One Thing Leads to Another!

[Tyler Howell]

As I was doing the prep for my new PM 66 I decided to bend all new pipe for the 40 Amp 240 service. I wanted to share a couple tips I've picked up over the years, and hope that Knowledge will be Power. I spied this little present from my predecessor as I was cleaning up the power distribution panel. Not surprised, the house was full of similar little gems. Hopefully I can find and fix them all.
Repairing damaged insulation in this manner is OK for preexisting wires but locally unacceptable for a new install. Clearly an installer screw up. (He bragged about this and some of his other DIY projects.)
One of the reasons I don't like Romex and the like, is it is very easy to damage the insulation. This is the 10/3 30 Amp. ckt supply for the HVAC compressor. I think this is UF-B, and It is particularly tough. Rather than cut back the insulation, I like to peal it off with knife or scissor assist. Take your time, mistakes are expensive$$. (I'm sure that’s why many cut corners because of the $$$):(

A wise old electrician that could bend perfect pipe by eye every time, taught me to scrape the paint/coating off ( poor pix) anyplace you are going to land a ground. This is my 60 amp disconnect mounted next to the saw. In the center is where the ground lug was mounted. Out of habit I checked the resistance and found an intermittent connection. I scraped her pretty good and a SS star washer gave me 0.00 ohms. resistance to ground.

[Tyler Howell]

One more area is pulling /terminating your wire. I saw 600ft. of #O AWG cable skinned to the copper by an inattentive installer.$$$$. Everything you can do to protect the integrity of the conductor and it's insulation is vital. Even a small nick in the insulation, add a little moisture some dirt and you have a hot spot. Shaving the copper, nicking it or cutting some of the strands of wire all lower the capacity of the conductor.

I go to great lengths to de burr all the EMT and green field I use.
Insulated bushings in all critical areas especially where you are pulling wire. The metal one in the middle is for added bonding, has an insulated band in the middle.
Good cutting, stripping and crimping tools. The ones on the right work but are like other multi tools. They do everything, but nothing well. NONE OF THESE TOOLS ARE OSHA APPROVED FOR WORKING HOT.
Electrocution is the #4 cause of industrial deaths. That number is higher in the home.
Good luck and play safe. More to come.

[Bruce Page]

Good info Tyler! Now finish hooking that dude up and make some dust!!

[Mark Singer]

Dust! I want to see dust!

[Steve Clardy]

Only thing I see wrong Tyler is--------:eek: the first box isn't up to par on the paint. Doesn't match the others, all nice and shiny.:D
Steve

[Ken Garlock]

Tyler, let me ask why you decided to use EMT? Was it between an adjacent sub-panel and your disconnect? Was it because you couldn't get into the wall? I am curious since the only EMT around our house and shop is the 3 inch pipe that sticks out of the ground and goes into the bottom of the meter box. I have 3 50 amp circuits to feed my on-demand hot water heater, and it is just good old Romex across the attic.

Please elucidate so I can increase my level of erudition ;)

If you can read this, thank a teacher.
Because it is in English, thank a soldier!

[Mark Singer]

wheres the dust? No cutting hot dogs on that baby!

[Tyler Howell]

Tyler, let me ask why you decided to use EMT? Was it between an adjacent sub-panel and your disconnect? Was it because you couldn't get into the wall? I am curious since the only EMT around our house and shop is the 3 inch pipe that sticks out of the ground and goes into the bottom of the meter box. I have 3 50 amp circuits to feed my on-demand hot water heater, and it is just good old Romex across the attic.

Please elucidate so I can increase my level of erudition ;)

If you can read this, thank a teacher.
Because it is in English, thank a soldier!
Hey Ken,
I'm a big fan of plumbing as I have ranted about in the past. The run is about 15 ft as the crow flies. I made a right turn to dress it up a bit and avoid the furnace.
EMT is real resistant to harm especially where you are moving heavy equipment and swinging 2x4s. It dissipates a lot of heat and is expandable. ;)

[Daniel Rabinovitz]

Tyler
Very GOOD!
I think that we should add a little basic information for the fellows also.
Tyler is so careful about not nicking the wire, and creating a hot spot.

It is because electricity doesn't "flow through" a wire; BUT rather on the "immediate" (lest someone take me to task) surface of the wire. Simpler - it flows on the surface of the wire.

Hence there is #14 gauge for 15 amp wire.
There is #12 gauge (thicker than #14) for 20 amp wire. and so forth.

