ZOOZ Dimmer

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Dennis Alwon

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Is this think compliant? I think not

enhance
 

Dennis Alwon

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What I see here is line and load on the zen dimmer with a constant neutral and then a neutral switched from the other 3 way-- that 3 way only has 2 terminals connected. Technically we are switching the neutral but there is always a neutral unswitched at the light.

I am not sure how the standard 3 way is actually controlling the load on the Zen dimmer.
 

hbiss

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Usually dimmers like that use the hot to do that, not the neutral. Can't think of a 3-way setup that wouldn't have a 3 wire cable to the switch locations. Why use the neutral?

-Hal
 

Adamjamma

Senior Member
that switch setup is using the three way system to switch the neutral power not the hot... but the dimmer itself is the only part of the circuit carrying the hot as well. Not too sure about that. Normally, isn't it the hot that gets switched and neutral is run short?
 

jumper

Senior Member
that switch setup is using the three way system to switch the neutral power not the hot... but the dimmer itself is the only part of the circuit carrying the hot as well. Not too sure about that. Normally, isn't it the hot that gets switched and neutral is run short?

Yes, except for a few specific applications the neutral is never switched and when it is, it is concurrent with the hot conductor.
 

Adamjamma

Senior Member
404.2 Switch Connections. (A) Three-Way and Four-Way Switches. Three-way and fourway switches shall be wired so that all switching is done only in the ungrounded circuit conductor. Where in metal raceways or metal-armored cables, wiring between switches and outlets shall be in accordance with 300.20(A). Exception: Switch loops shall not require a grounded conductor. (B) Grounded Conductors. Switches or circuit breakers shall not disconnect the grounded conductor of a circuit. Exception: A switch or circuit breaker shall be permitted to disconnect a grounded circuit conductor where all circuit conductors are disconnected simultaneously, or where the device is arranged so that the grounded conductor cannot be disconnected until all the ungrounded conductors of the circuit have been disconnected.

thus it violates code, at least how I read it, unless I have not read the section correctly.
 

jumper

Senior Member
404.2 Switch Connections. (A) Three-Way and Four-Way Switches. Three-way and fourway switches shall be wired so that all switching is done only in the ungrounded circuit conductor. Where in metal raceways or metal-armored cables, wiring between switches and outlets shall be in accordance with 300.20(A). Exception: Switch loops shall not require a grounded conductor. (B) Grounded Conductors. Switches or circuit breakers shall not disconnect the grounded conductor of a circuit. Exception: A switch or circuit breaker shall be permitted to disconnect a grounded circuit conductor where all circuit conductors are disconnected simultaneously, or where the device is arranged so that the grounded conductor cannot be disconnected until all the ungrounded conductors of the circuit have been disconnected.

thus it violates code, at least how I read it, unless I have not read the section correctly.

You are correct and that is the appropriate code reference. Good job!
 

Dennis Alwon

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The purpose of not switching the neutral is to ensure the neutral is not disconnected at the load when the ungrounded conductor is energized. This is not the case.

Even more so how is this even working-- you already have a neutral at the light and at the dimmer then you switch another neutral to the dimmer. :?
 

wwhitney

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The neutral to the load is not being switched, so I don't see a violation. The ZOOZ Dimmer is making or breaking the ungrounded conductor to control the load, as it should. The other 3-way (or 2-way) switch isn't part of the circuit, it is just a control input to the ZOOZ dimmer.

Cheers, Wayne
 

don_resqcapt19

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I don't think you are actually switching the neutral. You are driving the voltage on the red wire to zero as part of the internal electronic logic in the dimmer switch. I assume the internal logic drives some type of electronic latching relay, and every time the voltage status of the red wire terminal changes the latching relay changes state. That permits the 3 way dimmer to be used with a standard switch at the other location.
 

Dennis Alwon

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I agree the neutral is not switched to the load but it is being switched -- the common on the standard 3- way is a neutral and switches the red wire but is that not a neutral?
 

