical engineer....
>
> Cheers,
>
> Jeff R. Dec