Simply Automated Switches & Sharing Neutrals

[DIYHO]

When you say "no current detected on the neutral", how did you test for that? You need to use a multimeter with a clamp to test for current. Putting a multimeter to it looking for voltage will read zero even if it is carrying voltage and possibly current because the other leg of the multimeter will be on a wire that is common to that neutral.

I didn't test for "current" in the true sense (i.e multi-meter or inductive clamp), but rather using a no contact voltage sensor. I do have an inductive clamp that I could use to easily test for current if I actually need a value. What I did instead was put a load on each circuit and used the no contact voltage sensor to test for a voltage "current"

Would it be a huge deal to properly wire those switches.
I would feel better for you. Is there unfinished attic or basement above/below the walls with those gangs? Even if you have to tear out a little drywall here or there, patching is not that hard.

In all honesty .... yes. Most of the wiring is now buried inside of 12" or more of foam insulation in some places, and pretty much all the walls that contain the problem boxes are also foamed. I wish it was as simple as just cutting out a little dry wall, but it's not. I would have to cut out a lot of brand new dry wall (dens armor plus), rip out my foam insulation, then repair everything. We are probably talking easily $3000-5000+ just to get the boxes properly wiring for UPB 3-way switching and to fix some of the other problems with wiring I have found (4 function bath fan with wiring for only 2 functions), not to mention a mess of my personal time to do the things that aren't contracted out.

If the simply automated switches work like Insteon, you can bring in a hot/common/ground and run the swich off a completely different circuit.

I'm not familiar with how Insteon works, but it sounds like a virtual switch. You can set up a virtual switch using a US2-40, like the left switch in my picture. This switch does not control a load and is not wiring in any way to the master switch that does control the load. It however can be programmed to control any UPB controlled load in the house, so it could be setup as a virtual 3-way switch, however I am uncertain if LED status will work.

I thought it was code that common's follow along everywhere. I just built a house and made no special requests and every single box that I have opened (and I have opened a lot of them) has a common regardless of whether it is the primary or slave box on a multiway switch setup.

The problem isn't the lack of a common, but rather having an available common on the same circuit.

 

[Digger]

I think Virtual Switches as Lou suggests is your best bet (a few more bucks for the switches but not a lot and a hell of a lot easier then rewiring if your walls are closed). Your concern about the LED status is a valid one as they are not always in sync (at least the way I have mine set up they are not).

There are some controllers coming out that may address this. I dont have the Web Mountain controller but maybe someone else does. I am waiting for the ISY for UPB and if it is released this week or next for Beta I will try that and I believe that it will track the LED's etc. If the ISY is not out in the next two weeks for Beta I will go with the Web Mountain because I need something for the holiday lighting etc.

 

[DIYHO]

I sent a tech support request to Simply Automated this morning after posting my test results and requested they have a tech check out this thread and provide input/clarification. I am pleased to say they responded promptly, so hats off to Simply Automated for the quick response.

What follows is the response.

DIYHP,

The responders to your question are correct for what they are talking about.
What they, and the NEC, are talking about is multiple loads on a shared
neutral.

There was also a comment about grabbing a neutral that is a return for a 220
load. Though the comment is correct it does not mean that there is a
separate neutral buss for each phase. All neutrals are tied to a common buss
at the breaker panel and that buss is connected to earth ground. What the
comment refers to is a situation where the neutral becomes disconnected from
the breaker panel and uses any return path it can find.

That being said, Your US2-40 and USR are a completely different situation.
The USR Does not pull load current from the neutral. It is an extension of
the switch logic inside the US2-40. This switch is specifically designed to
be used as a 3 way with our devices. It is UL and CSA approved and is not a
"load" circuit.


You may post this response to coccoontech if you would like.


Feel free to call the below number with any questions or technical
assistance about Simply Automated products.



Ken Boehme
Tech Support
Simply Automated Inc.
6108 Avenida Encinas suite B
Carlsbad, CA 92011-1044
1-800-630-9234 X152​

My response asking to verify I was reading what he said correctly, and he confirmed I was.

Thanks for your reply.

This is what I suspected was the case, but just so I have it clear.
Tying in the neutral lead from the USR into a separate circuit does not lead to a shared neutral scenario I was initially concerned with and therefore is neither a code violation or a safety hazard.

DIYHP ​

Thanks again to Ken at Simply Automated for the prompt reply and clearing up the confusion.

-----------------

While I have everyone's attention, does anyone know how dimming modules and/or switches handle low voltage power feed (i.e. module/switch downstream of transformer)?

And finally, another wiring question .... how does one go about wiring a US2-40 as a hardwired 3-way remote switch or is the only way through a virtual link?

 

[apostolakisl]

I think I know what is going on after reading your comments and looking a little at UPB three ways and what Digger said. Insteon doesn't have a three way type switch (as far as I know) but rather you link two independent switches to behave the same as a three way.

