Holy smokes! where to start on this post???

It doesn't require less voltage, it's supposed to handle more current and can handle bigger voltage.
Absolutely 1/2 true
The larger gauge (smaller number) wire can carry more current.
The voltage rating has nothing to do with the gauge of the wire - its a function of the type of insulation on the wire.

Plus there is more wire meaning more resistance on longer runs of wire.
Absolutely 100% false
There is a 100% linear relationship between the length of the wire and its total resistance. For example 10 gauge copper wire has a resistance of ~1 ohm per 1000 feet of length. 2000' of this wire will have ~2 ohms restance.

 

A wire's current rating also depends on the length of the wire. The longer the wire, the thicker it needs to be able to pass the same amount of current (safely).

 

In other words, Longer wire has more resistance, so it needs to be thicker to compensate and allow the same current as the shorter wire?

 

Close enough. You will have a voltage drop on longer runs of wire so the most common thing to do is just run a larger gauge of wire for the run.

 

you are only discussing the length and thickness of the wires but are not saying anything about the insulation of the wires themselves and how will affect the rating or conductivity.

http://www.usawire-cable.com/pdfs/WIRE%20KNOWLEDGE.pdf

 

The insulation has no effect on the current carrying capabilities of the wire.
That doesn't mean the insulation isn't important. The first issue for insulation is the voltage rating it has. When we are talking about 12 volt systems wire with insulation having a 600 volt rating is more than adequate. The other issue is what the insulation is made of. Some have properties to resist breakdown in hostile chemical environments or stand up to very high temperatures. Where you are using the wire and what it will be exposed to will determine its insulation properties.

 

Look at the table in the second page,I do not know what you do for a living,I am a master electrician.
http://www2.schneider-electric.com/r...0600DB0103.pdf

 

That has nothing to do with the absolute current capacity of the conductor. Those are NEC guidelines about how well a cable can tolerate heat before becoming a safety issue. With lesser insulators, you see a melting risk or permanent effects due to heat cycling at lower current. With better insulation you can heat the conductor up more without as much risk of insulator damage.

 

Sorry pr, but I don't see a single thing in that link that contradicts a thing I said. . . Actually it has some very good information in those tables showing a lot of characteristics of the different types of insulation.


btw never a good idea to make an accusatory statement/question if you don't know the answer to it.

 

I wouldn't hire him as an electrician. LOL.

 

Maybe you are not reading the table right.Take for example #8 copper wire TW insulation 40 amps,same wire with ThhW is 50 amps and with Rhh is 55 amps.It does not change the characteristic of the wire itself,but with a better insulation you can use a smaller wire.

The insulation of a wire does not affect the resistance of the wire. Resistance does, however, determine how much heat is needed to burn the insulation. As current flows through an insulated conductor, the limit of current that the conductor can withstand depends on how hot the conductor can get before it burns the insulation. Different types of insulation will burn at different temperatures. Therefore, the type of insulation used is the third factor that determines the current rating of a conductor. For instance, rubber insulation will begin deteriorating at relatively low temperatures, whereas varnished cloth insulation retains its insulating properties at higher temperatures. Other types of insulation are fluorinated ethylene propylene (FEP), silicone rubber, or extruded polytetrafluoroethylene. They are effective at still higher temperatures. From the NEC 2012 code book.

 

No, we're all reading the table properly. You claimed the conductor handles more current - it does not. Simply it's safe to carry more current with one type of insulation versus another.

BTW mr_white, an electrician is not the same as an electrical physicist.

 

I am aware.

 

Not surprised, residential electricians are stupid.

There is no way you could do control and power wiring in the panels I build.

How would plastic insulation varying on MTW or THHN/ TFFN wire allow it to conduct better?

 

If you are talking about me I never work on a house in my life.Al i did was industrial work, power plants, refineries,airports and water treatment plants.
on the treatment plant did work from 12 V to 13,200 volts.We had five 2,000 hp motors
three of them were controlled with VFD's that were 20 ft long (Robicon Brand).

If you know so much explained to me what is an open delta connection in a transformer bank and why would you used it.