Strange occurence on home circuit

[bogie002]

Hello,

Im new to the forum. Looks like lots of great information!

I am currently remodeling a laundry room in a house I bought about a year ago. Im not sure if this is typical procedure or not however, I have one wire (black cover housing a red, black, white, and bare ground wire). I believe this wire is normally used for 3 way switches, switch controlled outlets and such. In this situation, it appears this one wire is coming from the fuse box bringing power from what I will call the 8 and 9 circuits (Red Wire #8, black wire #9). The #8 circuit seems to be working normally.

The #9 circuit seems a bit strange to me. From what I can tell, the power feeds through a switch to the laundry vent fan then continues on to another room. I disconnected all wires at the switch. I reset the breaker and using a circuit tester, the incoming #9 wire is hot and nothing beyond this point is working as it should not. The strange thing is the wire that appears to be continuing along the circuit. Nothing on that circuit is working however, I show current when touching the circuit tester from the white to the ground, from the black to the ground, but not from the white to the black.

It seems like something maybe crossed with another circuit??? Now, having said all that, everything was working fine. I new something was strange when arcing occured while disconnecting the white wires which were all tied together at the switch. Everything works but, do I have a situation needing further attention?

Thanks

Bogie

[HayZee518]

The white wire will show sparks as something else in the circuit is operating. The white isn't always necessarily at ground potential. In this case it is carrying the unbalanced load to ground. Kinda hard to fathom this, I know, butthat's the nature of the beast.

[bogie002]

I dont really understand this. I always thought that one breaker went to one circuit. And, if you trip that breaker, there will be no current traveling through that circuit.

I need to reroute this wire in question. I tested this wire the hard way already and though it appears to be a lower voltage, I didnt like it[B)]. Should I look for another breaker, turn the whole thing off or, maybe just wrap them with some tape?

Bogie

[kactuskid]

Do you have fuses or breakers? The type of circuit you are describing, where there is a 3 wire cable comming directly from the main panel is a multi-wire circuit. These types of circuits are very dangerous cause they are actually 2 circuits that share the same neutral wire. So, this means that each hot wire is connected to a different breaker (as in your 8 and 9) But, these breakers should have a handle tie between them so that they are both shut off at the same time. The reason for this is cause these two circuits are 180 degrees out of phase with each other and therefore you have 240 volts potential between the two hot wires in each and every box on this circuit.

So, you need to make sure you install a handle tie between these two breakers and you need to make sure that if there are any receptacles on this circuit, that the neutral wires are connected together with a wire nut and a pigtail is fed to the receptacle. This way the neutral wire won't have a chance of opening up which could be very dangerous.

Here's a link that'll give you some details about them, if you have more questions ask back.

http://ourworld.compuserve.com/homepages/boyce_smith/multiwir.htm

[bogie002]

Hi kactuskid! These are breakers not fuses. I think what you mentioned is exactly what I have. I guess my next question is how do I fix it. The 2 breakers are not tied together. I still dont understand how there is still current flowing when both breakers are turned off. But, I always compare a breaker to the kitchen faucet. Turn it on if you want water and turn it off if you dont.

From reading the info on the link you posted and what you have said it looks like I have a few options. Replacing the breaker with a dual pole breaker. Or, running another wire and sperate the two circuits. I guess running another wire would be best?? What's your opinion?

Thanks so much for the info!

Bogie

[kactuskid]

Hi Bogie, yu can't just run another wire, though this would seem the easiest way, it's just not legal to do. You would need to remove the 3 wire cable and run two cables of either 14/2 or 12/2 and connect each to a separate breaker. Your best alternative here would be to install a double pole breaker and connect each hot lead to the breaker. This is the normal way this is done.

I don't understand when you say you still had voltage. If both breaker are open then you should have no voltage on these wires. You may need to remove the main panel cover and verify that just one hot wire is connected to each breaker. With the breakers closed, you should read 240 volts when measureing across both hot leads. I also think if you're doing some additional remodeling that you should run a new circuit instead of trying to tap power from this multiwire circuit, that would be your safest route.

I'm gonna provide you below with alot of information about multiwire circuits. This info comes straight from an expert and should fill you in on all the details about multiwire circuits. Hope this helps, and please ask back with any questions.

