Questions tagged [mwbc]

Use this tag for questions about Multi-Wire Branch Circuits, sometimes called "Edison circuits".

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Derating for wires in conduit

I'm wiring my workshop (standalone 200-amp service) and running wires in 1-1/4" PVC conduit under the slab from the breaker panel on one wall to another wall about 50 feet away. I have one 50-amp ...
JeffC's user avatar
  • 31
3 votes
1 answer
166 views

Can I wire a MWBC with GFCI's using separate neutral wires on the load terminals?

I want to wire the circuit shown in the attached image in my garage. I want to have two circuits, and they need to be GFCI protected due to being in the garage. I've read through a number of posts ...
Alex Norton's user avatar
0 votes
2 answers
69 views

Tesla model 3 6-20 charging from existing circuit

I have a 20amp double pole 240v breaker suppling power to my 120v dishwasher and garbage disposal. They share the same circuit. It’s 12-3 awg and I have a access to this circuit before it runs to my ...
Evcharger's user avatar
2 votes
2 answers
150 views

Radio transmitter nuisance tripping AFCIs

I've got a DC powered ham radio in a spare bedroom converted to an office, with a coax feedline running up to an antenna up in my attic near the ridge. About six months ago, I upgraded my feedline to ...
rsaxvc's user avatar
  • 121
0 votes
2 answers
75 views

MWBC old outlet to new 2 connection outlet usb Cand A

I am updating my outlets to leviton usb A and C outlets. The new outlets only have hot common and ground. My old outlet has a white, black and red. It appears to have its own breaker from the other ...
Chris's user avatar
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1 vote
3 answers
138 views

Why are MWBC's permitted by NEC, given the neutral can take up to 2x the rated current?

I'm familiar with MWBCs and how they're used, especially as a cost saving mechanism when running home-runs for nearby circuits (e.g. dishwasher + food disposal). What I don't understand is how these ...
peter's user avatar
  • 1,381
3 votes
1 answer
308 views

multi wire branch circuits with 12/3 cable for 6-20r and 5-20r receptacles on the same circuit in a workshop

I am planning on similar MWBC wiring in a new shop we are constructing (40x30 pole barn). I plan to use a double pole 20 amp GFCI breaker for each circuit in a 200 amp panel, and put at least one ...
Jason Shapiro's user avatar
2 votes
1 answer
91 views

MWBC and GE Spacesave dual-pole breaker spanning over different pole/phase

I have 3 multi-wire branch circuits. And two of the 3 set of MWBCs were each put on same phase. An oerloaded neutral has occurred on one MWBC. (It was actually the case of oxidation, not overload, ...
John Greene's user avatar
3 votes
2 answers
174 views

Existing same-phase multi-wired branch circuit

Bought a 1960s home with aluminum wiring. I noticed that I have two sets multiwire branch circuit? (also known as "multiwire circuit", "multiwire branch circuit", "shared ...
John Greene's user avatar
4 votes
2 answers
624 views

Can you cut the outlet-bridge clip and run a 2-phase MWBC to a single receptacle?

Many outlets have a bridge clip on each side of the receptacle. (I have seen these used for things like making one outlet switched on one side but always-on for the other.) Question: If you have a ...
KJ7LNW's user avatar
  • 1,045
15 votes
4 answers
4k views

I installed a new outlet and tripped the whole power panel... Does a 30 amp circuit need special outlets?

So... I tried swapping two outlets in my kitchen, and tripped the entire power panel! The old outlets were wired with FOUR wires: red, black, white, bare. I wired the new outlets using the same ...
steeveedee's user avatar
4 votes
4 answers
765 views

When did Handle Ties become mandatory for MWBC?

Original Question I was extending a circuit in my kitchen last week as part of a remodel and discovered something that had been under my nose the whole time I've lived here but I just paid enough ...
Chris O's user avatar
  • 6,684
3 votes
2 answers
396 views

Multiwire Branch Outlet GFCI/AFCI breaker need but no product

I have a multiwire branch circuit (MWBC) connecting my dishwasher and disposal that connects to a Cutler-Hammer (using Eaton breakers) panel. After a renovation, an inspector told me I need the ...
Mike's user avatar
  • 153
5 votes
2 answers
1k views

Sharing Neutrals - How To Correct?

I have a 12/3 NM cable landing on two separate 20 amp breakers sharing a neutral between the two. They are landing on a Dishwasher/Garbage Disposal outlet. I understand this is NOT to code since there ...
Richard's user avatar
  • 559
2 votes
3 answers
1k views

Is this MWBC setup allowed?

I'm continuing to fix the issue introduced by someone else (Why run the same phase twice to a series of outlet?). The other room they did has this setup: a 3-conductors cable brings the same phase ...
Jeffrey's user avatar
  • 2,021
2 votes
2 answers
319 views

Replacing single duplex outlet on MWBC with two of them in kitchen?