A nick creates a vary slight gap in the surface, that the electricity has to flow down and up or around and hence makes other electrical molecules compress around the nick and rub against each other and create heat. Get the wire hot enough and the insulation melts or the wire melts. Try squeezing a 100 people through two exit doors after a woodworkers conference. eh?

Basic, ain't it?

That's all!
Daniel :D

[Ken Garlock]

Hey Ken,
I'm a big fan of plumbing as I have ranted about in the past. The run is about 15 ft as the crow flies. I made a right turn to dress it up a bit and avoid the furnace.
EMT is real resistant to harm especially where you are moving heavy equipment and swinging 2x4s. It dissipates a lot of heat and is expandable. ;)

OK Tyler, sounds good to me, just curious. I guess you ran multiple single conductors since you are not a fan of Romex.

[Tyler Howell]

Thanks Dan, More Knowledge is Power.
That little nick in the insulation from my predecssor had a friend down stream. Just disturbing the wires was enough to get a little short Ckt action. When I heated up the HVAC 30 amp breaker I saw the rockets red glare.:eek: Blew the main, subs main and the HVAC 30amp breaker.
Sorry my camera wasn't ready. The only evidence was a little burned pin hole next to the nick, and the bodily fluids in my pants and shoes:o .
Had my linemans gloves, eye protection and safety shoes all in place (PPE. personal protective equipment). I think I'm going to add Depends to my PPE bag.:rolleyes:
Replaced the whole run with 10 AWG stranded in 3/4" armored liquid tight flex. Was only down for about 2 hours on the steamiest day of the year and most of the work was in the basement. Also replaced the breaker cause it smelled a little funny. (CKT breakers are only guarenteed for one operation by the manufacture).
As long as I was in the box I excersized all of the breakers, torqued all the screw and checked the temps of all the breakers.
Play safe.
http://www.sawmillcreek.org/attachment.php?attachmentid=8590&stc=1

[Ken Garlock]

Tyler
Very GOOD!
....
It is because electricity doesn't "flow through" a wire; BUT rather on the "immediate" (lest someone take me to task) surface of the wire. Simpler - it flows on the surface of the wire.
....
That's all!
Daniel :D

Daniel, what you are referring to to is called skin effect. Skin effect is directly related to the frequency of the alternating current in the conductor. Skin effect really only gets to be a concern at radio frequencies, say several hundred kilohertz and on up. It is a design consideration for microwave systems which often have gold plated circuits to reduce the "resistance" of the conductors.

At audio frequencies, including 60 Hz power lines, the electric field penetrates the entire conductor and skin effect is of no consequence. The flow of electricity is really a movement of electrons from atom to atom, and I have heard estimates of it taking a minute for an electron to move a foot in a wire when we talk about direct current. In the case of an alternating current, the electrons move very little in the wire due to the changing direction of the current flow.

I always shake my head in disbelief when I hear some "audiophile" talking about how good his expensive audio systems sounds with the new $300 cables he just bought. The biggest case of the emperor's new clothes I have ever heard. At the frequencies the human ear can hear, all the currents penetrate the entire thickness of the conductor, and skin effect is of no concern. Basically, wire is wire. You can do just as well with good old 12 gauge rubber covered wire running from your amp to the speakers. Of course this is discussed with religious fervor by some. But, those same people are unwilling to participate in a double blind test of cables.
However, like some other things, size does count. The bigger the conductor the less resistance it has per foot. In modern solid state equipment, the name of the game is to place the speaker cone where you want it when you want it. The best thing you, as the user, can do is to use large cross section wire, say 12 gauge or even bigger, thus minimizing the resistance between the amplifier transistors and the speaker coil. Even here is there is no "free pass," the critics will tell you that you need "oxygen free" copper to do the job correctly, probably a feature of those $300 cables above.....

See Daniel, you touched my pontificate button, and caused me to bloviate ;)

[Tyler Howell]

Hey Ken,

Now I have heard many times"improve your sound? Improve your interconnections". They may have all been salesmen? I do have oxygen free copper in the studio and home theater systems. I did do a sytem set up with a vector voltmeter and could see phase relationship change on same length of wires. doble blind test. No $300.00 speaker wires here:eek: . A little fiber optics cooking at the Howell house:cool: .
Not sure today, but about 15 years ago high voltage transmission lines (50-60 hz) were hollow because of the "skin effect" I got the RF story in school too. But they are nailing this phenomina (sp) with more credit in more areas.
My main concern was less wire(even a little) less capacity.
Major concern of mine is where a cut in the insulation combined with dirt and moisture can develope a short. Or in my case direct short to bare copper conductor.
I've disassemble others work to find strands had been cut to make an AC connection fit:eek: . Yes there was a failure at that spot.



