On Mon, 24 Mar 2014 20:48:16 -0400, "Mr. Luddite" wrote:

On 3/24/2014 8:08 PM, wrote:
On Mon, 24 Mar 2014 18:47:29 -0400, "Mr. Luddite"
wrote:

On 3/24/2014 5:40 PM, wrote:
On Mon, 24 Mar 2014 16:53:46 -0400, "Mr. Luddite"
wrote:

I understand and I didn't say it was accurate. However, as the other
poster pointed out there is sometimes some confusion as to what a home
service is called since you *do* have two hot legs 180 degrees out of
phase. The "split phase" isn't a reference to how a motor is wound in
this case. It's a reference to the center tapped, 240v service
producing two hot legs 180 degrees out of phase referenced to neutral.

The terminology used to describe it has been a subject of debate for years.




That is why code officials are trying to straighten it out every
chance they get ;-)


I am not an electrician. I've found over the years that terminology
used in the NFPA codes sometimes differ somewhat from what we use in
engineering even though we are talking the same thing. I also sometimes
found that some industrial applications are not defined or even covered
in the code book. If an issue arose that was questionable I had a EE PE
check it over and stamp the final power and control system drawings.

Last winter I got involved in a project building a performance venue
stage and it's wiring. The building had a dedicated 3 phase power
distribution panel that had previously been used for when the building
had been a large machine shop. I used it to distribute several 120vac,
20 amp feeds to the stage, overhead stage lights, PA system, house
lights, etc., but because I am not up to speed on current code
requirements for things like ground fault protection devices and another
new one that I can't remember the name of, I asked a friend who has been
a licensed master electrician for 26 years to review what my plans were
to make sure I didn't violate any codes and to ensure it was safe to use.


There is not much in the way of requirements for GFCIs in commercial
venues other than outdoors, commercial kitchens, bathrooms and
vending machines.
The other thing I assume you mean is AFCI and that is pretty much a
just residential thing.

As far as residential house power is concerned, to me it is single phase
(at whatever high voltage is used locally) up to the primary of the
transformer. The secondary has two "hot" legs from the center tapped
transformer that are 180 degrees out of phase with each other referenced
to neutral or ground. In my world that is two phases, "zero" and "180"
relative to neutral or ground. :-)

The primary going down your street is usually called "medium voltage"
(600v.. High voltage is when you start getting over 35-38kv. That is
generally NESC (National Electrical Safety Code) territory tho, not
NEC. That is the set of rules that PoCos follow.


The high side (medium voltage) going down the poles in our area is
13,500 volts ... maybe higher. The service to our house is via high
voltage underground cable for about 700 feet to the step down
transformer that is on a pad closer to the house. From there it feeds
the power panels in the house and another panel in the horse barn again
via underground conduit and wiring.

The medium voltage cable is similar to a coaxial audio cable except much
bigger. Center conductor/insulation/ground shield.

Shortly after we bought the house a short developed in the underground
line. It sounded and felt like a bomb went off somewhere. The power
company sent a guy down and he attempted to replace the fuse up on the
pole using the bucket lift on the truck. (it's only a 15 amp fuse). My
son and I were watching him from a distance and as soon as he pushed the
new fuse in with a fiberglass pole they use there was another explosion
and a huge flash. I called up to the guy in the bucket to see if he was
ok and he just laughed. Said he was "used" to it. Scared the crap out
of me.

They used a "thumper" which is similar to a time domain reflectometer to
determine where the underground cable was shorted. Fortunately, they
were able to pull a new cable through the underground conduit by hooking
it onto the old cable and then pulling it through using the utility
company truck. Otherwise, they were going to have to dig everything up.

One night last summer what sounded like a 105mm round went off in our front yard. I thought it was a
transformer on a pole. The lights went out. I called the electric company and went back to bed.

The next morning I awaken to the sound of lots of equipment outside. It turns out the transformer
did blow, but it was in my front yard, not on the pole. I'll have to admit they did a good job of
repairing my yard.