2 circuits seemingly tied together questions

[borgdog]

So we recently moved into a new to us house, built in 1988, which besides having the bare minimum of circuits, also seems to have 2 of them connected somewhere.

I've been replacing outlets and switches as needed (adding timers to bath fans, replacing wired 30+ yo smoke detectors, and such) and ran into a couple where I have to turn off 2 breakers in order to not have power in those boxes. In both of those cases I disconnected everything turned the breakers back on and tested to see where power was, in each case only 1 wire had power.

Am I correct in thinking that I would only be seeing this if a hot from each circuit was tied together somewhere? Neutrals tied together would not show this right?

Also, besides being annoying is there any real hazard of not finding this immediately? The prior owner had the house for 34 years and as far as I can tell upgraded/touched nothing electrical beyond the permitted/hired addition of a hot tub circuit.

The circuits in the panel are labeled 'Lighting' and 'Kitchen Lighting'. I have found out the circuits labeled 'Lighting' also include the outlets throughout the house as there are no circuits labeled 'Outlets' but there are a couple 'Kitchen Outlets' which I have yet to confirm are what they say they are.

Thanks for your help/advice.

 

[walta]

I am not sure what you are saying.

#1 There is one or more lights or other loads that will operate unless two different breakers are both off if either of the two breakers is on the light /load all continue to work.

#2 You have discovered the power from two different breakers is present in the same switch box controlling separate light/loads.

If statement #2 is true I think that is normal and correct.

If statement #1 is true I would disconnect every wire connection on the two circuits Ohm out the wire so I understand where each wire comes from and reconnect them correctly and test the statement #2 is now correct.

Walta

 

[BillK]

#2 You have discovered the power from two different breakers is present in the same switch box controlling separate light/loads.

Thats what I was thinking too.

 

[sparky 1971]

So we recently moved into a new to us house, built in 1988, which besides having the bare minimum of circuits, also seems to have 2 of them connected somewhere.

I've been replacing outlets and switches as needed (adding timers to bath fans, replacing wired 30+ yo smoke detectors, and such) and ran into a couple where I have to turn off 2 breakers in order to not have power in those boxes. In both of those cases I disconnected everything turned the breakers back on and tested to see where power was, in each case only 1 wire had power.

Am I correct in thinking that I would only be seeing this if a hot from each circuit was tied together somewhere? Neutrals tied together would not show this right?

Also, besides being annoying is there any real hazard of not finding this immediately? The prior owner had the house for 34 years and as far as I can tell upgraded/touched nothing electrical beyond the permitted/hired addition of a hot tub circuit.

The circuits in the panel are labeled 'Lighting' and 'Kitchen Lighting'. I have found out the circuits labeled 'Lighting' also include the outlets throughout the house as there are no circuits labeled 'Outlets' but there are a couple 'Kitchen Outlets' which I have yet to confirm are what they say they are.

Thanks for your help/advice.

I don't know how it happens, but it happens quite often. Two circuits from the same phase somehow get tied together. It may be in a junction box that's easy to get to. If not, the easiest thing to do is to "break" a splice, cap one of the hot wires off and shove it to the back of the box, then you should have two separate circuits. Ideally, you will have about equal openings on each circuit which will probably require some trial and error as far as what splice to break.

 

[borgdog]

I am not sure what you are saying.

#1 There is one or more lights or other loads that will operate unless two different breakers are both off if either of the two breakers is on the light /load all continue to work.

#2 You have discovered the power from two different breakers is present in the same switch box controlling separate light/loads.

If statement #2 is true I think that is normal and correct.

If statement #1 is true I would disconnect every wire connection on the two circuits Ohm out the wire so I understand where each wire comes from and reconnect them correctly and test the statement #2 is now correct.

Walta

#1 is definitely what is currently happening.

I have not yet been in all the boxes, and have yet to find a box with both circuits on separate wires in it (#2 box). There are 4 circuits labeled lighting that feed all the lights and outlets in the house (4bed, 2300sqft), and there are 4 circuits labeled kitchen, one of which is one of the trouble circuits.

 

[walta]

Do you have any outlet adaptor like the one in the photo?

Walta

 

[BillK]

Just curious . . . . how are you checking for power ?

 

[dave*99]

You asked if this was unsafe. In a word, yes. You have 2 breakers feeding the same wire. So you could potentially draw double the rated current on that wire or: 2x15 or 2x20 or 15+20 depending on the breaker ratings.

I would leave one of the 2 breakers feeding that circuit off until you get it sorted.

 

[borgdog]

Do you have any outlet adaptor like the one in the photo?

