"Ideal" power line from Service Panel

[Pano]

Hi Joesph - and welcome aboard.

I"m not quite sure I understood your description above, so more info would be great.
Do you have a link to the Trainor PowerPoint? Would love to see that/

[Printer2]

Originally Posted by panomaniac

Hi Joesph - and welcome aboard.

I"m not quite sure I understood your description above, so more info would be great.
Do you have a link to the Trainor PowerPoint? Would love to see that/

Possibly this one?

http://www.wrapair.org/forums/amc/me...ew11_11_09.ppt

[prairiemystic]

Originally Posted by Printer2

Possibly this one?

http://www.wrapair.org/forums/amc/me...ew11_11_09.ppt

That URL is for a PPT prez on air quality and climate change...

[Printer2]

Originally Posted by prairiemystic

That URL is for a PPT prez on air quality and climate change...

New computer and I have not installed Powerpoint viewer yet, sorry about that.

[Pano]

Joeyou3 sent me the PPT in question (also as PDF). Thanks! A good read. Nothing there about audio or noise on the lines, but lots about safety and proper grounding/bounding. The safety of return paths.

I'm not sure if I can post it here for copyright reasons. I will check.

If you care to research, much of it deals with the great improvements in the NEC of 1999. Article 250 of the NEC is where you want to read. The 2008 edition of the code should contain the good grounding practices.

[joeyou3]

There is no copyright protection on this presentation, and both Tom and Myself are approved to post comments on the NEC per The National Fire Protection Association. I am a member in good standing with this organization.

[Pano]

OK, cool! I'll try to figure out how to get the file size down small enough to post here.
Thanks.

[smokinghot]

Originally Posted by Jim Leach

It looks like (from the last post) that I need a heavier wire still to make the ~50' run across the house. Perhaps 8 ga to keep the drop less that 1%.

So by chance have you tested to see what voltage your utility is providing you? Are you going to design around peak usage of your neighbours or minimum...? My point is, for all you know the 1% voltage drop could be giving you 120v exactly at the equipment connection point. Or, you maybe even getting more than 120v.

Bashing your head against a wall over a 1% drop is a waste of time. You'll get greater variations during the day from the utility.

[prairiemystic]

Originally Posted by smokinghot

Bashing your head against a wall over a 1% drop is a waste of time. You'll get greater variations during the day from the utility.

It's not about what the line voltage is steady state, but rather preventing it from being "mushy" under dynamic conditions. Example - movie with dinosaur walking stomping feet, you get a power draw of 1000W then 100W then 1000W then 100W... so the line voltage will go up and down. I'd have a lot of plaster on the floor... and the neighbors calling the cops if my system was cranked like that.

[anatech]

Hi Printer2,
Sorry, I should have commented sooner.

... mainly my way of directing thought towards this issue not trying to say others did not feel it also important.

That's fair enough.

I am new here and wanted to keep my posts simple so all could understand.

Well then, welcome to diyaudio. I hope you find enough to keep you interested. You will find members who have levels of understanding from less than what's normal to very advanced. I understand where you are coming from.

But the question is how likely in the OP's current situation will he need twisted power lines in metal conduit?

For what it's worth, I think twisted pairs in metal conduit is completely unnecessary. Having said that, most Romex is twisted once you get beyond one pair and a ground. Anything I've ever worked with anyway. So those people who feel this is a critical thing, just buy four conductor Romex and you're set.

Sometimes internal filtering is used to prevent that noise from getting out?

Yes. Most computing equipment use these filters to prevent the electrical noise they generate from getting out into the wild. In commercial phone systems, they often also employ common mode chokes to keep each flavor of noise on it's own side of the fence.

I would think that is pretty much the function of a power supply other than to store energy.

If the designer has done their job properly, yes. However, since these filters are in fact used to pass EMC radiation standards, you can guess how well noise is normally controlled in equipment. That's actually a little unfair to designers. Noise can be generated by switching power supply operation - some operate in the MHz regions these days. Other things like impact printer heads and similar things may generate a fair amount of noise. Just imagine how much electrical noise was generated by old power drills, vacuum cleaners and mixers! The list goes on and on. I can say that from personal experience, most consumer devices have really poor power supply designs. Audio sound equipment tends to be really bad. The push for higher and higher supply capacitance ignores the fact that internal inductance is higher with increasing capacitor values. Same effect as the capacitors are miniaturized. Very little though seems to be directed towards actually delivering clean, low noise power to the circuitry. Some do, most do not.

Those filter capacitors are there to deal with it.

The filter caps can't deal with these higher frequencies very effectively. There is often series inductance to deal with, and the caps are not sized appropriately to deal with those higher frequencies. The best way to deal with rectifier noise would be to extend the charging time per cycle (= smaller capacitors), or use another method that draws energy through more of the AC cycle. You want to reduce the generated noise and fast rectifiers coupled with larger filter capacitors only generate more noise. This noise also couples back through the transformer secondary windings to bath other circuits in the electronic sludge. Nice eh?

I meant big capacitors relative to the rest of the piece of electronic equipment we are talking about. Generally they are the largest capacitors hanging about.

I'm sorry, you lost me there. My point is the basement "modder" that uses large filter capacitance as one of their money generating procedures. I feel actual service centers that do this should be judged more severely, since they are supposedly properly trained in electronics. Customers look to these people as experts in the field, and some work I have recently seen points to the work of morons.

You only have one phase coming in your home.

They may send one phase to the local transformer, but we normally have two phases. There is 208 VAC (nominal) between them. That has sure to have been increased as the 117 VAC (nominal) now measures 125 VAC in many places. My house is one example of this. At least the noise on the line isn't bad.

We are talking about house wiring here were we not?

Yes. I mentioned an example of twisted Romex earlier on. Most AC wiring is not twisted. I have seen twisted feeders entering the house from the pole. No idea in the below ground delivery.

The ground is precisely where you want the noise to go. Where would you put it?

Well, to the ground. However, the question is "when is a ground, not a ground"? One of my favorite questions to ask technicians. The answer? Depends on the system reference. If you look a the point of ground in a piece of equipment, you could look at the ground terminal as ... ground. But, if you consider the entire group of components that make up an audio system (for example), each ground wire is most definitely not a "ground". In truth, you do not want to run any current of any kind in the ground wire. It's there as a reference. RF current from radios will merrily travel down this connection, as well as the neutral connection. They are one and the same at the box grounding point. If current does travel down the "ground" lead, it encounters both resistance and inductance. This will create differentials across various "ground" connections depending on how much current flows down each, and what the impedances are in each leg. Notice the nasty word "impedance". AC noise filters that dump HF noise currents down the "ground" terminal will make this worse. Really, it should simply be made 100% common mode, radio RF should travel back along the neutral. Of course, it will appear everywhere due to capacitive coupling.

I do not think it crusading, my saying that the new plan of attack by the OP is a waste of time.

Okay, that certainly makes sense, and I agree.

While I am no expert on all things audio or power related I have seen a few things. Just thought I would give my opinion.

Well then, your experience does entitle you to an opinion based on your experience. Not many people actually have first hand experience with this. The only thing to remember is that medical and military gear has far better power supply design than consumer stuff. So some of your assumptions in that direction should be flushed when considering the average bit of audio gear.

-Chris