DIY Home Improvement Forum banner
1 - 20 of 26 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter · #1 ·
I have a two gang box at my door to my attached garage. One switch for garage light, one switch for kitchen ceiling light. Both are three way switches. The power for both these lights are on the same circuit 8, but are provided at the other 3-way switch for each. From the other switches, they used older 2 wire cable and used the black and white as travelers coming to the door at the garage. This introduced the issue that there is no circuit 8 neutral present at the garage door area switches. So what was done, is that a small circuit nearby, circuit 11, was ran into this box just for the purpose of providing a neutral for the 3-way switches. On circuit 11, this sharing of its neutral is about midway in the circuit, with an outlet and light on one side, and two outlets on the side. Circuit 8 has alot of stuff on it, but in this area (with the neutral provided by circuit 11), it just has the kitchen ceiling light and the garage overhead light on it.
My question is how dangerous or problematic this could be, provided the following info. I understand how MWBC or "shared neutral" circuits work, and this appears to be a variation of a partial shared neutral circuit, but with the neutral not in the same cable as the ungrounded hot conductors. Also, I understand that either circuits neutral wires could remain "hot" with the breaker off, unless both breakers are off, so I have marked my panel and drawings accordingly. Also, that this might introduce EM leakage from the wires. Lastly, the two circuits in question are on opposite phases of my panel, so I imagine the current would cancel out, just as in a normal "shared neutral" circuit.
I understand this is not up to code or ideal, but it is working, and I want to make sure it is safe as long as I know about it and let any electrician I hire know also.
 

·
Registered
Joined
·
10,958 Posts
and I want to make sure it is safe as long as I know about it and let any electrician I hire know also.
It isn’t safe. That is the usual result of not following code.

You want to rely on your memory, no matter how busy you are, to inform an electrician X years from now. What are you going to do when you sell the house ? Inform the buyer?

What you should do is disconnect that bootleg neutral. If the circuit isn’t working, it will be a reminder to fix it.
“It works“ is never the standard for electrical work
 

·
Njuneer
Joined
·
1,577 Posts
Though not proper wiring, to increase safety, you may consider installing a double pole breaker running off opposing phases, which is proper for an MWBC.

Yes, as long as neutral is shared by opposite phases, the current cancels, no safety issue there.
 

·
Premium Member
Joined
·
4,347 Posts
Might pay to inspect all the other wiring in the house if you already haven't.
 

·
Registered
Joined
·
10,125 Posts
For a multiwire branch circuit, both hots and the neutral must be in the same cable or conduit.

If you create or leave intact the borrowing of a neutral for a different branch circuit you can create for the next owner of the house problems with hard to find ground fault circuit interrupter trips.
 
  • Like
Reactions: MTN REMODEL LLC

·
Registered
Joined
·
6,359 Posts
So what was done, is that a small circuit nearby, circuit 11, was ran into this box just for the purpose of providing a neutral for the 3-way switches.
Then make them the same circuit!

Since this "circuit 11" exists only to feed neutral to "circuit 8", then why are you putting it on a separate breaker? Why not combine it with circuit 8 and feed it from what I guess would be breaker 8?

I do that kind of thing all the time, have two legs of 1 circuit that go 2 different directions from the panel. Some breakers are listed for 2 wires on the terminal (Pushmatic and HOM come to mind), others you will need to pigtail.

I understand how MWBC or "shared neutral" circuits work,
I don't think you do lol, or at least, you are weirdly lacking in fear of consequences.

and this appears to be a variation of a partial shared neutral circuit, but with the neutral not in the same cable as the ungrounded hot conductors.
"variations" of "partial" are not good enough. Either it's a proper MWBC or it isn't. "MWBC variations" are one of the most dangerous things I see in panels.

I wouldn't have a problem with it "8" and "11" were a proper MWBC with correct phasing and a handle-tie because again, that would make them the same circuit. An MWBC is 1 circuit. However I suspect one of them is already a member of a different MWBC.

The "neutral not in the same cable" is a NEC 300.3 violation, but that is the least of my concerns here.

I have marked my panel and drawings accordingly.
I understand this is not up to code or ideal, but it is working, and I want to make sure it is safe as long as I know about it and let any electrician I hire know also.
LOL, safety does not work that way. It's been tried.


From the other switches, they used older 2 wire cable and used the black and white as travelers coming to the door at the garage.
OK, well that's F'd up crap work done by the previous hillbillies...

... but the answer there is smart switches, not violating code a bunch more. Use smart switches which are capable of wireless or powerline signaling. Insteon comes to mind.
 