MULTIWIRE BRANCH CIRCUITS 12-3G AND 14-3G


MULTIWIRE CIRCUITS USING 12-3G ETC ARE NOT A RECOMMENDED WIRING METHOD FOR DIY.

BUT "DIY" WILL COME ACROSS THESE ..VERY/VERY/VERY OFTEN..SO MUST COME TO UNDERSTAND THEM!!

300-3.b..."all conductors of the same circuit shall be contained within the same raceway or cable.."..
..if not, we risk overheating.

More on these 120volt ,three conductor 'multi-wire' ,SHARED /COMMON/NEUTRAL branch circuits ,that appear to be 240v (208v) circuits at first glance,and how they apply to residences

THEY ARE 120V CIRCUITS!...ONLY [Generally]
They are generally ran using 14-3G and 12-3G NM-B cable.


Multi-wire branch circuits are permitted by 'the' code...but DIY are usually advised to avoid them.We do not save that much time or $$$...but add to the confusion.
We do save space in the panel and on the neutral busbar!


They generally are permitted to serve only 120v line to neutral' loads,and commonly are choosen to serve 120v receptacle outlets ,permanently wired kitchen appliances ,split-wired duplex receptacle outlets ,and many other 120v loads, that occupy the same area.The kitchen receptacles may be every other one, on the opposite leg or 'split' between the upper and lower after removing the receptacle conductive tab...on the 'HOT' side only.


Many 'split-wired' 120v receptacle outlets, where one half of the duplex is on one circuit and the remaining half is on another,will many times, be supplied with a multiwired circuit.Both of these are on the same yoke.
It is my understanding that the Canadian electrical code, requires all duplex receptacles serving the kitchen counter, to be 'split ',and also are limited to 15amps.


The 3 wire service to your house is sort of like a multi wire circuit ,that also serves 240v loads,but this is not exactly the same!


Many electricians are suspicious of 3 wire , multi-wire ,shared neutral circuits ,because when it works as designed, all is well,but its tolerance for failure is usually catastrophic,when the neutral opens and places voltages in excess of 120v across certain random 120v loads…including electronic stuff.
It can also result in popping light bulbs!

For this reason….Always terminate the mutlwire white neutral, to a receptacle in a chain,via a pigtail jumper.
Don’t use the receptacle two silver screws as a tie point...unless the receptacle is the end-of-run.



The circuit MUST be supplied by the two opposing legs (lines) of the 120v/240v (120/208v)service.This is usually accomplished by feeding via a full size 2 pole breaker ,2 pole GFCI breaker,or a set of ADJACENT single pole, full size breakers ,which may be code required to be tied together,[handles secured together], so as to open both legs at once,especially if this multi-wire circuit supplys a "Split-Wired" receptacle,or device, on a single yoke.


Two adjacent half size or tandem/twin/duplex/piggyback/halfsize/wafer, breakers can not be used ,as they feed from the very same single leg,and if the multi wire circuit were fed this way, the neutral would very likely OVERHEAT and become a safety issue!!!
Remember ,by definition,the multiwire circuit is fed from two opposing legs and will have a voltage difference between them;240 volts in most residential ;208v in others.


Close attention must be exercised,as to how the circuit splits off, when it reaches any GFCI receptacle(s) ,and the neutral can no longer be 'shared'.


The neutral must never be allowed to open ,'upstream',along any part of the circuit,as it would place many of the 120v loads downstream,in series with one another and the full 240volts across these various sets ,and proceed to damage each 120v load in turn, over a short period,until none are left to destroy!

This is why the receptacle device, neutral connection, MUST always be via 'pigtails',and not the 2 silver-nickel screws on the side of the receptacle...or backstabbed.....unless of course the outlet is at the end of the run.


Multi wire branch circuits that are fed from a configuration, that by design or over-sight,does not simultaneously open and disconnect all legs of the circuit ,can really surprize an unsuspecting DIY or experienced electrician, that is working in a device or splice box,thinking that they have the circuit 'off' when in fact ,they do not!
Remember there is 240v or 208v in that box!