My kitchen has a single duplex outlet (so two devices can be plugged in) on a multiwire branch circuit. I'd like to tear that out, replace it with a larger box and install two GFCI duplex outlets. ...
Grant's user avatar
  • 5,639
0 votes
2 answers
99 views

Changing Tandem Breakers with Potential Unmarked MWBC

I have two adjacent 20A tandem breakers in my panel. I need to change one of the breakers on each tandem to 15A (in order to protect 14 gauge wires on the respective circuits). The possibility exists ...
Justin's user avatar
  • 41
7 votes
1 answer
737 views

House Wired Incorrectly? - MWBC [duplicate]

I am working on finishing my basement. In my basement there is 3 junction boxes fed by 12/3 wire. Each junction box feeds a single 12/2 line (White-White, Black-Black, Ground-Ground, Red-Nothing). My ...
Jeff's user avatar
  • 71
4 votes
4 answers
1k views

Is a 120V/208V MWBC good enough for 240V loads?

As detailed in a previous post, I was planning to use the dryer circuit in my condo as a MWBC. A 120V/20A outlet between one of the two hot conductors and neutral would power my small washer and dryer ...
MarcoD's user avatar
  • 435
2 votes
1 answer
212 views

Replacing receptacle & switch on a MWBC in kitchen

Background: The house was built in 1983. Previous owner(s) have been creative on some DIY projects around the house. The receptacle was wired half direct & half sideways. Problems: The switch on ...
CecilG's user avatar
  • 23
0 votes
3 answers
858 views

How can I safely utilize a dryer outlet to power 100V and 220V loads?

In my house there is a dryer outlet that, even though inconvenient to me (my dryer is 120V), I don't want to eliminate for house reselling reasons. As it was until now a 3 prong outlet, I have been ...
MarcoD's user avatar
  • 435
0 votes
1 answer
419 views

Shared neutral on two circuits using a single-pole tandem breaker

I just looked inside of my sub-panel for the first time, which has ten single-pole tandem breakers. They all have two black wires connected, except for one breaker, which has a black wire and a red ...
K. Don's user avatar
  • 407
5 votes
1 answer
496 views

MWBC with both circuits on the same bus -- any easy fixes?

While moving some wires around in my garage (to make space for attic storage), I discovered an electrical issue that might be concerning: In my garage there are two circuits delivered as a MWBC, but ...
ldoogy's user avatar
  • 153
4 votes
2 answers
1k views

Is this a bunch of wrong MWBCs?

I've just opened up my main panel with the plan of adding a new circuit, but have temporarily aborted that idea after squinting for a while, followed by getting worried. I put some pictures from more ...
Scott's user avatar
  • 73
2 votes
1 answer
662 views

Wiring for switched NEMA 6-20R and 5-20R in same box in garage

My goal is to have 20A receptacles in a particular spot in my garage dedicated to power tools (such as saws) whose motors can be configured for either 240V or 120V, with a switch as a handy second ...
Matt Thomas's user avatar
6 votes
2 answers
2k views

Look over father's plan to fix outdoor electrical circuit

So to begin with, I am not a DIY'er when it comes to electricity. I prefer to allow the professionals to handle these matters as it's not something I'm confident in and not too knowledgeable about... ...
Austin Stepp's user avatar
9 votes
3 answers
3k views

Splitting 240V into two 120V Circuits

I think I have this figured out for the most part but looking for validation from expert strangers on the internet. Renovated the kitchen in this 1960's house. I think it probably has been renovated ...
Tyler Herron's user avatar
2 votes
1 answer
431 views

GFCI breaker on a MWBC (Shared common)

We are doing kitchen reno. We had to replace the main breaker panel. Local code requires we use arc fault breakers. This is not an issue for most of the project, however, the inspector is insisting ...
user3442730's user avatar
1 vote
2 answers
936 views

GFCI receptacle connected to Multi-Wire Branch Circuit

I have a Multi-wire branch circuit & would like to connect GFCI receptacles. The MWBC currently powers dimmable LED lights in basement. In process of finishing basement. I would like to extend ...
jjcarey44's user avatar
1 vote
2 answers
233 views

Identifying what receptacles and fixtures are on each branch of a MWBC

How should I safely identify which breaker controls which fixtures & receptacles in a Multi-Wire Branch Circuit? There is intentionally a handle tie for the MWBC in my panel which must be kept to ...
Aaron's user avatar
  • 105
2 votes
3 answers
203 views

Disposal Circuit Update

I moved to a house built in 1995 and want to update the disposal connection, but found some conflicting rules that I don't know how best to comply with. The existing connection is a 14-2 NM cable run ...
Robert Chapin's user avatar
0 votes
2 answers
395 views

3 phase MWBC - 2 pole breaker with shared neutral

I’ve searched around and can’t quite find an answer to my question. I understand that you can share a neutral on a 3 phase panel if you use a 3 pole breaker. But can you still share a neutral on a 3 ...
Snah's user avatar
  • 1
4 votes
3 answers
657 views

MWBC exists, use for bathroom?

