Electricity: Ground?

[Duane Attaway]

On Mon, 15 Sep 2003, Brian Kelsay wrote:

> Your house can still meet code without having grounded sockets.  BUT, if
> you install three prong "grounded sockets and they are not grounded, you
> just violated code.  If the inspector puts his little circuit detector
> in your socket and it passes the test (green light) then you are up to
> code.  I know this because I installed three-prongers and didn't ground
> them.  I went to sell the house and we filled the ground hole w/ caulk
> and all of a sudden we were at code.  Brilliant.
> 
> I think you can run a jumper line from the negative side (white) to the
> ground and it will make the socket pass the plug test.  All the white
> wires in your electrical box run to a common block and that block is
> grounded.  Now will it protect the stuff plugged in to a true three-wire
> ground the same?  Don't know, but it will supposedly pass the test.  
> Where you don't want to screw around is in the kitchen and the bath.  
> You're around water remember?  In there, make sure you run three-wire
> and put in one of those outlets with the breaker/reset.  You need at
> least one in the kitchen and one in the bath is a good idea too.

The house should be safe as long as the connections are tight.  Your
computer has built in surge protection as well as your power strip.  Some
of the better UPS units have inverter circuitry that completely isolate
the mains from your system.  I wouldn't worry about old wiring affecting
the integrity of your computer equipment.  Unless you live on top of a
hill and its starting to sprinkle...

Please don't make any modifications to the outlets unless you are going to
update the entire system.  Uniformity of a house's electrical system makes
electricians and inspectors happy.  That makes your insurance adjuster
happy when your house burns down from a chimney fire and doesn't have to
blame that on your wiring.  Or something like that.

The only reason why we have grounded outlets is due to a couple of
reasons.  Higher voltages like to be free.  Larger appliances, such as
refrigerators, stoves, washers, and driers, have large surface areas that
may absorb some of the electrical charge.  This may release current into
someone who touches it, or worse, enough of it may take a path by a weak
connection to another appliance creating a possible fire hazard.

There are a few ways this electricity can leak.  Enamal insulation in
motors tends to break down over time due to corona disharge from
inductance.  Moisture is another common surprise among humans who use
these appliances.  Small amounts of measurable current may charge the
chassis.  A ground return line prevents this buildup and protects nearby
objects.

A grounded appliance contains electrical failures and helps them to
prevent catastrophic damage.  Like fires.  If your computer has a leaking
transformer in the power supply, a ground path will collect this discharge
before it runs away and starts heating up other cables not intended for
power distribution, like your speaker wires.  Rather than heating the
wrong cables, your power cable ground wire is the safe return of current
back to the breaker box.  Breaker is tripped while your computer case does
not soar to 120VAC.

Non grounded, but polarized outlets aren't so bad either.  The large spade
on the outlet is your neutral line (white wire) and the small one for the
"hot" (black wire.)  The neutral line is supposed to be zero volts with
reference to the ground you stand on with your bare feet.  If your wiring
is good, this works rather well.  But large appliances can build up a
voltage drop and can give you a buzz when you touch the case.  That's why
we moved to grounded outlets.  That ground is supposed to not be a
functional part of the circuit, but a backup just for safety purposes.  
Electrically, the ground *is* the neutral wire at the breaker box, but it
is the one wire that we are supposed to count on when we don't want to get
shocked.

Higher voltages of 480 volts and 14,400 volts and higher that I work with
*require* a ground system.  Voltages this high have a life of their own.  
Capacitances, corona discharge, magnetism, natural resistance, breakdown
of insulators, ultraviolet light, and flashovers on a regular basis may
give you a real appreciation for what grounding can do.  Sometimes
breathing in the vicinity of a 480 volt outlet can cause a flashover.  I
have seen the brightest flashes of light due to that fact.  My experience
has shown me that ANSI approved safety glasses are a must around anything
above 240 volts.

Voltages of 150,000 volts just like to jump out of sharp corners at random
times because they feel like it.  That's when you like to be on the other
side of a grounded wall of steel.

This is why most people like to leave electrical work to an experienced
electrician:

http://dattaway.org/powerline-explosion.jpg

High voltage is fun.  Just don't do this at home.