Two wire circuits are confusing to many,but three wire multiwire circuits,must be fully understood , and we must be absolutely aware of its advantages and also any consequences!


1999 NEC ref:....art 100 def:Branch Circuit,Multiwire
Section 210-4
Section 225-33.b Section 240-20.b.1 Section 300-13.b

FPN: Neutrals in 3Ø 4 wire 208/120v WYE systems ,etc,found in commercial and industrial supplies serving non-linear loads,like lighting ballasts,computer power supplies, etc will have high 3rd order harmonic currents and may have to be oversized,to prevent OVERHEATING




RECAP:
A MULTIWIRE branch circuit is considered a single circuit….and by the code definition...is "...A branch circuit that consists of two or more ,ungrounded..[NOT NEUTRAL]..conductors that have a voltage between them ,and a grounded [NEUTRAL] conductor that has EQUAL voltage between it and each ungrounded [HOT] conductor of the circuit and that is connected to the neutral or grounded conductor of the system.

This translates to ..120v from the shared white neutral to EITHER the red or the black...and ..also you will have 240v between the red and the black.

This all saves a wire..3 instead of 4....
this also saves $$$ and install time...and is common in kitchen circuits and some other rooms.

We will still have two breakers involved...and they MUST be on opposite phases...generally on adjacent spaces.
Generally a 2pole breaker.
But we can use two SP breakers and….
Generally handle tied .
The full sized single pole breakers ,if used instead of a 2 pole breaker… MUST be handle tied, if the multiwire circuit supplies both halves of a split duplex receptacle on the same yoke-strap.
Generally it is a 2 pole breaker ..TWIN TANDEM BREAKERS WONT WORK!


,,,and is possible, due to current cancellation... because we do not double the amps in the neutral..4 times the heat..but will approach ZERO amps.

The red and black wires will have currents flowing through them that do not ADD in the neutral ,but will cancel.

This principle is used in many circuits..especially in the service drop to our homes...3 wire!!!...


...and also all 120v/240v sub panel feeds.3 wire plus ground.

..as mentioned ,the best [common] example in our homes is in the kitchen receptacle outlets,for the required two 20amp small appliance circuits....two circuits ran in a single NM cable sheath..that share the single common neutral.

Some schemes choose to split the receptacles..upper on the red ..lower on the black...

..other schemes will alternate receptacle duplex outlets.
Every-other one on the red and black


..or even the dishwasher/disposal feed..etc


Read all the caveats ,..because they are touchy,even when installed by professionals.


When replacing split wired eceptacles...If we fail to also remove the BREAK-OFF tab on the new receptacle, we may wind up tripping the breaker,when the two opposing lines of a multi wire circuit come together..in a large 240v ZAPPP!

Many split receptacles are supplied via a 3wire cable, that is a multi wire circuit.240v between the red and black.

Not all 3 wire cables in switched receptacle boxes indicate a mutiwire circuit,as it may only involve just the switch loop...and half of the receptacle is hot, while the lower half is switched.

THE PRIMARY DIFFERENCE IN GFCI TYPE BREAKERS AND GFCI TYPE RECEPTACLES..IS SIMPLY THAT THE BREAKER IS 'LOOKING' AT THE ENTIRE CIRCUIT..AND..WIRING.....THE RECEPTACLE IS CONCERNED ,ONLY WITH THE OUTLET ITSELF AND ANY APPLIANCE THAT IS PLUGGED INTO IT...AND.. ANY DOWNSTREAM OUTLETS AND WIRING THAT EXTENDS FROM THE ‘LOAD SIDE’ OF THE PARTICULAR GFCI RECEPTACLE.


...this lower sketch in the image,where a 'normal ' breaker is feeding two gfci receptacles..look real hard ..as we can use these two gfci receptacles to feed and protect 'SLIT WIRED' generic duplexes that have the 'tab'(s) broken off...

..just be certain to NOT share the neutral ..we need a separate 2 wire + grnd extension from the load side of each gfci receptacle!

..one gfci load side can feed the top half of the split...and the other gfci load side can feed the lower half of the same split receptacle ...


Also remove the 'tab' on the neutral side....!!! or it will not set up for you.




