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In recording studios, you will sometimes find 'technical power' which is delivered on balanced wiring from an isolation transformer. This is rarely seen outside

In recording studios, you will sometimes find 'technical power' which is delivered on balanced wiring from an isolation transformer. This is rarely seen outside of radio and television studios, though. Many performing arts spaces have a simpler version, of dedicated outlets for power amplifiers that are on an isolation transformer if anything, but usually just a separate run to the main panel - this is mostly just to avoid the ground loop problem, as you mentioned, as well as to avoid certain kinds of noise that amplifiers might pick up. I doubt that the isolation gained from having one's own pole transformer is any better than what an isolation transformer gets you. You'd still be subject to any noise or trouble in the distribution-level wiring, and at the end of the day I think most of the problematic electrical issues you could have in audio are going to originate in your own house anyway. It's probably much better bang for your buck to put your audio equipment on a nearby isolation transformer, which are not necessarily cheap but certainly don't run in the five figures (or at least not until they get very large). But with these kinds of audiophiles, bang for your buck isn't what it's about. Having known some audiophile extremists like this, at least in my limited experience, it's just a status symbol. Edit: As an anecdote about amp noise, while lighting is a pretty big issue most permanent venues have their lighting well-segregated into a central dimmer rack anyway. The most notable time I got an angry noise out of an amplifier is when I accidentally plugged a hydraulic manlift into a poorly labelled amp rack socket. When I went to ascend, the noise from the house speakers made me just about jump out of my skin, to the great amusement of my coworkers.

honkhonkpants 10y ago
Rarely seen outside of studios and hospitals. I guess people will point and laugh at this but they probably aren't laughing at FDA device safety rules. "Technical power" in your house is pretty much against all building codes. You need color-coded outlets and warning signs on all outlets and on the entry doors, in a commercial setting where the code allows such wiring. On the other hand, wiring your amps up this way has a certain economy to it; it's actually pretty cheap and effectively solves the problem for a lot less than the $10k (plus ongoing monthly costs of extra power service) cited in this article. Edit: NEC here: http://www.equitech.com/support/647.html http://www.equitech.com/support/647.html
- wlesieutre 10y ago
  Note that this is specifically for a 120V system where instead of a single hot and a neutral, you have two hot wires, each at 60V to ground and running 180 degrees out of phase. Similar to how 240V receptacles are wired in residential. For commercial buildings, the common layout to run a "computer" circuit with a dedicated ground and neutral, while sharing them between multiple other circuits for general loads. There are a lot of variations on this sort "isolated circuit" setup, and it's pretty much standard practice. I couldn't say how much most computers and other loads actually care that they share a noisy neutral, but I did have one personal experience with a building where an Xbox 360 couldn't get past a game's first loading screen because the power was so dirty. For some examples, see the options listed on page 2 and wiring diagrams on page 3 here: http://www.electri-cable.com/v/vspfiles/download/Electri-Pak/Electri-Pak_Jan%202015.pdf http://www.electri-cable.com/v/vspfiles/download/Electri-Pak...
- mindslight 10y ago
  I'd think the reason it's against the NEC is to avoid surprises during infrequent residential servicing. You could do the same thing outside of the wall though. But if you're tying the grounds together and feeding equipment that has its own transformer, I don't see much of a point. I'd also think the FDA safety rules would require it for its failure modes, not power quality. Actual patient isolation is taken care of by the devices themselves.
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honkhonkpants 10y ago

Rarely seen outside of studios and hospitals. I guess people will point and laugh at this but they probably aren't laughing at FDA device safety rules. "Technical power" in your house is pretty much against all building codes. You need color-coded outlets and warning signs on all outlets and on the entry doors, in a commercial setting where the code allows such wiring. On the other hand, wiring your amps up this way has a certain economy to it; it's actually pretty cheap and effectively solves the problem for a lot less than the $10k (plus ongoing monthly costs of extra power service) cited in this article. Edit: NEC here: http://www.equitech.com/support/647.html http://www.equitech.com/support/647.html

wlesieutre 10y ago
Note that this is specifically for a 120V system where instead of a single hot and a neutral, you have two hot wires, each at 60V to ground and running 180 degrees out of phase. Similar to how 240V receptacles are wired in residential. For commercial buildings, the common layout to run a "computer" circuit with a dedicated ground and neutral, while sharing them between multiple other circuits for general loads. There are a lot of variations on this sort "isolated circuit" setup, and it's pretty much standard practice. I couldn't say how much most computers and other loads actually care that they share a noisy neutral, but I did have one personal experience with a building where an Xbox 360 couldn't get past a game's first loading screen because the power was so dirty. For some examples, see the options listed on page 2 and wiring diagrams on page 3 here: http://www.electri-cable.com/v/vspfiles/download/Electri-Pak/Electri-Pak_Jan%202015.pdf http://www.electri-cable.com/v/vspfiles/download/Electri-Pak...
mindslight 10y ago
I'd think the reason it's against the NEC is to avoid surprises during infrequent residential servicing. You could do the same thing outside of the wall though. But if you're tying the grounds together and feeding equipment that has its own transformer, I don't see much of a point. I'd also think the FDA safety rules would require it for its failure modes, not power quality. Actual patient isolation is taken care of by the devices themselves.

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