I have a programmable switch that requires a neutral line to work. The switch boxes in this old house do not have a neutral line. I was told this by an electrician.
However, my son has a newer house, which may have a neutral line. I have an old Wiggy voltage tester. How can I test for a neutral line? How can I tell the identify the line, the load, and the neutral (if there is one)? I believe the ground will always be a bare wire, right?
Thanks
Look for a white wire that is not connected to a switch. There usually will not be one unless the power is being fed through that box and then there will be 2 or more white wires connected together.
Also there is no voltage present between ground and neutral. If there is no ground, then use mechanical timer(the wind-up type) I intentionally installed both types for our bathroom to see which one last longer.
The voltage between line and load would be the same as between line and neutral, right?
What about between load and neutral? I would think that would also be 0 volts. Right?
I don't understand what you mean about the timer.
*The ground can also be green.
The voltage between line and load would be the same as between line and neutral, right?
*Wrong. The resistance in the load could affect the voltage reading. On a Wiggy it may show up as just the little light coming on, but not the solenoid kicking in. *Yes if there is no power on the load.If there is only one two wire cable with ground going into the switch box, the white wire is likely to be the line and the black would be the load. If you have more than one cable in the box with the white wires spliced together, then you are most likely to have a neutral.
I'm trying to understand - you're saying that the hot wire was run to the switch, but not the neutral? So the switch box only has one wire in it? Why would anyone do that?
Most hot wires in a switch box should be black (with some exceptions); neutrals always white, and the ground either bare or green.
Could easily be a "switch leg" where the feed cable goes directly to the switch box and then a 2 wire plus ground cable is dropped to the switch box. The white in the switch leg should be marked with black or red tape to indicate that it is not being used as a neutral. Perfectly code compliant up until the latest revision.
To provide a neutral in this situation the switch leg would have to be repulled with 3 wire plus ground cable. Also boxes should be re-evaluated for box fill, one or both may need to be replaced with deep boxes.
nate
If the power switch is off. If it's on, the voltage would be 117 or so on a regular lightbulb/fan etc. circuit.
Make a drawing of all this and stare at for 5 or 10 minutes total. Use the same technique for more complicated situations as you progress. For my Toyota car, I've been staring at the manual for about 20 hours so far, and I think I understand about all that I can. If it were an American car, there woudl be more info and a better manual and 10 hours might be enough.
Neither did I.
I think Tony made a couple assumptions, but they make sense to me...
the one place in a house that I've used or wanted to use a "programmable switch" was for the bathroom vent fan, to get all the steamy air out after a hot shower, but e.g. with a regular switch you either turn it off when you leave for work or else leave the fan running all day. What you really want in that situation is a timer, where it will run for say two hours after you turn it on then shut off.
*IF* that is the OP's situation, a spring timer is a perfectly good solution and easier than repulling wire to use her device of choice. If it's something else, probably not so much.nate
All you have to do is look in the junction box.
There should be one green or bare wire going from the junction box to the metal mounting tab of your switch. That is the /ground/ and though it is not energized /cannot/ be used as neutral.
Next, there will be one wire going to each terminal of the switch.
If there is a white wire in the junction box that is taped off...or perhaps runs to some other circuit...then that is your neutral wire. If there are no other wires in the box (or wires that are anything other than white) then there is /no/ neutral.
NOTE: If one of the wires connected to the switch is white...it is /not/ a neutral but simply the wire going to the bulb. It may have a piece of tape on it with a color other than white.
Noi, the switch would have both a hot wire and the wire going to the light/load connected to it. The neutral would never be connected to the switch. Most times, around here at least, the way the wiring is run, the box has a neutral in it anyway. But until very recently, there was no code reqt to have a neutral in the switch location.
Um, sort of correct. The voltage between line and load would only show a voltage drop. The actual voltage present would not be measured. The voltage drop reading should be very miniscule. If not, serious issues are at hand.
The difference between load side of line and neutral *might* be different than between line and neutral at service entry. Voltage drop and conductor/termination resistance comes into play with this. I don't recall the allowable percentage, but somewhere along 5-10% max of premise voltage for circuit, or nominal voltage rating of device being powered. Most devices have an acceptable voltage range. However, anything approaching this in a residential setting is cause for concern due to short runs not providing enough conductor resistance, therefore leading one to suspect improper/corroded terminations in the circuit.
This is a generalization, of course.
Lazy electricians and cost cutting measures. The difference between sourcing or sinking a load. These can confuse a novice. Proper application would be that the neutral should pass through the j-box the switch is located in with the hot being switched before continuing on to the switched device. Preferable should be a more "proper" term, I suppose.
Usually the black tape on white wire is to denote a switched hot that is used in the feed of a 3-way were both conductors in the romex are hots. For a normal switch this is not necessary.
I realize this is not a perfect world and many will cut whatever corner that is allowed to facilitate a "legal" installation however funky this may be. Most times the dollar wins out over intuitive installation. People forget that what the code states is "what is allowed", not what is preferred or is better.
Many only care about the "it passed" nature of the trade, not the quality and down the road maintenance of the installation.
Why exactly are switch legs un-preferable?
Chip C Toronto
A lot of line-powered switches require it.
For example, my Insteon switch modules require a tiny amount of power to listen for remote commands.
Occupancy switches - turn a light on when someone enters, and turns the light off after you leave - requires a neutral on some, a ground on others.
What's the difference between a "voltage drop" and "actual voltage present"? I think you may be assuming he's talking about measuring the voltage with the load connected to the line? I don't think that's the case. I took it to mean that the load is disconnected from the line and the meter is hooked between line and load. That is what you could do at a switch box going to a load.
The voltage
If you hook a voltmeter between the line and load and that is the only path for current to the load, then you have a voltage divider between the meter and the load. How much voltage you see is going to depend on the resistance/impedance of the meter compared to the load. With any reasonable load, most of the voltage is going to be across the meter, because it's resistance is huge compared to the load. If you had a 100W light bulb as the load, and an electronic VOM, you'd see almost all the 120V across the meter.
If not, serious issues are at hand.
You might be right. I presumed that the load was in circuit. The drop between line and load should be barely observable, if at all. The drop across the load accounts for the wiring and the load. This is still small.
It indicates it is a "live" conductor - not a neutral as white would indicate.
Jennifer-
The wire coming from your fuse/breaker box to the switch box is the "Line". The wire that goes from the switch box to what is being switched, is the "Load" wire.
Now go to the load being switched. One wire is the "Load" wire from the switch. The other wire is the Neutral line you need.
I think your best alternative would be to re-route the existing Neutral line through the switch box. Otherwise you may need to run a new Neutral wire from the fuse/breaker box to the programmable switch, and on to the load.
Perhaps your electrician can advise you.
Fred
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