>>>>>>>>>>>>&g t;>>>>>>>>>>>> >>>>>>>>>>>>&g t;>>>>>>>>>>>> >>>>>>>>>>>>&g t;>>>>>>>>>>>> >>>>>>
Another Multiwire circuit 120and 240 from one duplex!
STRANGE NEMA 5/6-20R COMBI RECEPTACLE

Pass and Seymour..P/N 5890..[5290 if 15amp].
Available at Home Depot.

The NEC references this as a multiwire circuit in 210-4.c ex 2..and since we are on a single same yoke... must be supplied via either a 2 pole breaker, or 2 full size single breakers with handle tie to provide a common trip.
If supplied via two fuses then we must provide a 2 pole disconnect.

NEC 225-30, when discussing second buildings and the ONE branch or feeder restriction,considers this a SINGLE circuit.
BUT OUR REQUIRED DISCONNECT NOW, MUST BE AT MINIMUM, A 2 POLE SWITCH!

AND GFCI IS ALSO AN ISSUE IF WE ARE IN AN OUTBUILDING...WE WOULD HAVE TO FEED THIS VIA GFCI BREAKER IN THE UPSTREAM PANEL.

NEC 210-4 permits multiwire branch circuits to be considered as multiple circuits.



THIS COMBINATION RECEPTACLE, AND ALSO COMBINATIONS OF MULTIPLE RECEPTACLES ON THE SAME CIRCUIT WITH THIS ARE "CODE"..BUT NOT GENERALLY RECOMMENDED...UNLESS USED IN VERY RESTRICTED SITUATIONS LIKE FOR A WINDOW AIR CONDITIONER

Have your local AHJ rule whether they consider each receptacle on this single yoke... restricted to 80% or 50 % ...!!!
See fastened in place.

This would restrict any possible applications ,even more.!!!

MULTI WIRE CIRCUITS ARE CONFOUNDING ENOUGH, BEFORE WE ALSO TOSS IN THIS HYBRID.

http://www.ecmweb.com/ar/electric_multiwire_branch_circuits/

[kactuskid]

[bogie002]

First off, thanks for all the info kactuskid! I understand most of this and feel that I can reroute these wires and reconnect. I was afraid somebody had done something wrong. Your information shows otherwise. I am really not adding anything, just moving them around. You mentioned not understanding what I mean by current still being there when the breakers are turned off. This is my main concern.

I made a drawing. Hope you can make it out. As you see there is a 3 way wire coming from the box. The red wire feeds the #8 circuit which seems normal. As shown the black wire, feeding the #9 circuit first goes to a switch. Two black wires go into one side of the switch, one comeing from the breaker box, the other going to the rest of the circuit. Another wire conneted to the other side of the switch going to a vent fan.

What seems strange to me is if I turn the breakers off (8 and 9), and disconnect the wire shown in the drawing to be going on to the rest of the circuit. Using a circuit tester on this disconnected wire, I show current when touching the white and ground. I also show current when touching the black and ground. I do not however show current when touching the black and white. This is just a cheap circuit tester but the light on it is shining bright. Surely something is wrong?

[kactuskid]

Is that a junction box installed where the circuit splits off and feeds to the rest of the circuit? Are there any other cables comming into this Jbox besides the 3 conductor power cable in and the two 2 conductor cables going out?

If that's it, then I would suggest that the breaker that controls circuit #9 is not really open when when the breaker is open. What is the make of your main panel and of the breakers. Are they Federal Pacific or Zinsco breakers?

[bogie002]

Yes, that represents a junction box. There was originally an outlet there. Yes, these are all the wires leaving this box. The panel says Sylvania. Im not sure on the breakers. I took some pictures if it helps. The breakers in question are the first 2 full size breakers. It looks like I have several of these multi wire circuits. Would I find the make of the breakers if I removed them?

On that note, should I remove the #9 breaker and see if there is still current there?


.