With Insteon, the led's track the status just fine. UPB has a little different led scheme, but it seems like you could buy two of the regular UPB switches and link them together and have the led's work. Each switch would then be electrically independent so two different commons is not a problem. It looks like it will cost about $30 extra to do it that way but requires no mind wrenching thought process to ensure the electrical is safe and passes inspection (and no pulling out drywall).

I actually have extra wires going between switches since replacing regular 4 ways with Insteon. The three ways used all of the wires because I needed to convert the traveler to an always hot wire to run the switches internal draw.

 

[Digger]

DIYHP I reccomend that you check with your local code authority to see if they approve what SA is saying. In the end they have final say.

Personally I would not share the neutral but perhaps I am misinterpreting the NEC for Multiwire Branch Circuits in dwelling units. Keep in mind that a GFCI can be affected by any imbalance on one or both of the circuits.

 

[IndyMike]

Hello again DIYHP,

I'm glad that you went the extra mile to contact SA technical support. I'm not sure that I agree with everything, but I will concede that the switch may be designed to share a neutral connection. Getting your inspector to agree with this may be another matter.

I copied the basic diagram from the SA installation sheet below:

The following is what I believe you have based on your description of the "re-tasked neutral":

I would encourage you to develop a similar schematic for your inspector should the need arise. I'm a little astonished at the number of connections these switches have. The basic configuration is not dissimilar from my old Leviton HCM06 (X10) units. The difference is 2 extra connections on the master switch and 3 additional on the slave. That's a lot of additional connections (space in your J box) to power 2 LEDS.

The J box photo that you posted looked extremely crowded. You've got a lot of wire nuts to cram back into that box. I noticed that the US2 dimmers were available in "multi-rocker" configurations. If the second (third and fourth) rockers can be setup in a virtual configuration (communicating over the powerline), you could eliminate some slave switches and free up some Jbox space at the same time. Not sure if this is possible - I'm not at all well versed on the UPB line.

 

[DIYHO]

DIYHP I reccomend that you check with your local code authority to see if they approve what SA is saying. In the end they have final say.

Personally I would not share the neutral but perhaps I am misinterpreting the NEC for Multiwire Branch Circuits in dwelling units. Keep in mind that a GFCI can be affected by any imbalance on one or both of the circuits.

You are correct, the inspector has final say. The problem I have been having from the beginning is the situation isn't really a "shared" neutral as the NEC defines it, since both circuits still have their own neutral.

 

[DIYHO]

I'm glad that you went the extra mile to contact SA technical support. I'm not sure that I agree with everything, but I will concede that the switch may be designed to share a neutral connection. Getting your inspector to agree with this may be another matter.

I copied the basic diagram from the SA installation sheet below:

The following is what I believe you have based on your description of the "re-tasked neutral":

Yes, that looks to be right with the exception that the hot at the USR-40A doesn't continue on. The re-tasked hot white traveler is a dedicated feed for the USR-40A now. I moved the left US2-40 hot feed to the other circuit, even though it wasn't pulling any load either. I had originally set it up as in the picture in order to keep all the lighting control on lighting circuits, but decided to bail on that in lieu of the wiring it to a proper hot. I'm about to head over there to continue working on getting the final wiring done, so I will rewire the box, put in a GFCI and see what happens.

The J box photo that you posted looked extremely crowded. You've got a lot of wire nuts to cram back into that box. I noticed that the US2 dimmers were available in "multi-rocker" configurations. If the second (third and fourth) rockers can be setup in a virtual configuration (communicating over the powerline), you could eliminate some slave switches and free up some Jbox space at the same time. Not sure if this is possible - I'm not at all well versed on the UPB line.

It is pretty crowded, but believe it or not, it all fits, and the pictured box better boxes in terms of what needs to fit in there. If I hadn't put in the super blues, I would be screwed right about now.

 

[IndyMike]

I'm about to head over there to continue working on getting the final wiring done, so I will rewire the box, put in a GFCI and see what happens.

Put in a GFCI?? On a wall switch? I thought these switches were controlling overhead lamps. Is the GFCI going in the panel (feeding the switches) or is it an outlet (controlled by the switches)? Either way, I don't understand the installation.

 

[Digger]

I'm about to head over there to continue working on getting the final wiring done, so I will rewire the box, put in a GFCI and see what happens.

Put in a GFCI?? On a wall switch? I thought these switches were controlling overhead lamps. Is the GFCI going in the panel (feeding the switches) or is it an outlet (controlled by the switches)? Either way, I don't understand the installation.

If the switches are sharing a neutral (I dont think so anymore after your drawings) and were slaves of a GFCI breaker or outlet it would trip the GFCI.

 

[IndyMike]

Just thinking about this.

Why would a double pole breaker protect you from exposing things to 240 sharing a common with 2 different phase 120 hots in the event that the common is interupted? (that was a tough sentence)

The breaker only pops if current limits are exceeded, but that may not happen. If the resistance to flow on the one leg is equall to the other leg, both sides will still be "seeing" 120 since this wiring error would effectively be putting the two legs in series on a 240 circuit.

