On Thu, 06 Apr 2006 23:02:15 GMT, "Pop"
wrote:
"LurfysMa" wrote in message
.. .
Can anyone explain to me the electrical terms "neutral",
"ground",
"line", and "load"?
HOT: Power coming into the circuit from the electric company.
The HOT wire goes directly back to the circuit breaker in your
box and is almost always black color.
A meter would read 110Vac on it. Or 220,. depending on the
type of power/country, etc.. I'm assuming US since the
colors/terms you give are US terms.
NEUTRAL: This is the "return" path for electricity, back to the
electric company.
HOT and NEUTRAL are necessary for any electrical circuit to work
correctly and safely.
GROUND/EARTH: This is also called EARTH. And that's just what
it is. It's a wire that goes back to the ground via your breaker
box. It literally connects to the ground; the dirt around the
rod driven into the ground outside your electrical service.
While GROUND will function as a NEUTRAL, it is against codes and
UNSAFE to use it for a NEUTRAL. The GROUND is there so that if
anything goes wrong, housings, cabinets, etc., do not become
energized and dangerous to the touch. Or start fires, etc..
The EARTH wire is either green insulated, or more often just a
bare, uninsulated wire.
LOAD: That's the piece of equipment being run with the
electricity. In a circuit with a light bulb, the light bulb is
the LOAD. The HOT probably goes to a switch, then thru the
switch and to one of the bulb's connections (the center one for
an incandescent bulb). The other side of the bulb connection,
the threaded part, has the NEUTRAL connected to it, and completes
the circuit from the LOAD, back to the breaker box.
So, the LOAD is the light, motor, whatever the electicity is
powering.
Ok, I think I get it.
LINE = the wire from the circuit box. The hot wire.
NEUTRAL = the wire back to the circuit box to complete the circuit.
LOAD = the wire from the switch to the light bulb fixture (the load).
GROUND = a wire to the earth or some very large electricity sink.
So, in a standard toggle switch for a light:
1. The line wire goes from the circuit box to the switch.
2. The load wire geos from the switch to the light fixture.
3. The neutral wire goes from the light fixture back to the circuit
box completing the circuit.
Since a standard toggle switch does not need any power to work, it is
wired in series with the light.
These programmable switches need power for their own operation. They
have two choices. I am ignoring the ground wire. Both of these
scenarios probably need a ground for safety, but not for the basic
operation.
1. They can place their own "load" in series with the light. This is
the simplist installation. It only required 2 wires -- line and load.
But it has the disadvantage that if the light burns out, the circuit
is broken and the switch loses power, which means it can't keep time,
for instance. This is how the 034 works. This is also why the 034 can
be used as a replacement for any standard toggle switch.
2. They can place their own load in parallel with the light. This
required one more wire in the junction box -- the neutral to have a
way to keep current flowing through the switch itself even if the
light bulb burns out or is replaced. This is how the 035 works and it
why it cannot just replace a standard toggle switch.
Is that correct?
It would appear that in order to use the 035, you need all three
connections: HOT, NEUTRAL, and EARTH or GROUND.
If the GROUND isn't already there, it would have to be added
in order to use the 035. Because you don't see the GROUND/EARTH
wire, don't assume it's not there. An electrician would be able
to tell quickly, though.
This is NOT a diy job for you, BTW. Either use an exact
replacement, or call in a contractor to do it right.
I don't plan to do this myself. I just wanted to understand it.
Thanks for the help.
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