🚀 go-pugleaf

robf@mcs213k.cs.umr.edu (Rob Fugina) writes:

>In article <kJhTxoE@quack.sac.ca.us> mrapple@quack.sac.ca.us (Nick Sayer) writes:
>>Now ground and neutral clearly are not the same thing. I would
>>expect negative side effects were I foolish enough to hook
>>a light bulb between hot and ground.

Actually, the bulb will work fine.  By using a pig tail lamp (100w) its a good
idea to make sure that the bulb works fine between hot and ground - as
this checks out the ground path to make sure it is a good connection.
Note that is the circuit being tested is a gfi (ground fault interrupter)
this will (should) cause the unit to trip.

>Ground and neutral are exactly the same thing.  If you were to trace the
>wires back to your breaker box, you would find bare wires (ground) and white
>wires (neutral) both connected to a grounding strip.  The hot wire's potential
>varies from ~170V above ground to ~170V below ground.  The two wires that come
>from the pole are both hot, BUT, the sine waves are 180 degrees out of phase
>with one another, so when one is at +170, the other is at -170, and if you
>connect something to those two, you will have a 340V sine wave.  (values are
>peak, not RMS...RMS would be about 120 and 240).

If you check a copy of the NEC (National Electric Code) you will find out
that neutral and ground are not the same thing.  
Note that these comments really only apply to the United States code.

Yes it is true (at least in the Chicago area) that the neutral wire upon
entrance to a building is to be "bonded" or tied to the chasis of the
circuit panel.  This is usually done via a small bonding lug that comes
out of the neutral bus bar and gets connected to the chasis of the panel.
A wire then connects from the neutral bus to the street side of the water
pipe (if metallic) or to a series of ground stakes.  This is the ONLY
place that neutral and ground should be in common in the building.

The emt (conduit) or bx sheath, or ground wire of romax (etc.) is not
intended to be a normal current carrying circuit.  It is there as a
safety ground such that if an appliance fails (loose wire, meltdown, etc)
the ground will short out the fuse or breaker and stop any further problems.
The neutral wire is intended to be a normal current carrying circuit
(is sometimes called the return path - although in a.c. its ...).

If you attach a neutral wire to ground anywhere else in your building, 
you can create ground loops which I wont go into here.

>MY QUESTION is, if you don't have 3-wire connections in your house, why
>can't you connect the white wire to the ground lug and conuit/boxes, etc???

A very dangerous idea. Besides being illegal (against local and national codes)
it could prove very dangerous.  Many appliances (like washers & dryers)
have their chasis tied to earth ground.  If you tie the neutral wire to
the ground lug on the outlet, you have essentially tied the chasis to 
neutral.  Because the neutral wire is current carrying, it is possible
that due to resistance in the wire (IR drop) and/or poor connections that
a voltage drop may exist between the neutral at the outlet and your circuit
panel.  Now if someone (like a small child) brushes up against the chasis and 
happens (and it does happen) to touch a water pipe - a nice shock can
be had!

Electrical work is really pretty easy stuff.  And because engineers and techs
have an understanding of electronics - they often think that wiring a house
is the same.  The problem is that there are code laws out there to protect
us from unforseen and misunderstood problems.  If you are not aware of these
practices - PLEASE contact someone who knows.  Like a licenses (but not
necessarily union) electrician.

If you dont know what your doing, don't.

-- 
===============	regards   'mark  =============================================
Mark Ahlenius 		  voice:(708)-632-5346  email: uunet!motcid!ahleniusm
Motorola Inc.		  fax:  (708)-632-2413
Arlington, Hts. IL, USA	 60004