I would think you would want a GFCI circuit since it pops when the current fails to return on the common.

Hello Lou,

I was searching for the reference to the GFCI breaker and saw your question -

A double pole breaker would not help in this instance. If a single load was enabled on one phase, and the neutral interrupted, the neutral would be pulled and the opposite side devices exposed to 240V (320 V-Peak).

This was a mixed reference on my part (I apologize). I had an issue with the fact that the "old" NEC code allowed the 2 phases of a shared common circuit to be powered off separate, single pole breakers. Shutting off one breaker would leave the opposite phase energized with current on the neutral. Your typical home owner isn't accustomed to dealing with either of these conditions. I'm happy to see that the 2008 code has corrected this.

As far as the GFCI breaker is concerned, it would provide a belt an suspenders level of protection. In the end DIYHP either needs to trust the SA assertion that the switch is isolated from the neutral, or seek another configuration.

 

[apostolakisl]

Just thinking about this.

Why would a double pole breaker protect you from exposing things to 240 sharing a common with 2 different phase 120 hots in the event that the common is interupted? (that was a tough sentence)

The breaker only pops if current limits are exceeded, but that may not happen. If the resistance to flow on the one leg is equall to the other leg, both sides will still be "seeing" 120 since this wiring error would effectively be putting the two legs in series on a 240 circuit.

I would think you would want a GFCI circuit since it pops when the current fails to return on the common.

Hello Lou,

I was searching for the reference to the GFCI breaker and saw your question -

A double pole breaker would not help in this instance. If a single load was enabled on one phase, and the neutral interrupted, the neutral would be pulled and the opposite side devices exposed to 240V (320 V-Peak).

This was a mixed reference on my part (I apologize). I had an issue with the fact that the "old" NEC code allowed the 2 phases of a shared common circuit to be powered off separate, single pole breakers. Shutting off one breaker would leave the opposite phase energized with current on the neutral. Your typical home owner isn't accustomed to dealing with either of these conditions. I'm happy to see that the 2008 code has corrected this.

As far as the GFCI breaker is concerned, it would provide a belt an suspenders level of protection. In the end DIYHP either needs to trust the SA assertion that the switch is isolated from the neutral, or seek another configuration.

Man, those wiring diagrams for the UPB 3 way deal are a bear. The UPB people love their switches, and they do have a point about being more noise resistant than Insteon, but Insteon is a lot simpler on the wiring diagram end of things.

I could be wrong on this, but it seems like the only thing that common serves is to close a circuit that powers the led's on the switch. Perhaps the fact the we are only looking at milliamps of current lets you get away with this scheme. Also, if the only thing powered is led's then you are looking at a situation where diodes in the device only allow current to flow one way which would prevent a 240 situation if the common turned hot 120.

 

[DIYHO]

I'm about to head over there to continue working on getting the final wiring done, so I will rewire the box, put in a GFCI and see what happens.

Put in a GFCI?? On a wall switch? I thought these switches were controlling overhead lamps. Is the GFCI going in the panel (feeding the switches) or is it an outlet (controlled by the switches)? Either way, I don't understand the installation.

There is one receptacle on the lighting circuit that needs a GFCI. I did testing last night with the GFCI in place and it did not trip.

 

[Digger]

I'm about to head over there to continue working on getting the final wiring done, so I will rewire the box, put in a GFCI and see what happens.

Put in a GFCI?? On a wall switch? I thought these switches were controlling overhead lamps. Is the GFCI going in the panel (feeding the switches) or is it an outlet (controlled by the switches)? Either way, I don't understand the installation.

There is one receptacle on the lighting circuit that needs a GFCI. I did testing last night with the GFCI in place and it did not trip.

Then in my opinion (not stating a fact) you are not sharing a neutral or there is no load at all from the slave switch (or it is below the trip current of the GFCI.

Good Luck with the inspection!

 

[apostolakisl]

I'm about to head over there to continue working on getting the final wiring done, so I will rewire the box, put in a GFCI and see what happens.

Put in a GFCI?? On a wall switch? I thought these switches were controlling overhead lamps. Is the GFCI going in the panel (feeding the switches) or is it an outlet (controlled by the switches)? Either way, I don't understand the installation.

There is one receptacle on the lighting circuit that needs a GFCI. I did testing last night with the GFCI in place and it did not trip.

Then in my opinion (not stating a fact) you are not sharing a neutral or there is no load at all from the slave switch (or it is below the trip current of the GFCI.

Good Luck with the inspection!

I agree. By definition a GFCI trips if the common isn't carrying the same current as the hot side. So, if you are using a common that follows a different path (not back through the same gfci that carries the hot), then it will trip. A GFCI must have a minimum amount of current to trip and perhaps the milliamp draw of leds isn't over that limit.