·
Registered
Joined
·
848 Posts
This is the way it was often done before they required AFCI breakers. Actually 3 conductor wire was more expensive than 2-2 conductor wires so that was a money saving practice up until the copper price surge about 15 years ago. Then price of 3 conductor evened out proportional to the number of conductors.
 

·
Registered
Electrical, remodeling
Joined
·
629 Posts
The sharing of a neutral for has been common place for years.

How the circuits and their shared neutral are dealt with depends on when the home was built and what code was in effect at the time.

Can the current condition of how things are wired be dangerous to you?

Probably not.

Could it be dangerous for some unsuspecting person actually working on the wiring?

Possibly.

Where has this concern for EM "leakage" come from?

Any wire carrying a voltage creates an induced voltage on adjacent wires.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #11 ·
Thanks for all the answers. I was reading that by code, MWBC with shared neutral should be in the same cable as the 2 phases EMI cancel each other out, and no EMI interference will happen, just what I was reading about. Anyway, also I can't combine 8 and 11 because 11 is a seperate circuit with a few receptacles and lights on it. I probably could combine 8 and 11 in my basement, but 8 already has a TON of stuff on it (how it was when I purchased house, house built in 1963) and I don't want any more outlets on 8. Also, I have mapped all the circuits in my house when I purchased it 1 year ago, and I know where all the MWBC's are, to the best of my ability without removing drywall. I have replaced all the switches and receptacles in the house, made repairs at my panel where double tapping was going on, and replaced numerous dangerous connections in several switch boxes where a twisted splice was made with electrical tape instead of wire nuts. I am trying very hard to make this safe, so I don't appreciate some of the attitude.......I understand the switch doesn't require a neutral, but the light connected to it does, or it won't work. If this is indeed dangerous for ME, and I shouldn't even use it for a month while I wait for an electrician, please explain why it's dangerous. And some ideas to fix it. Like, should (can) I run new cable from another point in circuit 8 to these switches for the sake of neutral? Thanks again everyone.
 

·
Njuneer
Joined
·
1,577 Posts
You've said enough to force a proper shake down of your 'situation'. Anyone that replaces wire nuts with tape needs their tools taken away, so it would be proper to pop every lid you can find and try to sort the mess.

I offered you a solution, not because it is code compliant, but that it at least helps. Part of what makes an MWBC safe is the tie bar on two breakers next to each other, hopefully confirming they are on opposite phases, and knowing that if one is down, the other is as well.

only other solution is rewiring stuff. Sometimes an electrician onsite can comb through the madness faster than any Inet jockey can because they are there to see it. You don't seem incompetent with electrical and they will sell wire nuts to anyone, so......

We just don't know the extent of your MWBC circuits and if ANY of them have proper breakers. What really sucks with homes is they are not forced like commercial to produce an MEP plan with drawings. Even new homes are more or less a **** show if the installer has been on the crack pipe too long.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #13 ·
Thanks Viper. I have "popped every lid" to map my wiring. I did tie the handles on my other MWBC's, as they are right adjacent to one another. However, 8 and 11 are on opposite sides, so I can't tie them, I don't have enough wire inside panel to bring them to a double pole. From my mapping of the house electrical, it appears to the best of my ability, that my other MWBC's are all normal ones eg.. in the same cable, on opposite phases, and tied together at handles. I have 3 conventional MWBC's, and they are all powered by conventional 15a single space breakers (not double pole) that are adjacent (1&3, 2&4, 6&8) to each other so I was able to confirm they are on opposite phases, and I was able to tie their handles together. I don't know exactly what you mean by "proper" breakers for a MWBC, can you please explain that? I really wish I had drawings of the electrical, in fact I have made my own drawings showing how everything is routed, how everything is wired in panel, where everything runs as I discover it, how all my GFCI outlets are protecting downstream outlets as I had to do that due to not having a equipment ground in a lot of the original wire cables. I used a combination of free website floorplanner.com and good ol' Microsoft Paint. I have looked for a better program to use, but can't find one thats not expensive or way more than I need.
As a side note, I have been an Aircraft Maintenance Technician for 30 years, working on everything from Cessna Conquests to Boeing 747's. I am well versed in electricity, just not specifically home wiring. Again, thanks to everyone for your help.
 

·
Remodel and New Build GC
Joined
·
11,484 Posts
JETBOY.....

Just a comment that I personally applaud your work and effort to clean your electrical.

(And off the record, and as a GC, I've run into alot either old grandfathered stuff , or even outright incorrect wiring when it did not involve my remodel, and I chooze your "solution" to clearly identify it on the panel or as appropriate.

