Simply Automated Switches & Sharing Neutrals

[DIYHO]

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.

Per my initial testing (results posted in a previous post), turning one or the other circuit off while leaving the other on did not energize any of the involved neutrals regardless of what state the switch was in (powering the light, or not).

TAs 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.

The GFCI is (more or less) at the end of the circuit with nothing on the load side, while this switch box (and most all of the others where this switch/neutral situation occurs) is essentially at the head of the circuit if not the first jbox in the circuit.

In this particular circuit the USR-40A switches neutral is tied into what was initially intended as a dedicated circuit for low voltage purposes, but had to be abandon because I needed the circuit for the living room receptacles due to the electricians screw up. Luckily I had two dedicated circuits for low voltage, so hopefully I will only need one of them. Long story short, I do have a jbox right outside the sub-panel where I was planning on putting in a UPB relay to control on/off of the low voltage transformers. I could put in a GFCI in this jbox that would effectively provide GFCI protection for the entire circuit if you feel this would be a better location for a GFCI.

I was giving this wiring some more thought last night and realized that in this scenario, the actually neutrals from the two circuits are not physically tied together except at the sub-panel buss, as there is no neutral wire from the USR switch back to the other circuit. The only connection to the other circuit is through the hot feeds to the USR switch. Now I don't know if this makes a difference or not as this goes beyond my knowledge of circuits and I don't really have the time right now to research the principles of it all.

Would it help to pull out the multimeter to understand what is going on here with the switch and neutrals from the two circuits under various scenarios? This would certainly alleviate any concerned I have, and perhaps would be a sufficient demonstration for the inspector showing the setup isn't a code violation. If so, what do you feel would be the most appropriate measurement to take? Voltage and current on the switches neutral or voltage and current on the circuits neutrals?

Attached is updated pic of the box showing the other two switches (one with a single light on the load, the other with no load) now tied into the true hot from the sub-panel in the box. The arrows show the re-purposed hot white traveler (red arrow) from the other circuit now dedicated to the USR, and the USR switches neutral lead (green arrow) that ties into the neutral of the circuit that comes into this jbox.

 

[Sandpiper]

........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":

Thanks IndyMike. This schematic helps a lot for my understanding. But I must still disagree that this setup meets code.

Using the "re-tasked neutral" schematic, if you follow the current flow from hot, through the switch, through the load, to neutral, and to the panel neutral, it becomes apparant that the the feed is from one circuit, but the neutral is on the other. This is in effect, two circuits using the same neutral, or a shared neutral.

Follow the current flow, and see if you agree.

If the load was wired to the to the master switch, on the left where the hot originates, this could be wired to satisfy code.

 

[Sandpiper]

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

Another thing I just realized is that this diagram shows it is OK to connect the neutrals from two circuits together. Code does not allow this. Code enforcers would consider this to be parallel conductors. I think Simply Automated ought to check into this. The NEC allows parallel conductors but only under some prescribed conditions which are not met in this situation. With parallel conductors, there is no way to control how much current each of the individual conductors will carry, so therefore an overloaded conductor can result.

 

[DIYHO]

Here is a schematic of the setup that is accurate. The other one was close, but not quite.

 

[apostolakisl]

........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":

Thanks IndyMike. This schematic helps a lot for my understanding. But I must still disagree that this setup meets code.

Using the "re-tasked neutral" schematic, if you follow the current flow from hot, through the switch, through the load, to neutral, and to the panel neutral, it becomes apparant that the the feed is from one circuit, but the neutral is on the other. This is in effect, two circuits using the same neutral, or a shared neutral.

Follow the current flow, and see if you agree.

If the load was wired to the to the master switch, on the left where the hot originates, this could be wired to satisfy code.

This diagram is clearly taking the hot from one j box and using the neutral on the other jbox for the load, not just to power the leds on the switch. So if the hot/neutral on the second box are not on the same circuit as the first box, I don't see how this could be OK.

If you went to your panel and swapped your breakers around you could keep both hots on the same phase so the 240 thing could be avoided. But I don't know if that makes it OK for code.