I am finishing my basement. The previous owner had ran a MWBC to the area that will be the bathroom. In the panel it is two 1-pole 20amp breakers. My questions are: First to confirm, it seems I ...
DaveS's user avatar
  • 43
2 votes
2 answers
515 views

MWBC for split kitchen receptacle

When installing a split receptacle in a kitchen, where the top and bottom are each their own circuit, is there any way you can use an MWBC, or is your only option to run two normal circuits with two ...
Joseph Sible-Reinstate Monica's user avatar
2 votes
2 answers
315 views

Can I have an MWBC plus another circuit in the same junction box?

The conduit coming in on the left carries a 15 A MWBC. In this junction box, it splits to the brown-to-black wire for the furnace, and the orange wires to some basement lights (top) and an upstairs ...
LShaver's user avatar
  • 1,296
4 votes
3 answers
5k views

Two Circuits on a Single 12/3 - Shared Neutral

I was recently trying to upgrade a 20A breaker supplying outlets in my kitchen and dining room to a CAFCI breaker. When I opened my breaker box I saw that the neutral on this circuit was shared with ...
Nigel Crawford's user avatar
5 votes
3 answers
753 views

Multi-Wire Branch Circuit on wrong breakers

My electrical panel has a double-pole breaker that looks like it's for a MWBC, but actually the attached wires are from different cables. In the below picture the black wire with the yellow rubber ...
IceGlasses's user avatar
5 votes
2 answers
2k views

In a multiwire branch circuit, can the two hots be connected to the same phase?

This may be an obvious question, but I haven't been able to find a direct answer. I believe I have a MWBC - I have two hot wires connected to two separate circuit breakers, sharing a neutral and ...
Mwinn's user avatar
  • 51
2 votes
2 answers
346 views

Is this a weird or very problematic shared neutral?

I will try to explain it and I made a drawing that give an idea of what it seems to look like. I just had some work done on my house (built in 1967) and the electrician found this weird connection. I ...
Fredou's user avatar
  • 175
8 votes
3 answers
1k views

Neutral pigtails on MWBC

I've recently moved into a new home with a few outbuildings. Due to the property being in rural unincorporated area, no inspections or permitting was required on the outbuildings when they were built ...
cyclops's user avatar
  • 857
2 votes
1 answer
871 views

2 independent GFCI (or 2-pole GFCI) outlet in 1-gang box. Does that exist?

I have a 1-gang duplex outlet under the sink in my kitchen. The two outlets are on separate phases of a single MWBC circuit. One of them powers the garbage disposal, and is controlled by a switch. The ...
Haozhun's user avatar
  • 263
3 votes
2 answers
2k views

Is it possible to wire 2 GFCI receptacles on 2 circuits with 12/3 wire shared neutral?

I am planning to run a few needed 20amp outdoor receptacles (and therefore want GFCI). My plan was to run 12/3 wire from 2 separate circuits in the panel to a double gang weatherproof box with 2 gfci ...
silversurfer's user avatar
3 votes
1 answer
126 views

MWBC and very low power factors

The principle of an MWBC is that two hots can share a neutral if they're on opposite phases, since the current on the neutral will cancel instead of adding. But isn't this only true for loads with ...
Joseph Sible-Reinstate Monica's user avatar
0 votes
1 answer
437 views

Diagnosing a suspected multi wire branch circuit

Last week I lost power to my new garbage disposal. I opened the box to find this: There are three cables coming in from the bottom. Two of these are somewhere downstream from the Panel, not too sure. ...
Josh Sharkey's user avatar
0 votes
2 answers
246 views

Convert MWBC to single 240V receptacle

I currently have a 20 amp double pole breaker supplying a multi-wire branch circuit for two 120v receptacles in a double gang box. I'd like to remove the 120v receptacles and install a 240v receptacle....
David's user avatar
  • 1
1 vote
1 answer
195 views

Is this a MWBC?

I think I have some MWBCs that are not handle tied. Can you tell from this picture if the bottom red breakers and top blue breakers are MWBCs? I can't trace back to the conduit and they supply "...
Matt P's user avatar
  • 11
2 votes
1 answer
120 views

Can I serve mwbc 110v from 220v circuit?

If I have a 240v 20a circuit serving a single 240v 20a receptacle (12/3) can I leave the 240v receptacle in service then branch two 120v 20a circuits from it?
Matthew's user avatar
  • 9,423
5 votes
3 answers
972 views

Shop Electrical - MWBC Serving 240V and 120V Outlets

I've seen this setup in use in other shops and am interested in using the technique myself. However, the mere mention of it seems to incite rabid pandemonium rather than civil discourse. I'd very ...
Paul Fitzgerald's user avatar
1 vote
2 answers
281 views

Overloaded circuit on ungrounded outlets

So I've stumped/annoyed most of the internet with this one. I hope there might be someone who can point me in a different direction.. I have a house built in 55 with ungrounded outlets. A space ...
kmp's user avatar
  • 11
1 vote
2 answers
2k views

Connecting 120/240 receptacles on the same circuit breaker

I want to add a branch circuit to the control panel using 12/3 wire and protected by 20 amp double pole circuit breaker. Is it safe to connect multiple duplex receptacles 120 volts and 240 volts on ...
Ehab Teima's user avatar