Simply Automated Switches & Sharing Neutrals

[DIYHO]

Hello all,

I am in the process of rebuilding my house, and have finally got to finish wiring. What I am finding is my electrician didn't wire the place the way I specified, and I am having to jump through hoops to make hardwired 3-way/multi-way wiring work. I should have checked his work, but didn't, and now am regretting it.

So on to the issue with neutrals and simply automated US2-40 and USR-40a.

I have wired everything up, but in order to get the USR to work, I was forced to use the neutral as hot in the 3 cond. traveler wiring for several switches and using an available neutral in the remote electrical box. 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.

Now I know that sharing neutrals is generally frowned upon unless the circuit is designed from the beginning that way. That said, is this type a setup really a "shared neutral" and is it a NEC code violation. This is the method recommended by SA for getting power from the same circuit to the USR, however they did not note the neutral tie in had to be on the same circuit like the hot does.

I do have a picture of one of the setup and will post it if that will help once I am allowed to attach images.

 

[IndyMike]

Hello DIYHP,

The easy question first: "Is this a NEC code violation" - YES

Beyond being a code issue, this really is a Safety issue. You do not know what other items are on the circuit that you've tied into, or what phase the circuit is on.

Worst case - you've tied into a neutral that is being used as the return for the opposite phase. If the neutral is interrupted while a load is on, the neutral voltage will be pulled to the opposite phase supply (120V). Since the line to your switch is on the opposite phase, the total voltage across the switch will now be 240V. Bad things will happen - hopefully they won't involve the fire department.

The above is only one example of failures that can occur. The NEC code was developed to protect us against these type of failures. Please follow it.

 

[Digger]

IndyMike is correct from what you describe this is a code violation and safety hazard.

I would call back the electrician and have him correct the wiring to what you had specified (hopefully it is in writing).

 

[JonW]

It sounds like the OP is using the WHITE wire as a traveler between the main and remote switches. It is not a NEUTRAL wire unless it is actually connected to the NEUTRAL distribution of the house. By code, an insulated wire can be reused for another purpose if it is adequately marked as such. Normal methods of marking would be to wrap colored electrical tape around the visible portion of the wire in the J-box.

 

[Digger]

It sounds like the OP is using the WHITE wire as a traveler between the main and remote switches. It is not a NEUTRAL wire unless it is actually connected to the NEUTRAL distribution of the house. By code, an insulated wire can be reused for another purpose if it is adequately marked as such. Normal methods of marking would be to wrap colored electrical tape around the visible portion of the wire in the J-box.

Jon look at this statement made by the original poster

I have wired everything up, but in order to get the USR to work, I was forced to use the neutral as hot in the 3 cond. traveler wiring for several switches and using an available neutral in the remote electrical box. The reason for having to do this is because the remote box does not have power coming into it from the same circuit.

 

[DIYHO]

Hello DIYHP,

The easy question first: "Is this a NEC code violation" - YES

Beyond being a code issue, this really is a Safety issue. You do not know what other items are on the circuit that you've tied into, or what phase the circuit is on.

I do know what each circuit does and what phase it is on.

The confusion is this. According to the user guide I do not need to connect the USR neutral or line leads to anything, connection is only required to operate the LED's indicators (i.e. matched LED indication with the master switch). Here are the appropriate sections from the USR-40A user guide so you can perhaps see the confusion.

http://www.simply-automated.com/documents/...uide_100624.pdf

2. If power is not available at the USR, only the green LED will
function. If a neutral wire is available in the remote USR
junction box (e.g. neutral wire from a power feed to an adjacent
switch), other than the white wire in the traveler Romex or the
white neutral wire going up to the load/lights, then one of the
wires in the traveler Romex (e.g. white wire) maybe re-labeled
(as black) and used to carry power (hot) over to the USR to
enable the blue LED function. See step 7 for more details.

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.
CAUTION: DO NOT USE A HOT POWER WIRE FROM
ANOTHER CIRCUIT-BREAKER TO POWER THE
REMOTE USR. Injury or permanent damage to the
device may result. Improper installation voids the
product warranty. The master load controlling switch and
the remote USR must be powered by the same circuit-
breaker.
If a neutral wire is available in the remote USR junction box
(e.g. neutral wire from a power feed to an adjacent switch),
other than the white wire in the traveler Romex or the white
neutral wire going up to the load/lights, then the white neutral
wire in the traveler Romex maybe re-labeled (as black,
typically with black electrical tap on white wire insulation at
both ends) and used to carry power (hot) from the master
switch junction box over to the USR to enable the blue LED
function.

Worst case - you've tied into a neutral that is being used as the return for the opposite phase. If the neutral is interrupted while a load is on, the neutral voltage will be pulled to the opposite phase supply (120V). Since the line to your switch is on the opposite phase, the total voltage across the switch will now be 240V. Bad things will happen - hopefully they won't involve the fire department.

I thought when sharing neutrals you want circuits to be on the opposite phase so the neutral currents will cancel, although I also understand the potential problem as you have indicated here as well.

