Electrical Advice

[jsburger]

[...] reason being is electric current travels along the out side of a wire , a antenna ,,wire terminal ,,,,or metal object , by soldering the ends you bring all these lose ends back into one [...]

JMO

Reasonable people may differ on the pros/cons of soldering vs. crimping... but please take the "skin effect" out of the mix for our conversation about AC power... At 60Hz, AC is effectively DC -- there is no skin effect in home wiring -- it is all about the cross sectional area and material used for the conductors...

73 Ely

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NOPE

Many people dont believe any thing that doesnt come with a link so I found you one.


So skin effect would be observed on cables with radius greater than 9.2 mm which means 18.4 mm diameter (3/4 inch) (or a 266 m² cross-section), which is very close to AWG(7\0), a gauge qualified to carry hundreds of amperes (while a domestic installation carries no more than 50 A). Since most cables for home are less than that, the skin effect is often and justifiably neglected in home electricity applications.

Also, the skin depth is the distance from the surface of the conductor to where the current density is damped to less than 1/e (36%) of its surface value. So in fact you would need even more diameter to observe the center of the cable having no current.

Regarding the choice between stranded and solid cables, solid cables are often preferred for home wiring for different reasons including cost, size, durability. Those have already been discussed in here :

https://electronics.stackexchange.com/q ... res/219122

----------------------


Like the site says,,,, it is neglected ,,,,,in house wire not that it doesnt exist ,, along with the magnetic resistance .

Better check your source. Those numbers are not even close for 7 Gauge wire.

Neglected is probably not the right term when it comes to house wiring. Eli and Ed are correct. It has no useful place when discussing house wiring. Skin effect basically does not exist at 60Hz in house wiring.

To quote Ed's Wiki link... "At 60 Hz in copper, the skin depth is about 8.5 mm." That is 0.335". 12 Gauge wire is 0.082" in diameter. That in effect negates skin effect in house wiring.

0 Gauge wire is 0.325" in diameter so you would have to go to that gauge wire or larger before skin effect starts to show up at 60Hz.

[EliWalton]

This is fun, but I think we all agree the OP should toss the cord reel?

73 Ely

[jsburger]

This is fun, but I think we all agree the OP should toss the cord reel?

73 Ely

Yes it is!!! What is your call sign? I also agree that the OP should ditch the reel.

Here is another point. Many people decry extension cords and say they should be as short as possible. If you buy a quality 12 Gauge extension cord (I make my own so I know what it is made with) with 20A quality connectors on the ends what difference does it make over plugging the SS into a 20A circuit wall plug wired with 12 Gauge wire from the panel? You have just extended the house wiring by the length of the extension cord.

Another thing, a DEDICATED circuit is not necessary. My shop has 4 20A circuits for the outlets for the tools. Two have two double outlets each. One has 4 double outlets (I know, probably not code) and the other one has 3 double outlets. All were installed with higher quality 20A outlets. Don't go cheap with electricity. Multiple tools are plugged into the same circuit. There is almost never a time that more than one tool is running on any given circuit. However, when there is there is never a problem. Start up current is way higher than running current even under load. Unless you can figure out how to turn two machines within a millisecond of each other you will not pop a breaker if you have proper wiring. DO NOT compromise on your wiring!!!

Having said all that if your machine pops the breaker with proper wiring then look at the machine.

[Ed in Tampa]

This is fun, but I think we all agree the OP should toss the cord reel?

73 Ely

Yes it is!!! What is your call sign? I also agree that the OP should ditch the reel.

Here is another point. Many people decry extension cords and say they should be as short as possible. If you buy a quality 12 Gauge extension cord (I make my own so I know what it is made with) with 20A quality connectors on the ends what difference does it make over plugging the SS into a 20A circuit wall plug wired with 12 Gauge wire from the panel? You have just extended the house wiring by the length of the extension cord.

Another thing, a DEDICATED circuit is not necessary. My shop has 4 20A circuits for the outlets for the tools. Two have two double outlets each. One has 4 double outlets (I know, probably not code) and the other one has 3 double outlets. All were installed with higher quality 20A outlets. Don't go cheap with electricity. Multiple tools are plugged into the same circuit. There is almost never a time that more than one tool is running on any given circuit. However, when there is there is never a problem. Start up current is way higher than running current even under load. Unless you can figure out how to turn two machines within a millisecond of each other you will not pop a breaker if you have proper wiring. DO NOT compromise on your wiring!!!

Having said all that if your machine pops the breaker with proper wiring then look at the machine.

I agree with what you said, HOWEVER the extension cord prohibition is correct, in probably 99 percent of cases. Most " construction " looking extension cords are cheap 18-16 gauge wires and even the ones that are 12 gauge are so cheaply made that there is a huge voltage drop at the plugs connectors.

I have probably 6 cords marked as 12 gauge but only two are the quality needed to carry 20 amps with minimal voltage drop. The others get hot around their connectors when 8 to 10 amps are drawn through them. 3 of them are marked 12 gauge but they are smaller than that, my guess is they are chinese 12 gauge which equals about 16 gauge

I also noticed the older an extension cord gets the higher the voltage drop occurs in it. Unlike house wiring that nearly never moves extension cords get moved, flexed, stepped on, smashed, twisted, stretched, nicked and cut all the time. Each one of these effect the cords ability to carry the rated amperage with minimal voltage drop.

Unless a person knows for sure the quality, age and condition of the extension cord they should not use them on machines like the Shopsmith.

In my case I observed a MARKED difference in the operation of my Shopsmith when I replaced the manufactures cord with a very high quality 12,gauge cord. I want to say it was Day and night difference but that is probably an overstatement. Let me put it this way I would never go back to the official Shopsmith line cord.

