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49

It starts with spaces in the panel A service panel has a basic unit I call a space. That's apparent when you look at the "knockouts" on the cover. Electrical power in North America delivers split-phase power. Meaning there are two "legs" or "poles" - L1 and L2 - both 120V from neutral, and opposite-phased so they add up to 240V. Here's an X-ray of a ...


10

A shared-neutral (two hots sharing the same neutral) is also called a multi-wire branch circuit (MWBC). Now to go any further, first, North American power uses a slick trick. It supplies 120V in two poles, which can be stacked to be 240V. Read this answer for a primer on how that works. Then, read my answer on how poles work at the panel, and what makes ...


10

Multiwire branch circuits (MWBCs) share a neutral. There is a code rule that prohibits wiring devices, such as receptacles, in a way that the removing the device would open (i. e., disconnect) that shared neutral. If the device is pigtailed, that rule is satisfied because removing the device doesn't disconnect anything else on the circuit from the neutral. ...


7

Close, but not quite. From the point of the two GFCIs onward, the neutrals must be kept separate. Consider: if you had a device drawing power on the black hot circuit from a load farther down the line, and nothing on the red, which GFCI would its neutral return current flow through? Since they're just connected in parallel in your diagram, it would flow ...


7

No, you really need to fix that. Search this site for "Lost Neutral" for what happens when the neutral wire has a problem. It's bad, and it can set stuff on fire. Look at that neutral in your photo. Simply to transit this box, current must go through four splices. Two on each receptacle - supply, jumper, jumper and onward. That's 4 places for ...


6

The electrician is right. The circuit is improperly sized for these loads. It's very likely that the microwave was added as an afterthought without a moment of consideration for circuit loads. This is typical of work done by homeowners or appliance installers. The reason is simple enough: installing a new circuit is way beyond the license of the ...


5

Whoever told you that was referring to ***A***FCI breakers, and only in the context of a GE panel. In every other case, they don't know what they're talking about. A GFCI operates by comparing the currents on all the normal/intended conductors to assure that current in = current out To do that, it needs access to all the conductors at once (not ground)....


5

Never gonna work. Sorry, but even if you might be able to get one at a time to work, GFCI on MWBC is based on the breaker comparing "all hot" to "all neutral". Two electrically separate breakers simply can't do that. The handle tie requirement satisfies the general MWBC safety issue of making sure that if one is off for maintenance then the other is off as ...


5

That drawing cannot possibly work. Right off the bat, you are paralleling, providing two paths for neutral to go. That itself is a code violation, nevermind the GFCIs. It won't work because as Nate Strickland describes, neutral won't know which path to take. GFCIs involve looping all the wires of a circuit through a current transformer, where each wire ...


5

This is fine, provided you obey a few rules While a MWBC serving a mix of 120V and 240V receptacles certainly may look strange to the uninitiated, or those who interact with electrical systems in a professional capacity yet are not trained to the full panoply of NEC requirements, this setup is Code-legal in the 2017 NEC, provided the breaker protecting it ...


4

This is no good What's happening right now is that the bare grounding wire in the 10/3 feeder cable is being abused as a neutral by someone who clearly didn't know any better (as no-grounding-conductor feeders have not been Code for new installs for a while now). You're going to need to re-terminate the cable (and probably use a box to splice some extra ...


4

The 2-pole 20A breaker is correct for an MWBC. The only difference between a 2-pole breaker and two 1-poles handle-tied is that the 2-pole breaker guarantees common trip, and the handle tie does not. Yes, a 2-pole breaker will let you flow 18A on one leg and 19A on the other. The breaker has no connection to neutral and does not know or care what ...


4

No. Find any other partner device. Microwave + garbage disposal, fine. Microwave+dishwasher, fine. Microwave + 1 of 2 kitchen receptacle circuits, fine. Nothing shares a circuit with a refrigerator. Because food spoilage is serious business. You really don't want a situation where someone comes into the kitchen, looks at the time, the microwave is ...


4

This will work as long as the breakers are not GFCI. As long as the GFCIs are after the shared neutral, you are fine. BTW, this arrangement is called a multi wire branch circuit and you are required to use either a double (240 volt) breaker or two breakers with the handles tied together.


4

The problem is not a fire it is a shock hazard. As far as if it is important, it has been code for decades. The issue comes when the neutral may get separated then everything down from there won’t work, but there are still 2 hot legs with GFCI protection. The risk is low but it should be updated. A wirenut and pigtails to the receptacles really won’t take ...


