Switch has power, but lights don't come on


(Dave) #1

I have a GE/Jasco switch that is hooked up, has power (LED is on), added to the network, and responds to the mobile app. But it doesn’t actually turn on the lamp it’s connected to when operated manually. The only thing operating the switch or the app does is cause the LED to go on or off, and clicking the relay. Here’s what the wiring looks like (and those are the only two wires in the box).

Any suggestions?


(Ajf) #2

Wiring Diagram

This is what you have, there’s no neutral there so I don’t think you can use that switch.


(Dave) #3

I thought so. Any suggestions on a thing I can use to control this lamp?


(Ajf) #4

Switches only go on the hot wire. Since the power goes to the fixture first, there’s no neutral at the switch box. If power went to the switch box first, then the neutral would be there. Like this diagram:Wiring Diagram 2


(Ajf) #5

Not sure what you can use since I think there always needs to be a neutral .


(Dave) #6

I wonder if this will work, if I put it up at the ceiling fixture box?


(Andrew Urman) #7

@chzdanish you could use the GE Z-Wave In-Wall dimmer. No neutral required, just line and load.


(Dave) #8

Ah, excellent. Thanks.


(Ajf) #9

Cool, always heard that neutral must be present for just about all HA switches.


(Chrisb) #10

Yeah, what Andrew said. I’ve got a couple of the dimmers and they work well enough. The one thing is they don’t work with CFLs. Also if you don’t have enough load on the LED lights they might be on at a really dim level, but this is only a problem is you have a very light load.


(Pete Molina) #11

@chrisb

Can you explain this statement in a little more detail?

Also if you don’t have enough load on the LED lights they might be on at a really dim level, but this is only a problem is you have a very light load.

I have a number of switches that don’t have a neutral and would like to use something like the linked switch, but don’t understand the issue(s) of using LED bulbs. I’m fine not being able to use CFL’s.


(James Van Booven) #12

Pete,

Traditional old toggle switches allow current to flow in the from the hot wire (one of the black wires) through the switch, and out the load side (the other black wire) from the switch to the light.  Current flows through the switch when the switch is on, meaning that the circuit is closed/complete.  When the switch is off, the circuit is open, and current can’t flow through the switch.

Z-wave switches require power to flow through them all the time (this is how they have power to light up their status LED, and listen for z-wave commands), even when the light is off.  For the switch to have power means that the power has to flow through a completed circuit.  There’s two ways to accomplish the switch having power…

Most z-wave switches require a neutral (white wire).  On these, there are two paths of current flowing through the switch.  The flow of current for the light comes in through the hot black wire to the switch, and out the load wire (often – but not always – black) to the light.  The flow of current for the switch comes in through the hot black wire to the switch, then out the neutral white wire.  This allows current to flow through the switch and power it even when the light is off.

The other way that a few z-wave switches can get their power, which does not require a neutral, is to let a little bit of power trickle through the switch to the light.  This means the light always has power (a lot when the light is on, just a trickle when the light is off).  This is OK with incandescent bulbs which have high resistance and won’t light up with just a little bit of current.  However, with energy-efficient lights like LEDs, this flow of current is enough to make them light up, pulse, flicker, pop on and off, etc., even when they are supposed to be “off”.  Lights are not intended to be powered when off, but since smart switches have to be powered, this trickle current for the lights is one way to let the switch have power.


(Chrisb) #13

@ppmo,

Exactly what James said in that last paragraph. The switch without a neutral is letting a small amount of power thru. I have this hooked up to me dinning room light, which has three incandescent bulbs in it. At 75 watts each this amounts to 225 watts to have them on full bright. That’s quite a bit and a little trickle of power isn’t going to do anything to make them light up.

But imagine replacing these with LED lights, for example. A 15 Watt LED is similar to a 75 Watt incandescent So if I replace all three 75 with 15 LED bulbs, now my load is only 45 watts for the whole light… only 1/5 of the load we previously had. Now that small trickle make be enough to light up those LEDs a little.


(Pete Molina) #14

Thanks to you both, I believe I understand it better. One more question (to check my understanding). In another thread, I saw a reference to this GE Switch, which I saw does not need a neutral, but works with incandescent or dimmable LEDs. I assume based on my newly learned info that this is because a dimmable LED has enough resistance prior to turning on that the trickle current doesn’t activate it. Does that sound right?


(Jim L) #15

First post here. But take a look at the Evolve Dimmer. http://www.amazon.com/gp/product/B006U1TR9I/ref=oh_details_o02_s00_i00?ie=UTF8&psc=1
According to the reviews this will work great with LEDs. I have two arriving today.


(Pete Molina) #16

@JimL I’ve got two of these waiting to be installed, but they require a neutral wire at the lightswitch.


(Boris M) #17

This one does not rwquire a neutral.