Debate is good gents. I'm hoping the noobeez with think through the process before jumpin in. And some of the veterans do a self chretique (sp) As I said this ain't rocket science but it is a science!;)

[Ken Garlock]

Hey Tyler.

Given two wires, same gauge, same insulation, and same length, you should see the same readings. The phase shift is caused by the inherent capacitance of the wire, this will vary with the type of insulation and its thickness. So, I would expect to see a difference electrically, but the real question is, in a double blind test "can you hear it?" Regarding improving your interconnect, consider the weakest part of the interconnections, the binding posts at each end of the run. Spend big dollars on wire cables and terminate them in connectors that sell for 89 cents at the local supply house(not Rat-Shack). BTW, I like fiber cable, but that isn't it only good between components in a digital format?

Regarding the power transmission cables. Well Tyler, you made me dig out my dusty, moldy, forty year old, field theory text. An example in the text using 1000Hz gives a skin effect depth of 2.09 mm. The depth of the skin effect is inversely proportional to the square root of the frequency, holding other things constant. Digging out the trusty TI calculator. I found that 60Hz current has a skin depth of 8.5 mm or about 1/3 inch. Likewise, 20Hz has a depth of 14.7 mm, or .58 inch, a little over 9/16". So what can we say? Yes the power lines you mention are hollow with good reason, the cost weight, and skin depth. One could say that a wire 2/3" in diameter would do the job, the that is ignoring the expected current flow in amps. Making the hollow cable larger in diameter while maintaining the 1/3" outer wall will give a larger cross section area thus providing for more current flow. Is your "monster cable" a 1/3" diameter(60 Hz) or better yet, is it 9/16" thick to cover the 20Hz condition? ;)

As an aside, I saw a show on the science channel(I think it was) about repairing the big cross country power lines. For the really high voltage stuff, reaching as high as 500,000 volts (yes, half a million), they use a helicopter to deliver the repair man onto the actual cable. Sometimes he can do the repair from a seat on the copter landing gear skid, and sometimes he needs to crawl over onto the line. On the 500KV lines, each conductor is comprised of four smaller cables in a box configuration that is maintained by spacers along the cable. As the copter approaches the cable, the repairman uses a metal rod connected to the frame of the copter to reach out and touch the cable thus bringing the copter up to the 500KV potential. That rod drew about a 3ft. arc during the connection. Man, that copter pilot has a tough job holding the copter about 1 or 2 feet from the cable -- nerves of steel!

Here it is the beginning of the week, and I have aready used up my allocatoin of thinking :D

[Chris Padilla]

Hi Ken,

Nice explanation. Being a EE myself (I know you are a physicist), be careful to separate skin depth and skin effect. :) I'll leave it to you...you are cooking! :)

Also, for the 20Hz...I think you meant 20 kHz. ;)

[John Miliunas]

Good grief, gents! You are truly making me feel inadequate! :o I thought I were doin' purty dern good when I hooked up my 220v equipment and it ran! Without even blowin' nufin' up or even popping a breaker. :rolleyes: "OK, John....Exit stage left..... :o :cool:

[Tyler Howell]

Yea I like good binding posts and RCA plugs too! Gold plated!!! Homie don't play Radio Scrap.
We did some interesting phase testing on cable off the same real (RG214) cut them to the same electrical length and then reversed them end for and and found a phase change,:eek: .
One other instance was pulling all the 214 out of a system and dumping the rest of a thousand foot roll because the dialectric and center conductor moved at a much different rate than the rest of the cable. Amazing world we live in. Have a good week!

[Chris Padilla]

Tyler,

Can you expound how you set up the testing on these cables and how you determined the phase difference? Also, could you explain a bit more on what exactly you mean by phase difference? Did you use a network analyzer or a TDR or something? RG214 is 75-ohm if I recall correctly. Also, simply stating there was a phase difference doesn't tell one much without the frequency or frequencies involved. Also, how much of a difference? :D :D Tough getting all those worms back in the can, eh?? :D :D

[Ken Garlock]

With audio we have a large change in frequency(1000:1) and hence impedance. It would nearly impossible to match source, cable, and load impedances for maximum power transfer, and minimum standing waves on the cable with the frequency moving randomly. Messy :(

Ah Ha! Another problem for the audiophile, reflected power on the speaker cable! Do you think they hear it? ;)

[Steven Wilson]