 

[DIYHO]

It sounds like the OP is using the WHITE wire as a traveler between the main and remote switches. It is not a NEUTRAL wire unless it is actually connected to the NEUTRAL distribution of the house. By code, an insulated wire can be reused for another purpose if it is adequately marked as such. Normal methods of marking would be to wrap colored electrical tape around the visible portion of the wire in the J-box.

Yes. I have re-purposed (and marked appropriately) the neutral (white) in the traveler romex in order to bring a hot feed from one circuit into a box that doesn't have a hot feed for the same circuit.

 

[IndyMike]

Hello again DIYWP,

I'm rather happy to see that you've taken the time to determine which phase you are stealing the neutral from, and what is on the circuit. My initial reply may have sounded harsh - but it's the reply I would have given to anyone with the information presented.

Worst case - you've tied into a neutral that is being used as the return for the opposite phase. If the neutral is interrupted while a load is on, the neutral voltage will be pulled to the opposite phase supply (120V). Since the line to your switch is on the opposite phase, the total voltage across the switch will now be 240V. Bad things will happen - hopefully they won't involve the fire department.

I thought when sharing neutrals you want circuits to be on the opposite phase so the neutral currents will cancel, although I also understand the potential problem as you have indicated here as well.

What you are describing is a completely different installation. The Code allows for 240V three wire runs (14/3 or 12/3) where the circuits are then split into two 120V branches. The current on the neutral is then shared between the two 120V phases. There are many additional requirements that apply to this configuration to satisfy safety constraints (load balancing, etc). As of 2008 (I believe), the circuit is required to be controlled through a single double pole breaker.

I do know what each circuit does and what phase it is on.

The confusion is this. According to the user guide I do not need to connect the USR neutral or line leads to anything, connection is only required to operate the LED's indicators (i.e. matched LED indication with the master switch). Here are the appropriate sections from the USR-40A user guide so you can perhaps see the confusion.

I've done a quick read on the document you provided and agree it's confusing (particularly when they refer to page 7 for "details" in a 4 page document). I will agree that the document implies that you don't require a line or neutral at the remote switch (depending on your configuration), but would like others with direct experience to comment.

If the switch will function (signal the master) properly without the neutral connection, the installation would get a clean bill of health (not sharing the neutral).

In the end, the decision is yours to make. If you elect to share the neutral (same phase), you will be adding an insignificant current to the neutral on that branch. However, you will be opening yourself up to other failure modes (throwing the breaker on that circuit will not kill the current on the return, lightning concerns, possible noise concerns). If I were an inspector I would still "red tag" the box and make you demonstrate that it wasn't a problem. Since I'm not an inspector (you're the inspector on this job), you need to satisfy yourself that this is a safe, acceptable installation.

Personally, if the switch will operate without the neutral connection (TBD), I would err on the side of caution and give up the LED.

IM

 

[DIYHO]

Here is a pic of the worst box in the house, maybe this will help understand the mess.

Red arrow indicates power into box, which had to be used to power living room receptacles given the electrician didn't wire the feed to those into the appropriate box. I can easily put this circuit on either phase and supplies the neutral back to the sub-panel. Everything in the box is tied into this neutral.

Green arrows indicate the re-purposed white (neutral) wire in the traveler romex. Each one is providing power from a different circuit.



Switches explained starting from the left.

1) US2-40 - Scene control, no attached load. This is getting hot power from the middle lighting circuit. (middle green arrow)

2) USR-40A - Remote switch, no load. This is getting hot power from the same circuit as the master switch (middle green arrow)

3) US2-40 - Load is a single exterior light, 3-way to box in garage and will get power from that garage box via the re-purposed white (neutral) in the traveler romex. (right green arrow)

 

[DIYHO]

I've done a quick read on the document you provided and agree it's confusing (particularly when they refer to page 7 for "details" in a 4 page document). I will agree that the document implies that you don't require a line or neutral at the remote switch (depending on your configuration), but would like others with direct experience to comment.

If the switch will function (signal the master) properly without the neutral connection, the installation would get a clean bill of health (not sharing the neutral).

In the end, the decision is yours to make. If you elect to share the neutral (same phase), you will be adding an insignificant current to the neutral on that branch. However, you will be opening yourself up to other failure modes (throwing the breaker on that circuit will not kill the current on the return, lightning concerns, possible noise concerns). If I were an inspector I would still "red tag" the box and make you demonstrate that it wasn't a problem. Since I'm not an inspector (you're the inspector on this job), you need to satisfy yourself that this is a safe, acceptable installation.

Personally, if the switch will operate without the neutral connection (TBD), I would err on the side of caution and give up the LED.

IM

Thanks for the reply Mike.

Currently the switch does function properly and shows correct LED status. I haven't tried disconnecting the neutral and hot from the remote switch, but based on the docs, I assume this will effectively kill the blue LED status indication.

The docs are a bit confusing, especially given the wording makes a clear distinction between hot and neutral, yet only indicates the hot needs to be on the same circuit. This is what has caused me to hesitate given concerns about tying neutrals together from two different circuits.

