Neutral v Ground?

[LurfysMa]

Can anyone explain to me the electrical terms "neutral", "ground", "line", and "load"?

I have an Aube TI034 programmable light switch that I want to replace with an Aube TI035 programmable light switch.

The info for the 034 is here:

and for the 035, here:

The reason I want to replace the 034 with the 035 is that the 035 can handle up to 2400 watts, whereas the 034 can only handle up to 500 watts.

According to the manual, the 034 goes in just like a regular light switch. I've had it in there for a couple of years and it works perfectly.

I bought an 035 and the electrician I called to install it said that he couldn't because, unlike the 034, the 035 required a "neutral" in addition to the line and the load wires. This is an old house and there is no neutral in that j-box.

On the web page above, it says that the connection required 3 wires (line, load, neutral). But the installation manual (pdf file available on that same web page), has an installation diagram showing only 2 wires: black (line) and white (neutral).

I am confused. Isn't "neutral" the same as "line"? I thought that "load" is the hot wire, "line" is the return (or neutral) wire, and 'ground" goes to ground.

Can anyone tell me if I can install an 035 where I only have 2 wires?

Thanks

[FDR]

On the 034, the switch draws it's operating power through the light in series with the neutral. Notic e that the instructions say that if the display is blank to make sure the bulb works?

On the 035 the switch has it's power come directly from the neutral. Mayeb this was done to reduce the hassle of losing operation when the load is disconnected. Or perhaps it's because this unit can be used to operate motor type loads.

Looks like you are stuck.

[David Martel]

Lurf,

So, why couldn't your electrician do this? You have a "line" wire bringing the electricity to the switch. You have the load wire traveling from the switch to the lights. You have a neutral returning the electricity from the light to the ground rod. The ground wire is a second wire connecting to the ground rod for safety reasons. If you need a neutral (and a ground) at the switch box and lamp box the electrician can pull new wire. So, why won't he?

Dave M.

[Pat]

Electricity is dangerous, so if you don't understand the circuitry, don't do it yourself! What you want to do is probably best left to an electrician.

You have a 2 wire system. Line and load. Line is the "hot" wire. Load is the "neutral" or "ground". The terminology here can be vague, so be careful: there is a difference between grounding and grounded. What you have here would normally be a white wire in modern wiring. What you are missing is the bare wire, or "copper" wire. The missing wire is also why you have 2-prong plugs instead of 3 prong plugs for your electrical outlets.

I like the older terminology better. You have a hot wire and a "working ground". You are missing the "mechanical ground".

If you are heart-set on that switch, you could have an electrician wire a mechanical ground for you and install the switch. But your load is pretty big so it would be much better to have the electrician rewire the whole circuit. In fact, that switch should probably be on its own breaker.

Good luck with it.

[PipeDown]

They probably changed it because they had too many returns or support calls due to just a blown bulb.

It also makes the switch compatible with fluorescent lighting (actually the real reason to change) particularly CFC bulbs.

[Pop]

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.

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.

HTH, Pop

[mm]

Did you do this on the phone. Congratualations to both of you, for being prepared and not wasting the other's time. And to him for knowing the merchandise that he doesn't even sell probably.

Even if he had to come out, congratulations to him and maybe you for reading the instructions and looking at the situation before starting.

That's probably because they didn't bother to update the diagram. Genereally, the text overrides a diagram (that is, it's more accurate), but also more complicated often overrides less complicated. In this case, the text is both. I'm talking about in practice. Of course they are supposed to have both the text and the diagram right, but often they aren't.

The load is the light bulb or whatever. It will be easier if you think of the line or the hot wire as the wagon, and the load as the potatoes in the wagon.

The line is both the hot and the neutral, but if I'm wrong or sometimes they use it differently, it's the hot.

Bingo.

Do you have BX or Romex? Metal shielded cable or plastic.

[Kevin Ricks]

So why would it not be compatable with CFC bulbs already? I have a fixture fed by neon lit 3 way switches which work fine with a CFC bulbs. The lighted switches get the neutral by the same principal- through the unlit bulb. Kevin

[Bud--]

The switch box might contain only a hot and switched-hot with no neutral (presumably the case here). Hopefully the electrician looked at the box and determined this (did not make a diagnosis over the phone). If wired with cable (Romex, BX) you can't just pull a new wire, and fishing may be a lot of work/cost.

I hope the post by Pat was meant to be a joke. Pop's description of terms is good but I would add that in addition to "earthing" the "ground" wire also provides a low resistance path back to the source to trip the circuit breaker if a "hot" connects to a grounded device or box.

bud--

[LurfysMa]

I think this is correct. The electrician was more than happy to pull a neutral wire. He just warned me that it would be expensive.

[LurfysMa]

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.

1. 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?

I don't plan to do this myself. I just wanted to understand it.

Thanks for the help.

[Pop]

Sounds like you have a pretty good handle on it.

Pop

[Kevin Ricks]

Some programmable switches/Timers have a battery to keep the clock and don't need a dedicated neutral.

Kevin

[LurfysMa]

Thanks for the help.

[LurfysMa]

Thanks for that link. I had Intermatic timers some time ago, but (a) they did not have the sunset/sunrise feature and (b) they tended to fail too often.