Adamjamma

Senior Member
I don't think you are actually switching the neutral. You are driving the voltage on the red wire to zero as part of the internal electronic logic in the dimmer switch. I assume the internal logic drives some type of electronic latching relay, and every time the voltage status of the red wire terminal changes the latching relay changes state. That permits the 3 way dimmer to be used with a standard switch at the other location.

If it is simply completing a loop then why is the neutral bonded? In a fault in the bulb or in the lighting circuit from another bulb you now would have fault current running through the switches.

better design would be to have the current run through the switches before coming to the dimmer, so the load side of first switch- the common- becomes the feed to the dimmer. But, perhaps this meets the exception for a loop, except I thought the loop was supposed to be kept from any fault conditions by ensuring the live to be disconnected before or at the same time as the neutral.
 

al hildenbrand

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Minnesota
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I don't think you are actually switching the neutral. You are driving the voltage on the red wire to zero as part of the internal electronic logic in the dimmer switch. I assume the internal logic drives some type of electronic latching relay, and every time the voltage status of the red wire terminal changes the latching relay changes state. That permits the 3 way dimmer to be used with a standard switch at the other location.

What I see here is line and load on the zen dimmer with a constant neutral and then a neutral switched from the other 3 way-- that 3 way only has 2 terminals connected. Technically we are switching the neutral but there is always a neutral unswitched at the light.

I am not sure how the standard 3 way is actually controlling the load on the Zen dimmer.

Dennis, I agree with Don. I look at your diagram and I see the "signal wires" that Panasonic Whisper Green exhaust fans use to control their plug n'play relays that change exhaust speed. Panasonic has two red wires, one of which is solidly connected to the neutral, the other of which is considered to be line voltage. . . except it is only an electronic circuit level line voltage that is shunted to the neutral through a standard snap switch, basically taking the logic state from signal voltage while open to zero volts. The circuitry uses the logic state change however it is engineered to.

The ZOOZ diagram, while labeled as it is, only shows a single traveler. One cannot wire a threeway that is described in 404.2 with a single traveler. . . therefore, what is shown in the ZOOZ diagram is not a Code violation.

I'll bet that the manufacturers of this are going to get push back from various members of the AHJ community until the language of the documentation becomes clearer.
 

Little Bill

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The way I see it, the neutral is not being switched. The Dimmer uses the neutral in it's circuit. It's always present at the dimmer, and depending on the dimmer's switch position, it's either fed straight up from the direct connection or through the other 3-way (or SP switch if you choose). The 3-way is only for on/off. The reason for the 3-way is only that it is already present. You could change it to a SP switch. That's similar to how a Lutron Casetta or RF switch works in a 3-way setting. Only difference is that Lutron says to jump one of the travelers to the common on the standard 3-way.

I don't know the Z dimmer but I bet it can be a stand alone and would require a neutral in the box. It would just be used from one location.
 

Adamjamma

Senior Member
Well, I guess it is one of the reasons why we are being told to provide a neutral in the boxes but... I would not actually bond the neutral to switch and dimmer and light... however, I can see it doing something similar to my meter when I am testing continuity... if it sees a continuous signal then it allows power through a relay, but if signal is interrupted then it shuts off power...

This then would meet the exception clause of using a signal loop rather than switching the grounded conductor... which was clause C I think...

Anyway, After sleeping on it, I reverse my position on it being illegal provided it is using the three way/four way circuit as a continuity style meter circuit rather than switching power... but would have to see more on it to be sure.
 

RAKocher

Senior Member
Location
SE Pennsylvania
I can imagine the ZOOZ dimmer using the common and just one of the travelers any number of existing 4w's & 3/w as an external s/p switch to an internal double throw relay.
Than the ZOOZ would always know what on/off state it's currently in and when it's requested to toggle its on/off state.

But it could do that without externally connecting the lighting circuit's neutral to the existing switches.
They're probably just saving themselves a 5th terminal on the ZOOZ and figure it's just neutral... no harm done!
 
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drcampbell

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The Motor City, Michigan USA
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How about putting a voltmeter on it and letting us know whether they're switching 120 volts or a logic-level low-voltage circuit?
If it is a logic-level circuit -- and especially if it's a current limited source that can only push a few mA -- I can't see the harm.
 
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