I keep going back to putting two independent switches and linking them via UPB power line commands instead of hard wiring them together. There is no doubt that that is OK.

 

[mustangcoupe]

I keep going back to putting two independent switches and linking them via UPB power line commands instead of hard wiring them together. There is no doubt that that is OK.

I agree with Lou, the proposed method is not within code, and the best way is above using links. I'd spend the extra money to be within code, and not risk anything.

If you had a fire I believe because it was not up to code you insurance does not have to pay our if they can prove it.

 

[DIYHO]

This diagram is clearly taking the hot from one j box and using the neutral on the other jbox for the load, not just to power the leds on the switch. So if the hot/neutral on the second box are not on the same circuit as the first box, I don't see how this could be OK.

If you went to your panel and swapped your breakers around you could keep both hots on the same phase so the 240 thing could be avoided. But I don't know if that makes it OK for code.

I keep going back to putting two independent switches and linking them via UPB power line commands instead of hard wiring them together. There is no doubt that that is OK.

Please refer to my schematic. The one you are referring to is not an accurate depiction of the install.

View attachment 3614

For reference sake, the circuits are both on the same phase.

Since there seems to be some confusion over the Simply Automated wiring diagrams, I'd like to point out that to the best of my knowledge none of the (unmodified) Simply Automated diagrams represent two circuits. The two circuit setup is not diagrammed in any of the Simply Automated user guides, or at least I have not seen any.

The one I modified above does show the two circuit setup as I believe was detailed in the optional step 7 of the instructions.

 

[Digger]

This diagram is clearly taking the hot from one j box and using the neutral on the other jbox for the load, not just to power the leds on the switch. So if the hot/neutral on the second box are not on the same circuit as the first box, I don't see how this could be OK.

If you went to your panel and swapped your breakers around you could keep both hots on the same phase so the 240 thing could be avoided. But I don't know if that makes it OK for code.

I keep going back to putting two independent switches and linking them via UPB power line commands instead of hard wiring them together. There is no doubt that that is OK.

Please refer to my schematic. The one you are referring to is not an accurate depiction of the install.

View attachment 3614

And just for reference, the circuits are both on the same phase.

This is not sharing a NEUTRAL between two circuits it is sharing a HOT between two neutrals from what I interpret the schematic The load is on the hot and Neutral 1 but the LED's for the slave switch are using Neutral 2 not Neutral 1. If the load from the LED's was high enough and downstream of a GFCI on Netutral 2 circuit then it would trip the GFCI.

I am honestly not sure if this meets code or not. I do not think it is a hazard but I would have to spend more time looking at it from that perspective to be more comfortable with it.

Personally I agree with Lou and use two switches in virtual linking if you want to be 100% sure.

 

[TurboSam]

It seems to me that this just screams for a virtual three way (as Lou and Digger have both suggested) using two SA switches instead of one switch and the US-40.

You can use two of the three traveler wires to get a hot and neutral to the remote location and then power the load off either side with a same-circuit netural and without any worries about code or fires.

Take a look at the wiring diagram in the attachment to Event5's post number 9 in the "Simply Automated 3 Way Hook Up" thread from earlier this year. SA 3 Way Diagram

And let me add kudos to Ken and Millard at SA who were extremely helpful last week when I was struggling with a remote location without a hot or a neutral.

Sam

 

[Sandpiper]

Here is a schematic of the setup that is accurate. The other one was close, but not quite.

Thanks for the picture. My analysis of this is that it would be safe, but maybe not technically to code. The neutrals are not tied together (good), but a small amount of current is allowed to pass from the hot of one circuit to neutral of another. This is, the LEDs inside the switch take current from one circuit and return the current to the neutral of another circuit. This is a small amount of current, but I am not sure it technically meets code. There are probably many code enforcers out there who would say this is not to code. Maybe Simply Automated has got this cleared from some authority, I dont know.

I would not be concerned if this exact setup were in my house, but I would be concerned to tie two neutrals together as the Simply Automated sketch shows.

 

[DIYHO]

It seems to me that this just screams for a virtual three way (as Lou and Digger have both suggested) using two SA switches instead of one switch and the US-40.