With audio we have a large change in frequency(1000:1) and hence impedance. It would nearly impossible to match source, cable, and load impedances for maximum power transfer, and minimum standing waves on the cable with the frequency moving randomly. Messy :(

Ah Ha! Another problem for the audiophile, reflected power on the speaker cable! Do you think they hear it? ;)

Well Ken, you might not hear differences in cables but some of us do (BTW, I'm not a fan of Monster Cable, I build my own from Mogami and Belden stock). I'm not very AR for my home system but am somewhat for the recording studios I've setup (two mobile broadcast studios and my own studio). Keeping everything else the same, cables can make a difference. I notice them the most with speakers and the audio cable from the mixer to the amplifiers, also between the main instrument or vocal microphone and the mixer input or A/D converter. For backup instruments and effects patching good, decent (not exotic) wiring works well enough for me. My main signal processing run (mixer to speakers, and main mic input) for my own studio is in the $500 range. Some folk's I've worked with have, IMHO, gone way over the top in wiring (try a 96 track facility wired at $1500/meter - cable bill was 7 figures). I have a good friend, now in Atlanta, that had me listen to some proposed changes to his studio. He was going for a decent stereo input chain (2x5m), and short runs from his mixer to amps and monitors (2x2m). So, about 14 m at $1500/m, which was a bit extreme for me. You could however hear a subtle change in imaging and lower end tightness on previously mixed stuff and a very noticeable change in microphone response in the Neuman U87's we tried. For my needs the change wasn't cost effective but my friend thought it was for his studio. For this test, I didn't see the cables and didn't know which ones were running. For material I used a variety of material that I was familiar with.

[Chris Padilla]

I find it fascinating that people do claim significant differences in audio dependent upon the cable and/or interconnects. I wasted a day at work once pushing some equations around and doing lots of reading in my EM and Physics books to try and figure out some kind of parameter or parameters that might actually make a difference. Sink effect/depth was the major one I was fiddling with (so-called AC resistance) along with DC resistance.

Most electronic savvy folks know that AC circuits are incredibly sensitive to outside influences that can dramatically affect various parameters of a signal as it meanders about a conductor. Even the elements of the amplifier itself can cause problems with other elements of the amplifier.

Cool thread...sorry, Tyler...it happens! :)

[Chris Padilla]

With audio we have a large change in frequency(1000:1) and hence impedance. It would nearly impossible to match source, cable, and load impedances for maximum power transfer, and minimum standing waves on the cable with the frequency moving randomly. Messy :(

Ah Ha! Another problem for the audiophile, reflected power on the speaker cable! Do you think they hear it? ;)
I'm happy to get messy, Ken. At the frequency range of hearing, matching impedance isn't all that difficult and it would take quite a length of cable to start talking transmission lines but your point is well made.

[Ken Garlock]

I'm happy to get messy, Ken. At the frequency range of hearing, matching impedance isn't all that difficult and it would take quite a length of cable to start talking transmission lines but your point is well made.

Of course you are right, Chris. Heck, when a full wave at 100 Hz is 3,000,000 meters, a little over 1864 miles, we are talking things that only happen on a computer, or outer space :) I think I will stick with things I can see, like a half wave at 50 MHz....

I think I will drop out of this thread that I kind of hi-jacked, sorry Tyler. I don't want to be accused of starting and maintaining a religious debate :D

The nice thing about this forum is that we can all agree to disagree, and go away happy :)

[Tyler Howell]

Thanks guys Got a chance to relive some theory courses. Chris I'll dig up some test procedures for you.

Thanks for Looking.;)

[Daniel Rabinovitz]

It's amazing what will happen if some klutz comes along and says that electricity flows along the surface of a conductor and not through it.. EEEEE Gads!
But I was able to renew some old memories concerning theory, it's been a long time.
I bow to the wisdom of Ken, It's been great.
I'm sure the guys or gals that want to mess around with 220v wiring in their shops will take heed, that we have some experts around that really "know their stuff".
I always thought that:
DC - went in one direction
AC - went in two directions
High Tension - went in any direction it darned well pleased.
But keep your fingers out of light sockets.
And don't touch spinning blades or lightning will strike you.
Daniel :D

[Greg Heppeard]

Thanks for reminding me why I got out of electronics.... :D lmao....all of this debate overloaded my synaps circuitry. All I wanna know is, what's the basic resistance of kd red oak 1" x 1" x 1" @ 8% moisture content? :eek:

Just kidding guys...you got me thinking again, guess I needed the jump start.