Perfect NO.... but an improvement yes. IMO

I don't remember code cycles of when MWBC had to be handle tied, or I think there was an era when just their panel feeds of red /black / white had to be "twist-tied". My personal production built home of 1996 is full of MWBC's slims that were not identified. I now have big blue tape on the dead front door identifying such that can't be missed by any semi competent individual. Perfect NO...but better Yes.

I do that even for strange wiring, that might be confusing to someone later. In a previous addition, the owner lost half his lighting in a master bedroom...took a long time to discover the problem...they had tapped into a convenient outside receptical for the lighting circuit.... which was on a worn out GFI way around the other side of the home behind some heavy bushes.

On a massive rebuild of my son's home, we ended up with a whole panel board of 4 square J's up in an attic hooking up old to new, ....I carry some nice Avery stickers to label each box. (On inspection, the BO loved it.)
 

·
Registered
Joined
·
3,532 Posts
If as you stated, you already have a MWBC for circuits 6 & 8, and now you are taking a neutral from circuit 11, hijacked it's neutral and pair it with the hot from circuit 8, to energize some devices, right?

If circuits 6 & 8 are on opposite phases, circuits 8 & 11 are on opposite phases, then 6 & 11 are on the same phases. Circuits 6 8 11 all share the same neutral. Even if you disregard the rule about using conductors in different cables, rule about handle ties, rule about having breakers adjacent to each other, aren't you essentially piggy backing the neutral for 6 & 11, they are now additive. I am not an electrician but if I have this issue I would have rather take the hot off circuit 11 and pigtail it to 6, at least that way the breaker will offer protection.
 

·
Njuneer
Joined
·
1,577 Posts
Thanks Viper. I have "popped every lid" to map my wiring. I did tie the handles on my other MWBC's, as they are right adjacent to one another. However, 8 and 11 are on opposite sides, so I can't tie them, I don't have enough wire inside panel to bring them to a double pole. From my mapping of the house electrical, it appears to the best of my ability, that my other MWBC's are all normal ones eg.. in the same cable, on opposite phases, and tied together at handles. I have 3 conventional MWBC's, and they are all powered by conventional 15a single space breakers (not double pole) that are adjacent (1&3, 2&4, 6&8) to each other so I was able to confirm they are on opposite phases, and I was able to tie their handles together. I don't know exactly what you mean by "proper" breakers for a MWBC, can you please explain that? I really wish I had drawings of the electrical, in fact I have made my own drawings showing how everything is routed, how everything is wired in panel, where everything runs as I discover it, how all my GFCI outlets are protecting downstream outlets as I had to do that due to not having a equipment ground in a lot of the original wire cables. I used a combination of free website floorplanner.com and good ol' Microsoft Paint. I have looked for a better program to use, but can't find one thats not expensive or way more than I need.
As a side note, I have been an Aircraft Maintenance Technician for 30 years, working on everything from Cessna Conquests to Boeing 747's. I am well versed in electricity, just not specifically home wiring. Again, thanks to everyone for your help.
"Proper" means double pole or otherwise tied. Look up NEC 210.4b
It becomes common sense that if two circuits share a neutral, both circuits must be taken down for service of either circuit for safety. Thus the handle tie.

I want to say Sketchup can do some MEP plans in it. We don't use it, but many do.
 

·
Super Moderator
Joined
·
17,342 Posts
I am still missing why you are trying to get a neutral for a switch.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #18 ·
Thanks miamicuse, your comment brought to light that with 6 & 8 being together in MWBC, that puts 6 and 11 sharing a neutral through the tie in with 8, so yeah, they would be additive, which is definitely bad. I will immediately start looking for a solution. Switching 11's outlets over to 6 will get me back to opposite phases, and might be the solution I will use. I don't want to use a pigtail with wire nut inside my panel, so I will see where I can tie 11 into 6 somewhere in my basement. At least that way I wont overload my neutral and cause a fire...........As far as needing a neutral for a switch, I don't. But I do need a neutral at that switch box because that is where the cable that goes to the light comes, and it needs a neutral to light up after I turn on the switch.
 

·
Registered
Joined
·
3,532 Posts
I don't want to use a pigtail with wire nut inside my panel
There is no issue with pigtailing with wire nuts inside a panel. There are times the wire is too short to reach a breaker and you need to extend a conductor. There are times a circuit splits into two leaving two conduits to opposite walls and require a pig tail. I try not to do it but sometimes not avoidable. This is why I hate it when electricians cut the conductors just the "right" length to reach a breaker for the sake of "neatness".
 
1 - 20 of 26 Posts
Top