You are right if you made your own and know what went into you you can consider as nothing less than an extension of the home wiring.

[Hobbyman2]

Reasonable people may differ on the pros/cons of soldering vs. crimping... but please take the "skin effect" out of the mix for our conversation about AC power... At 60Hz, AC is effectively DC -- there is no skin effect in home wiring -- it is all about the cross sectional area and material used for the conductors...

73 Ely

=================
NOPE

Many people dont believe any thing that doesnt come with a link so I found you one.


So skin effect would be observed on cables with radius greater than 9.2 mm which means 18.4 mm diameter (3/4 inch) (or a 266 m² cross-section), which is very close to AWG(7\0), a gauge qualified to carry hundreds of amperes (while a domestic installation carries no more than 50 A). Since most cables for home are less than that, the skin effect is often and justifiably neglected in home electricity applications.

Also, the skin depth is the distance from the surface of the conductor to where the current density is damped to less than 1/e (36%) of its surface value. So in fact you would need even more diameter to observe the center of the cable having no current.

Regarding the choice between stranded and solid cables, solid cables are often preferred for home wiring for different reasons including cost, size, durability. Those have already been discussed in here :

https://electronics.stackexchange.com/q ... res/219122

----------------------


Like the site says,,,, it is neglected ,,,,,in house wire not that it doesnt exist ,, along with the magnetic resistance .

Better check your source. Those numbers are not even close for 7 Gauge wire.

Neglected is probably not the right term when it comes to house wiring. Eli and Ed are correct. It has no useful place when discussing house wiring. Skin effect basically does not exist at 60Hz in house wiring.

To quote Ed's Wiki link... "At 60 Hz in copper, the skin depth is about 8.5 mm." That is 0.335". 12 Gauge wire is 0.082" in diameter. That in effect negates skin effect in house wiring.

0 Gauge wire is 0.325" in diameter so you would have to go to that gauge wire or larger before skin effect starts to show up at 60Hz.

======================


It didnt say 7 awg it said 7/0 awg there is quite a difference , in order to see no voltage in the core.

pretty sure the training we had described it the same way,, .

At any rate I never said Ed was wrong.

[Hobbyman2]

7/0 cable would be 0000000 awg

[Hobbyman2]

This is fun, but I think we all agree the OP should toss the cord reel?

73 Ely

================






Ya got to keep these old guys on their toes or they forget a lot!!





Here is a link to Beldon co.

it seems there have been numerous discussions on how skin effect works ,,.

http://www.belden.com/blog/broadcastav/ ... quency.cfm



Basis:
Depth at 20 kHz = 18.4 mils (.0184 in.) Radius x 2 = 36.8 mils (.0368 in.) Diameter
Amount of conductor used at 20 kHz, based on conductor size
Conductors Diameter % of conductor used
24 AWG 0.024 100% at 20 kHz
22 AWG 0.031 100% at 20 kHz
12 AWG 0.093 75% at 20 kHz
10 AWG 0.115 68% at 20 kHz


@ 60 hz ?.

[jsburger]

This is fun, but I think we all agree the OP should toss the cord reel?

73 Ely

================






Ya got to keep these old guys on their toes or they forget a lot!!





Here is a link to Beldon co.

it seems there have been numerous discussions on how skin effect works ,,.

http://www.belden.com/blog/broadcastav/ ... quency.cfm



Basis:
Depth at 20 kHz = 18.4 mils (.0184 in.) Radius x 2 = 36.8 mils (.0368 in.) Diameter
Amount of conductor used at 20 kHz, based on conductor size
Conductors Diameter % of conductor used
24 AWG 0.024 100% at 20 kHz
22 AWG 0.031 100% at 20 kHz
12 AWG 0.093 75% at 20 kHz
10 AWG 0.115 68% at 20 kHz


@ 60 hz ?.

As I said in a previous post...

To quote Ed's Wiki link... "At 60 Hz in copper, the skin depth is about 8.5 mm." That is 0.335". That is 4 times the diameter of 12 Gauge wire which is 0.082" in diameter. That in effect negates skin effect in house wiring.

0 Gauge wire is 0.325" in diameter so you would have to go to that gauge wire or larger before skin effect starts to show up at 60Hz.

[Hobbyman2]

I dont disagree ,,,

My point to the issue was,,,,, until the resistance reaches a certain load the current is drawn from the outer skin of the wire.

A LED bulb doesnt have the resistance to draw from the center.

A dragging motor will need more electric and more electrons ,,needing more of the conductor ..

Thats all I was saying.

I agree with ya ,,, only issue I have on this skin effect ,,,,,,is what sort of tester did they use to find out there was no current in the center of the wire.

Was never taught this,,,,, or how any one can say they can get a reading from a center of a wire with out touching the surface some where some how.

The end of a wire is part of the surface

I have had that hang up since high school.

[EliWalton]

I dont disagree ,,,

My point to the issue was,,,,, until the resistance reaches a certain load the current is drawn from the outer skin of the wire.

A LED bulb doesnt have the resistance to draw from the center.

A dragging motor will need more electric and more electrons ,,needing more of the conductor ..

Thats all I was saying.

I agree with ya ,,, only issue I have on this skin effect ,,,,,,is what sort of tester did they use to find out there was no current in the center of the wire.

Was never taught this,,,,, or how any one can say they can get a reading from a center of a wire with out touching the surface some where some how.

The end of a wire is part of the surface

I have had that hang up since high school.

I don't know where to start... so I won't...

73 Ely