Oh, and this will be inspected by the city during the final inspection and I haven't failed one yet given my propensity for over kill, nor have any of the contractors I had come in to do some of the bigger jobs. It would be nice to finish this massive rebuild with a perfect inspection record.

 

[tmbrown97]

Worst case - you've tied into a neutral that is being used as the return for the opposite phase. If the neutral is interrupted while a load is on, the neutral voltage will be pulled to the opposite phase supply (120V). Since the line to your switch is on the opposite phase, the total voltage across the switch will now be 240V. Bad things will happen - hopefully they won't involve the fire department.

I've actually seen this happen - a good friend of mine had a wire nut come loose causing this - and basically all the appliances on one circuit got hit with 240 and fried (gas stove, fridge, etc). Very rare occurrence though.

You are correct that the USR absolutely does not require a neutral - in fact, it only requires a single wire - the traveller, to function. The documentation on the USR's is extremely confusing - I'll be posting an article soon that clears a lot of up based on my own experience. The lights are way more flexible than the docs show.

I've done some pretty trick wiring at times to get my UPB switches where I want them, including sending power/neutral downstream, and/or using multiple 1140's/240's and no remotes to accomplish my goals. It's nearly always possible to get something working.

Unfortunately, in my current install, I had to give up a couple LED's just because I didn't have a Hot from the same circuit - but such is life... Better to be safe. Glad you followed the basics and used electrical tape to re-code the neutrals - that's perfectly acceptable. Good luck on the inspection.

**I'll be really interested in hearing how your inspection goes - these switches are wired much differently than normal circuits, so it may be hard for your inspector to comprehend. Many electricians just don't get them. And while this is never officially recommended, it's always an option to wire things conservatively for the inspection, then make an educated decision to experiment afterwards.

 

[Sandpiper]

Worst case - you've tied into a neutral that is being used as the return for the opposite phase. If the neutral is interrupted while a load is on, the neutral voltage will be pulled to the opposite phase supply (120V). Since the line to your switch is on the opposite phase, the total voltage across the switch will now be 240V. Bad things will happen - hopefully they won't involve the fire department.

I've actually seen this happen - a good friend of mine had a wire nut come loose causing this - and basically all the appliances on one circuit got hit with 240 and fried (gas stove, fridge, etc). Very rare occurrence though.
[snip]

No, this is not the worst case, it is the BEST case for this situation. As DIYHP pointed out, the neutral CAN be shared, according to code, if the hots are on opposite phases. Sharing neutrals for circuits on the same phase is a fire waiting to happen. Sharing neutrals on circuits with hots on the opposite phase is called a multi-wire branch circuit in the NEC.

A multiwire branch circuit can be hazardous, however, in certain situations, one of which was pointed out by IndyMike and Work2play. Yes, if a neutral is lifted while now of both hots are still closed, you will get 240v across the neutral gap. This could be hazardous, or it may not be, but it will not fry your switch. In any case, the NEC code has been recently changed to require multi-wire branch circuits to be powered from a double pole breaker, where before individual single pole breakers could be used. This new requirement does reduce the hazards for this type of circuit quite a bit.

 

[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.

 

[DIYHO]

Thanks for the replies guys,

Did some testing last night, this is what I came up with by disconnecting various wires and using my current detector.

When wired per above pic, everything works as it should with full LED function. No current is detected on the neutral lead of the switch or any other neutral in the box.

1) Disconnect hot (black) leads on USR switch

1. No power on hot lead from switch when light is on
2. USR will turn light on and off
3. only green LED works when light is on
4. no blue LED when light is off

2) Disconnect both hot (black) and neutral (white) leads on USR switch

1. Power on both hot and neutral leads when light is on, no power on hot and neutral leads when off
2. USR will only turn light on, but not off
3. no LED function at all

No current was detected on any of the neutrals connected by the blue wire nut in any of the above cases regardless of 1 or both circuits being powered up.

It appears I need at least a neutral connection to get the USR to work properly, which isn't a problem if I am willing to lose blue LED functionality. I might note here the result of test 2 would appear to be inconsistent with the USR-40A user guide.

I still am unsure if the wiring in the neutral of the switch to another circuit is going to cause a problem because I am not exactly certain how the USR functions with regard to the hot and neutral leads on the switch. Safety (fire) is my primary concern here, so if it is possible to use the USR's and keep full LED functionality that would be ideal.

Although I haven't finished wiring up all the switches yet, I believe there are at least 5 boxes in the house that will need to utilize this type of wiring arrangement in order to achieve 3 way switching with full LED functionality on the USR (i.e. power in the remote box is not on the same circuit, and use the white in the traveler romex to bring in same circuit power). I would prefer to keep the hardwired 3-way switching since I already have the USR's and they are significantly cheaper than the US2-40's, which could be use as a last resort in a virtual 3-way setup.

@sandpiper

Yes, what I have read on shared neutrals and phases was in regard to multi-wire circuits. The problem I have been having with code interpretation is that this situation is not a true multi-wire circuit as both circuits have their own neutral, even if the neutrals between the two (in the above pic) are tied together through a switch.

 

[apostolakisl]

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.

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. 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 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.