[kactuskid]

They're probably sylvania breakers as well. So, to measure whether the breaker is actually allowing power to pass even when it's open you'll need to buy a multimeter or a neon light voltage tester that can measure up to 240 volts. You should buy both cause they'll prove beneficial on other projects. Open both the #9 and #8 breakers. Then measure from the screw on each of the breakers where the wire connects to the neutral/ground bus bar. If you read 120 volts or get a light then you still have power. This would indicate the breaker is faulty. If you don't read any power with the breakers open, then make sure that the hot wires of this 3 conductor cable actually does go to the #9 and #8 breakers and not some other breaker in the panel. You may not be opening the proper breaker to begin with. Just something else to look at.

As for the rest of these breakers. You need to identify all of the circuits that are multiwire type. Then they all need to be installed on double pole breakers. This is a huge safety factor so don't wait on this.

I also notice you have some tandem breakers, those are the skinny ones that have 2 breakers in a regular slot. Is this a multiwire circuit that's connected to these as well cause it looks like it but I can't tell cause can't see if this cable also has a neutral wire with it. If it is, then this is a real problem cause these two breakers are operating on the same phase since they're in the same slot. Multiwire circuits need to be on opposite phases and take up two full slots using the double pole breakers. You've got plenty of room left in the panel to fix this though.

Gotta ask, who in the heck wired up this panel, they didn't really know what the heck they were doing. Let me know what you find out.

One last thing, is this your main electrical panel or is this a sub panel off the main.

[bogie002]

Sorry to wait so long to reply. Things got a bit hectic around here. I broke down and called an electrician And Im not real secure with Washington's practices when it comes to wiring. I checked the panel with these breakers off and still had voltage at this box. The electrician was not at all surprised by all the multiwire ciruits nor the way they were done. He said that it was normal practice.

He did however find that there was a wire from yet another circuit tied into this box [B)] He really didnt have an explanation for this but said if we just disconnected it and capped it off all should be well.

Its been a couple of weeks and the house is still standing. I feel a little better about the situation but, I will be changing out those breakers once this project is done. I understand how this works and he even adgreed to how dangerous the situation could be.

Kactuskid, to answer a few of those questions.

Yes one of the multiwire circuits is on a tandem breaker. (On the to-do list)

This is a main panel... there is a sub panel coming of of it holding breakers for 3 or 4 220v circuits.

As far as who wired the house, looks to me like original work that would have been done back in the 80's. Go figure...

Thank you so much for sharing your knowledge and for so patiently explaining all this Kactuskid. Ive learned alot from this experience and hopefully can make this a safer situation.

Thanks

Bogie

[kactuskid]

Hey Bogie, glad to see you're back, I was wondering what the heck had happened to you.

I'm glad you hired an electrician, you had quite the mess there and it's good to get experianced eyes looking at it. When you said the electrican wasn't surprized and thought it normal practice on the multiwire circuits, You do mean he still thought what you had was wrong don't you, but that he's seen that type of mess before. I sure hope that's what you meant.

One matter you need to take care of right away though is that tandem breaker with the multiwire attached to it. This is a really dangerous situation. Since multiwire circuits are supposed to be 180 degrees out of phase, it's safe for them to share the same neutral wire. But if you have a multiwire circuit connected on a tandem breaker, these two circuits are not longer 180 degrees out of phase and this means you're placing a double duty load on the neutral wire, which means that this wire is gonna be heated up way more than it should be and can break down and even cause a fire. So please, change this breaker out and install a double pole breaker in it's place before you have problems you don't wanna have.

Since you don't have space beneath this breaker to install a double pole, you're gonna need to move breakers to the other side of the main buss bar, and you need to make sure that the multiwire breakers are stacked one on top of the other with a handle tie to keep it all safe.

So another wire was bringing power into your junction box. Disconnecting it was a good idea, but I would of wanted to know which breaker controlled the power to this wire. Just to make sure it wasn't a multiwire circuit.

What all did the electrician do for you besides disconnect the wire, did he move some of these breakers around and put handle ties between them?

So you understand now about how these buggers work and that you need to install new double pole breakers or at least handle ties between two breakers, I'm glad. And I'm glad you learned alot and are getting it all taken care of. Let us know if you need anything else and thanks for the feedback.

[HayZee518]

I made up a drawing of several two-pole breakers and a couple of single pole units with a snap on tie-bar.

[kactuskid]

Nice drawings Hazy, a picture sure says alot more than words. Thanks.