If the LED indication will work as a 3-way, then I agree it would be far easier. Problem is, I already have over $200 of USR-40A's installed, so I would have to ditch those, then fork out the cash for US-240's replacements, just to get a simple single rocker 3-way switch.

Given the UPB stuff has already totally over 3K, and I still haven't purchased everything ... I would really rather not go that route unless there is absolutely no other solution. I've got many more "toys" to install and the money would be better spent on those.

You can use two of the three traveler wires to get a hot and neutral to the remote location and then power the load off either side with a same-circuit netural and without any worries about code or fires.

So far, I have not had a box without some type of incoming power. I do have one in the hall, however that particular 3-way will not present the 2 circuit problem.

Take a look at the wiring diagram in the attachment to Event5's post number 9 in the "Simply Automated 3 Way Hook Up" thread from earlier this year. SA 3 Way Diagram

And let me add kudos to Ken and Millard at SA who were extremely helpful last week when I was struggling with a remote location without a hot or a neutral.

Yes, I have seen that doc (it is supplied by Simply Automated), however I don't have a problem setting up virtual 3 ways, and I have already set some up for other purposes.

 

[DIYHO]

I would not be concerned if this exact setup were in my house, but I would be concerned to tie two neutrals together as the Simply Automated sketch shows.

I edited my post above to note the diagrams in the install docs supplied by Simply Automated do not indicate two different circuits so they are not showing a code violation.

So to avoid extreme confusion here for other readers it should be made clear that the Simply Automated docs do not show any type of 2 circuit setup to the best of my knowledge with regard to the USR-40A and the US2-40. Those damn schematics are hard enough to understand ..... the bleeding eyes kind :lol:

The one I posted is a modified schematic, not one supplied by Simply Automated.

 

[Sandpiper]

I would not be concerned if this exact setup were in my house, but I would be concerned to tie two neutrals together as the Simply Automated sketch shows.

I edited my post above to note the diagrams in the install docs supplied by Simply Automated do not indicate two different circuits so they are not showing a code violation.

So to avoid extreme confusion here for other readers it should be made clear that the Simply Automated docs do not show any type of 2 circuit setup to the best of my knowledge with regard to the USR-40A and the US2-40. Those damn schematics are hard enough to understand ..... the bleeding eyes kind :lol:

The one I posted is a modified schematic, not one supplied by Simply Automated.

I went to the Simply Automated site and read this entire document. They do clarify the situation with this note:

7. OPTIONAL: In some multi-way circuits there may not be an
‘always hot’ wire available in both junction boxes, requiring use
of one of the wires in the traveler Romex to provide a hot
connection to the other junction box, or possibly the hot wire of
an adjacent switch in the same junction box as the remote
USR. All hot power wires used MUST be powered from the
same circuit breaker.

The key point is "MUST be powered from the same circuit breaker", this implies that neutral is also from the same circuit. In this case, the wiring would be perfectly acceptable to the NEC. The problem occurs when the neutral is NOT from the same circuit, which is what I thought this whole discussion was about..........

 

[Sandpiper]

The reason for having to do this is because the remote box does not have power coming into it from the same circuit. So I am using the white as hot to bring power from the same circuit, and tying the neutral into the other circuit that is in the box.

This is from the original post. Indeed two circuits are involved.

 

[DIYHO]

The key point is "MUST be powered from the same circuit breaker", this implies that neutral is also from the same circuit. In this case, the wiring would be perfectly acceptable to the NEC. The problem occurs when the neutral is NOT from the same circuit, which is what I thought this whole discussion was about..........

Yes, that is what it is about, however as I already noted in a previous post, the docs make a specific point to say the hot must be on the same circuit, they don't make the same clear distinction with the neutral. Then they go on to explain how you can get a hot feed into the remote box that already has another neutral available by using one of the travelers. I would assume here that if there is already a viable neutral available in the remote box, then there probably is also a hot, just not one from the same circuit. Perhaps I am misreading it, but that is how I understand what was written after reading it many, many times.