Fremer's Single-leg panel is absolute tweak bs

@johnah5 Wrote:

I was done with Fremer when during the breaking news about MoFi he kept saying the guy who asked the question that broke the scandal wasn't a "journalist" so he dismissed it.  He has zero credibility

I agree!

Mike

For a residential dwelling unit in the US a hard wired 60/120V balanced power system is not NEC or AHJ (AHJ, in most areas in the US) code compliant. If a person can get a electrical contractor/electrician to install and wire one into the electrical system of a residential dwelling unit he will do so without pulling an electrical permit.

 

Quote:
"60/120V Symmetrical (Balanced) Power Systems Per NEC 647.1 (2008) the use of a separately derived 120 volt, single phase, 3-wire system with 60 volts between each of the two ungrounded conductors and ground is permitted for the purpose of reducing objectionable noise in sensitive equipment locations, providing the following conditions are met:

1. The system is installed only in commercial or industrial occupancies

2. The system‟s use is restricted to areas under close supervision by qualified personnel.

3. All other requirements in NEC 647.4 through 647.8 are met.

In a 60/120-volt symmetrical (balanced) power system the load current return path is not a grounded conductor, as it is for the standard 120-volt system. Neutral and safety ground are no longer tied together as in a standard electrical system."

"A major disadvantage of balanced power
systems is the requirement for ground fault
circuit interrupter receptacles (GFCI). These
receptacles can trip due to normal ground
leakage currents."

"When the GFCI receptacles are disabled or
bypassed, the system becomes an
electrocution hazard!"

"Since the noise reduction achievable with this scheme is typically only 6 to 10 dB, symmetrical (balanced) power transformers are not a cost-effective method of reducing system noise. The primary benefit (reduced common-mode noise) is due to the fact that these systems are inherently isolation transformers, whether the output is balanced or not. A standard, unbalanced shielded isolation
transformer will do nearly as well without the disadvantages of a balanced output power transformer."

Pages 26 - 27

Power Distribution and Grounding of Audio, Video and ...

/ / / / /

Quote:

"So-Called “Balanced Power”
• Properly called SYMMETRICAL power
• Has very seductive intuitive appeal
• NOT similar to balanced audio lines in any way!
• Uses transformer having 120 V center-tapped secondary
• Both line and neutral output blades are energized at 60 V
• Although advertising often implies endorsement, NEC seriously restricts
its use – because it’s potentially dangerous!
• ONLY FOR PROFESSIONAL USE
• NOT to be used with lighting equipment, especially screw-base bulbs
• MUST have GFCI at outputs
• Only technical function is to reduce leakage currents
• Leakage currents are trivial system noise sources
• Reported noise reduction generally less than 10 dB
• Any real benefit likely due to its clustered outlets."

"The theory is pretty simple: if symmetrical (equal but opposite instantaneous polarity)
AC voltages are applied to equal-valued capacitors, say C1 and C2 above, the two
current flows would also be equal but opposite and cancel each other ... no net
current into safety ground. But leakage currents flowing in safety ground
wiring are not a significant source of ground voltage differences ... as so
many apparently believe."

An Overview of Audio System Grounding & Interfacing 9/4/2012
Bill Whitlock

pages 201-202

An Overview of Audio System Grounding and Interfacing

/ / / / /

Another problem if a 60/120V balanced power system is hard wired to the electrical system of a residential dwelling unit according to NEC as well as most AHJs in the US most 120V branch circuits shall be AFCI protected. Yes an audio room that would apply... The 2 pole circuit breakers in a "wall mount" hard wired 60/120V balanced power system are not AFCI circuit breakers. I doubt they would even function if they were tried. They are not designed, manufactured, or Listed, to be connected to a 60/120V symmetrical power system.

 

.

Thanks for the clarification, @jea48

So, we can't use an in-panel balanced power/symmetrical power provider, but we CAN use a step down balanced power converter so long as it's plugged in.

Is that how you read it?

Best,

Erik

Quote:
"60/120V Symmetrical (Balanced) Power Systems Per NEC 647.1 (2008) the use of a separately derived 120 volt, single phase, 3-wire system with 60 volts between each of the two ungrounded conductors and ground is permitted for the purpose of reducing objectionable noise in sensitive equipment locations, providing the following conditions are met:

1. The system is installed only in commercial or industrial occupancies

2. The system‟s use is restricted to areas under close supervision by qualified personnel.

3. All other requirements in NEC 647.4 through 647.8 are met.

@jea48

i use an Equi=tech 10WQ Wall Panel System which does use balanced power. my electrical contractor was fine installing it since it was in a separate building, for a dedicated room "only" resembling a commercial installation. i called it my ’studio’ to my contractor.

no water in the room, or children in the room. it was a purpose built room. which met the code. only my system gets plugged into that panel.

as far as system performance, i have dirty power outlets around the room and it’s easy to compare them to my Equi=tech balanced outlets, and it’s quite a bit better sounding both for sources and amps. i’ve had a few manufacturers bring gear skeptical about my isolation transformer or balanced power. they left no longer skeptical. why my separate isolation transformer sounds better is a fair question. i have my own transformer at the street, and am in a newer development in the mountains. so you would think my regular power would be pretty good.

PS - I am pretty sure they make 2-pole CAFCI breakers these days, but if symmetrical power is not allowed at a residential wall outlet then there’s no getting around that in the NEC.