Walta

No

 

[klassenl]

You asked if this was unsafe. In a word, yes. You have 2 breakers feeding the same wire. So you could potentially draw double the rated current on that wire or: 2x15 or 2x20 or 15+20 depending on the breaker ratings.

I would leave one of the 2 breakers feeding that circuit off until you get it sorted.

I don't follow. Could you diagram that for me.

 

[borgdog]

Just curious . . . . how are you checking for power ?

For outlets with a plug in tester, for lights if the light is on, but when I have everything open I have a non-contact tester wand thingy (whatever the technical name is)

 

[BillK]

For outlets with a plug in tester, for lights if the light is on, but when I have everything open I have a non-contact tester wand thingy (whatever the technical name is)

I think I would want to use an actual volt meter before condemning things. You might be getting "ghost" readings with those things. This stuff has all been working for 34 years with no problems.

How about a picture of the box in question showing the wires ?

 

[borgdog]

ghost readings wouldn't keep the lights on if only one of the breakers is off though.

so far I've been in 4 boxes on this combined circuit, 2 were smoke detectors with interconnect, others were lights in bathrooms that also had fan switches in them as well. in all cases if I disconnect all the wires I only have had 1 wire that shows power, and the only way to not show power is to turn off both breakers.

I've identified what I think is all the lights and outlets that are on this circuit and will be going through 1 box at a time until I find one with 2 hot feeds.. at least that's what I'm expecting to find somewhere. hopefully there is not a junction hiding.

 

[LXCam]

Do you have any switched receptacles?

 

[borgdog]

Do you have any switched receptacles?

Yes, living and family room both have switched receptacles, with top outlet always hot, bottom switched. I don't believe either of those are on the 2 breakers I have issue with though.

 

[LXCam]

I’d suggest double checking. There’s always a possibility someone screwed up and ran both a receptacle circuit and lighting circuit to a plug and also failed to break the tap off the recep.

If that’s a no go try to identify the closest junction box for the home runs and start disconnecting your hot leads and test, but you’ll need a multimeter to go down this road.

 

[justsam]

The two breakers in play, are they on top of one another, across from one another? Perhaps a picture of the breakers in the panel.

 

[borgdog]

the two breakers with blue tape on them. the labels on the door have the one on the left as 'Lighting', the one on the right 'Kitchen Lights'

 

[dave*99]

I don't follow. Could you diagram that for me.

 

[Damon L.]

What happens if you leave one off?

 

[dave*99]

What happens if you leave one off?

The receptacles remain live. The issue is that you could draw 30A from one of the receptacles if both 15A breakers are on. The wire is not rated for 30A and it could overheat.

 

[borgdog]

What happens if you leave one off?

I turned one of them off and as far as I can tell everything is working fine. Will leave this way for now until I have time to dig into more boxes and find the problem child.

Thanks everyone for the responses and suggestions. Will update when I find something.

 

[larry4406]

If you identified the dual feed, and confirmed that one or the other safely and properly powers the circuit, then why not just disconnect the black wire from one breaker of choice, wire nut it off in panel, and label it as live part of the retained breaker circuit?

 

[wyliesdiesels]

looks like theyre on the same phase...

 

[Zeke]

If you identified the dual feed, and confirmed that one or the other safely and properly powers the circuit, then why not just disconnect the black wire from one breaker of choice, wire nut it off in panel, and label it as live part of the retained breaker circuit?

He might end up with 30 or so devices on a circuit. It has held to date because it's been drawing over a pair of wires.

 

[Wrench97]

Shared neutral maybe?

 

[sparky 1971]

Shared neutral maybe?

No

 

[larry4406]

He might end up with 30 or so devices on a circuit. It has held to date because it's been drawing over a pair of wires.

Good point.

Couldn’t he just count the number of devices, go find a daisy chained outlet seemingly in the middle, then break the chain there?

After that assess the split achieved.

 

[justsam]

Sounds like right now you have two feeds from the same side of the split phase. Move a breaker around at some future date and you can wind up with them on different sides of the split phase and you will have a 240 VAC short. Probably no harm as breakers will trip, but it will get your attention.

 

[borgdog]

Finally ran across the box that had the two circuits connected today. Had 2 feeds coming into a 3 switch box by the front door. One of the switches was for a entry light (3 way) another for outside lights, and a third for a couple outlets in the front living room. Separated them there (one for the 3-way since that's where one came in, the other for the rest) and all is working well! Buy a new (to you) house and you never know what weird stuff you are going to find, cross this one off the list, still need to replace all the loose 30+ year old outlets, but making my way one project at a time.

Thanks again everyone for the words of wisdom.

 

[FredWanaker]

good job. Took perseverance to solve.