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The 210V is derived from a three phase Wye Network. If you measure from Hot to Neutral it should be 210/SQRT3 = 121V. While you are there with the meter, what's the voltage between the audio and office circuit on the Neutrals and then the same for the earths. If you have anything other than zero, let's talk.
@1.5 - of note is that I discovered that 29 is the Office and 27 is Audio. If it is 3 phase, does this mean A, B, C, per each row?If so, it means that Audio is on A, while Dishwasher is on B, and Office on C...(I had mistakenly identified another "study" breaker as the Office circuit when it was just "study lighting".) Maybe the wiring is okay to the Audio room but the leg is bonded somewhere at the panel?Would it be worthwhile to just swap Audio / Office at the breakers?
The voltages for the Earth on circuit A, B or C should be 0.00V. The same with the Neutral, the differences in voltages must also be zero, because the neutral and earth are bonded at one point only, although looking at this install, it seems not.Having a voltage difference could be due to your meter adding harmonics from loads which can exaggerate the reading, but lets say the effect of harmonics is out of the question for now. Take the same measurement again, this time unplugging everything.If you have two outlets and measure the difference in neutrals, then whatever you plug in that bonds the two circuits, will yield a better connection to the neutral than the house wiring.If say your tuner is connected to receptacle on A phase, and the amp on B phase, the neutrals not being zero volts between each other, they will find a way back to the neutral at the panel by the best path. It is then very likely that your interconnect will provide the better path, and you will hear this.A more insidious way for the neutral to return is that there is a difference in neutral voltage on receptacles on the same line. Once again you might plug in the audio components on two receptacles, and one has a better connection to the neutral, and this will also create hum since the better neutral current will flow through your interconnect.Here's where to go forward:Get the super to thoroughly go through each receptacle one by one, and clean up the connections, and at the panel. Bond the earth and neutral at the transformer, not the panel.Obtain a double wound isolation transformer 120V/120V which will lift the neutral off the electrical system, and run your audio components from that. I would really recommend a Torus/Equitech/BPT symetrical voltage design transformer after the isolation transformer to get rid of further crud. Speedskater poo poohs these devices and will present all sorts of evidence why they are not as effective as something else, however the audible distortion when my mac mini was running from the normal supply was very noticeable when I was too lazy to change the AC supply to the Equitech the other day. A big change. Don't care, I'm sticking to what I hear.
The problem will be finding someone competent at "housing" to do the work. If I can make a clear case to a supervisor of a danger of fire or damage to the house, they will come in a second and wire it properly. I will do some research on how to achieve this; remember, it is my employer who provides housing and it can tough to get things looked at this closely, I'm sad to say. Can I make such a case?1. What exactly do you mean by 'clean up the connections'? New wiring? Re-terminate and bond wires together?The hum on my system is very low level, but I wonder if unbonding the ground and neutral in the house would improve upon this...Right now I have a Cullen modded AC outlet > Emotiva CMX2 > PS Audio P3 using Magic Power cords and the amp and DAC are in same PS Audio outlet. I will re-check the two circuits with everything powered down, maybe when I notice the P3 buzzing at night.Can anyone recommend an Isolation Tranformer that is small that I could try on the DAC and amps? Total they 200 watts max. I did order a Signal DU-3 but backed out due to the 80lbs weight. Maybe I could try a smaller unit after the P3...
Obtain a double wound isolation transformer 120V/120V which will lift the neutral off the electrical system,Surely you are not implying to let both output leads of the secondary winding to float above ground? If that is what you are saying it would be dangerous. By Code the separately derived AC power system must be wired as a grounded AC power system. One lead of the 120V secondary winding shall be intentionally connected to earth and become the “Grounded Conductor”, the neutral conductor. The bonding to earth shall be made at any point on the grounding electrode system of the main electrical service.
One thing at a time. The secondary circuit of the isolation transformer can be protected by GFCI/RCD, 20mA sensitivity is fine. Any shorts to a ground, or leaks will cause the RCD to trip safely. In the case of the symmetrical power, GFCI/RCD is mandatory. It's about time your NEC caught up with the rest of the planet, by installing mandatory GFCI/RCD for all domestic and lighting circuits, not just bathrooms.Anyway, NEC rules do not apply in foreign countries, it's not legislated. Here are some examples of differences between say Euro norms and NEC.Earthing - NEC practices allows an earthing cable to be attached to a metal frame to earth apparatus, even if the frame is secured with fasteners. Prohibited in EU, the earthing conductor can only do the same if the frame is a fully welded construction, or the earth is obtained on the same connection rail as the incoming earthing conductor.Flexible conduit can use the sheath as an earth conductor. Prohibited in EU, earthing conductors must be provided.This always confuses, Black Hot, White Neutral, Black is a phase colour in portable cabling only. In fixed installations, it's the neutral. White is also a phase colour.
If the secondary is floating above ground there is no reference to ground. A GFCI would be worthless.A GFCI does not require a Safety Ground (EGC) reference! The GFCI only examines the current in the Send and Return wires, if these are not equal (5ma) then the unit trips.As a matter of fact, GFCI's are often used in older homes that only have two wire circuits (no Safety Ground wire). In this case there is some fine print.
The GFCI does not need or use a external reference. It is only aware of the current in the Send and Return wires. As long as these two currents are about equal the GFCI is happy. In any case, current is not interested in going to the ground or into the dirt, it is only interested in getting back ti it's source which is that big power company transformer outside.Note the scope of Article 517:517.1 Scope. The provisions of this article shall apply toelectrical construction and installation criteria in health carefacilities that provide services to human beings.Article 517 building follow a very different set of rules and wiring practices than do residential building.
Look at it this way, a typical home has a single phase 240V (120/120) service. If the GFCI circuit is connected to the 'A' leg/pole (aka phase) and it's Hot 120V wire leaks to the 'B' leg's Hot 120V. There will be leakage current (after all these two Hots are 240 Volts apart) so the GFCI will trip.
My original statement was:A GFCI does not require a Safety Ground (EGC) reference! The GFCI only examines the current in the Send and Return wires, if these are not equal (5ma) then the unit trips.Just how is that statement incorrect?***************************************************from your first link: Don't let the name confuse you — these devices will operate on a circuit that does not have an equipment-grounding conductor.
"This leads to all sorts of questions. The straight bare copper wires that run horizontally parallel quite neatly are earth wires, one of them bottom RH corner is a green, assume the rest are earth wires. They terminate on corroded screw terminals directly on the chassis. The brown wires are they bare cables then, yes, earth wires. Whether they bond pipes or are in themselves earthing conductors, should nowhere be connected to the neutral"
