Wiring on power pole

[Shannow]

Originally Posted By: turtlevette
Originally Posted By: Brad_C
Originally Posted By: turtlevette

All residential is single phase. Unless you have some massive place with waterfalls that need greater than 10hp pumps.


There are loads of residences here with 3 phase.. like.. mine, and every house within a block either way of mine. Not everybody lives in a backwater.

My 3hp bore pump is 3 phase, as is my A/C compressor.


Really?

Low HP 3 ph motors are expensive and unnecessary. Most of he worlds residental is since phase. I suspect you don't really know what you have.


Really, you can tell that over the internet ?

Brad_C has a fairly reasonable technical bent...I'm pretty sure he has an idea what he's got...especially as he would be paying the bills.

Plenty of Aussies have three phase, three meters (4 with off peak hot water).

 

[Shannow]

Originally Posted By: turtlevette
Originally Posted By: MolaKule

What they use around here is "copper-clad" a steel wire with copper cladding:

http://www.southwire.com/support/copper-clad-steel-gets-theft-deterrence.htm


[censored]. Most everything in service is copper or aluminum.


Dunno, the type of product that Molakule raised seems fairly commonly available, and has been for 100 years.

http://copperweld.com/en/products/metals/ccs.html

Grounds on the wooden poles around my district are all galvanised steel, purely for the theft aspect that Molakule raised.

 

[Brad_C]

Originally Posted By: turtlevette

Low HP 3 ph motors are expensive and unnecessary. Most of he worlds residental is since phase. I suspect you don't really know what you have.


(Bugs Bunny Voice) "He don't know me vewwy well". Trust me, I know how my house is wired. I re-balanced the loads after I bought the place to reduce the imbalance in the neutral because load profiles have changed in the 40 years since it was built. I replaced the single phase compressor in my heat pump A/C with a three phase unit to reduce power factor issues caused by an increased condenser efficiency, and I re-built my bore pump about 2 years ago. I know a delta wired three phase motor when I see one and I've wired a few.

In fact, every house I've ever lived in (that's 6 to date) has been wired three phase. [censored] my rental Apartment in Dubai had 3 phase. My Grandmothers 60 year old "war service" house was single phase, but that's certainly in the minority.

Like I said, not everybody lives in a backwater.

 

[BRZED]

Originally Posted By: Shannow
Originally Posted By: turtlevette
Originally Posted By: Brad_C
Originally Posted By: turtlevette

All residential is single phase. Unless you have some massive place with waterfalls that need greater than 10hp pumps.


There are loads of residences here with 3 phase.. like.. mine, and every house within a block either way of mine. Not everybody lives in a backwater.

My 3hp bore pump is 3 phase, as is my A/C compressor.


Really?

Low HP 3 ph motors are expensive and unnecessary. Most of he worlds residental is since phase. I suspect you don't really know what you have.


Really, you can tell that over the internet ?

Brad_C has a fairly reasonable technical bent...I'm pretty sure he has an idea what he's got...especially as he would be paying the bills.

Plenty of Aussies have three phase, three meters (4 with off peak hot water).


Gentlemen, I beg of you.

 

[JHZR2]

What's on the pole? If its like what Ive observed around here, it is:

very top: three phases at a high distribution voltage, say, 11-13.8kVAC. Three wire.

Middle: Intermediate voltage from lower level substations, say, 4160VAC, four wire.

Lower: Three phase wiring in little triple-wire holders (still has appropriate spacing for standoff/creepage/clearance). From these, transformers are connected to one of the three phases. I believe these are 480VAC distributions to feed industrial applications.

Huge industry may get 4160 or higher. 4160 at 4000A is in the 20's of MW. So most large facilities that have their own switchgear and transformers can deal with 480VAC 3ph, as a 4000A breaker there is still a few MW, which is a LOT of power.

So your domestic use pole transformers take one of the three phases from one of the higher distribution voltages, and transform to 240V split-phase. Split phase means that there is a "center point" ground in the transformer. Since voltage is a potential (think like air or water pressure), it can be mathematically divided. That's what we have. Potential from conductor A to B is 240V (transformed from 480VAC or higher, off of one of the phases), and the middle point ground to either leg is 120VAC.

Transformers like this:

http://www.geindustrial.com/products/transformers/single-phase-pole-type

Then some industrial applications use 208VAC three-phase. Since the Line-line = sqrt(3)* Line-Neutral, then what you get is that each phase is 120VAC, with the three phase voltage being 208VAC as a result. Some equipment is dual-rated to take 240VAC or 208VAC, the purpose being to allow either type of power. Note you cannot make 240VAC domestic split phase power (i.e. take two 120V conductors and use them together to get 240VAC) from 208VAC three phase without some other claptrap, because each 120V conductor is 120 degrees out of phase.

The calculation of three phase voltage characteristics is precisely why high school pre-calculus math is important. This isn't more difficult than high school math, playing with sine waves, which sadly, many are not capable of doing and comprehending.

So long story short, you have some higher voltage conductors making longer runs (higher voltage = lower current so more capacity on a finite size wire), then they get stepped down to intermediate voltages, and locally, transformers pull from one of the three phases to make 240VAC split phase, with neutral, so that domestic users can power bigger devices.

 

[BRZED]

Again, very helpful. Thank you for taking the time.