3

Your understanding is correct EXCEPT you cannot put a 15A or 20A receptacle on a 30A breaker. The 30A circuit must be wired to an outlet that is designed for 30A. This would be a NEMA 6-30 if you don't need the neutral, or a NEMA 14-30 if you do (or the NEMA L-series locking equivalents). There are devices factory-wired for these plug types in America. ...


3

You do not have a "120V MWBC". You have a plain MWBC. 240V-only (no neutral) loads are allowed on MWBCs. They even make receptacles for that. Note how there is no tab to break away on the visible side, since one must be neutral and the other L2. However you can see the tab peeking out from the other side, which could both be L1 of the same circuit.. ...


3

First, congratulations. This is the most well-thought-through presentation of a plan that ai have ever seen on this forum, and your thoroughness has paid off - you got everything right, including an ambitious use of a MWBC, with all its details right. By your first paragraph I was thinking "MWBC" and voilà you're already there. Well done. The breaker ...


3

According to 210.4.c of the NEC MWB shall supply only line to neutral loads. With 2 exceptions. #1 supplies only 1 utilization equipment. #2. All ungrounded conductors opened are opened simultaneously by the branch circuit OCD. Because of this wording many inspectors won't allow line to line to be used but it is legal , if you have a NEC hand book you can ...


3

Land all your MWBCs on a 2-pole breakers NOW. First, big safety problem. If an MWBC has both its legs on the same pole, it will overload the neutral. It's important to search your entire panel for multi-wire branch circuits and replace all their breakers with 2-pole breakers. Not two adjacent breakers. A 2-pole breaker specifically. Why? GE Qline ...


3

I'm thinking of driving a grounding electrode at the garage and connecting the equipment grounding conductors of the branches in the garage to that electrode, which wouldn't be bonded to the neutral. This doesn't work. Let's say you have a piece of equipment short the hot wire to the ground. The power tries to get back to the source. When it tries on your ...


3

The bare ground + triplex is a reasonable solution, assuming we're talking type USE triplex here Underground direct bury multiplex cables, such as the USE triplex your power company is trying to sell you on, have all their conductors (hots + neutral) insulated. This means that you can use it along with the separate ground wire in the same trench, as per ...


3

Cap the neutral off and you’re done. However, since your breaker is 2-pole with common trip, you’re perfectly allowed to eat your cake and have it too. You can replace one side’s receptacle with either a dual NEMA 6-15 a dual or single NEMA 6-20, or a combo NEMA 5-20 NEMA 6-20, giving one socket of each. Come off the hot of the other receptacle to the 2nd ...


3

Code requires 2 things: First that all junction boxes be accessible, and second that wire splices happen only inside junction boxes. That is why everyone is expecting this should be accessible. So there are 2 big problems. First that breaker's handle-tie is completely hork-a-dork (credit for having a handle-tie, but they should've gotten a proper one). ...


2

This needs to be addressed now, not at some hypothetical future when you acquire a Round Tuit. Change the 3-way switches to any of a variety of smart switches that require only one traveler. The master goes near the light. Now the wires return to their proper function: ground is ground white is neutral black is always hot red is 3way comms If you ...


2

It looks really good. Few things. The house is a subpanel because the neutral-ground bond is not there. This is a common setup, though usually not with such distance between the separate main breaker and the "main" subpanel. The 100A breaker in the "main" subpanel in the house is meaningless. Its only purpose is to be a shutoff switch. As such, its ...


2

The lowdown is panels are sometimes better compact and squeezed down for minimal space saving features. To achieve this, panel manufacturers use what is called tandem breakers. Most panels have a maximum allocation for tandem breakers and is abbreviated with a ratio. For example 12/24 ( 12 space / 24 circuits ).


2

Change the main panel breaker to fit the wire run Start by finding out what size of wire this is. Now the main panel breaker size needs to be changed to match the wire. The job of that breaker is to protect the wire, and the electrical cabinet downstream. #6 wire is good for 60A #8 wire is good for 40A #10 wire is good for 30A #12 wire is good for 20A ...


2

You can do this and I used to do it more often. Common trip or 2 handle tied breakers a trip will probably trip them both but I don’t see this as a big deal. how many use their microwave for more than an hour? Most microwave usage you are right there and if not will be at the end of the cycle so if the microwave trips it’s circuit it’s not like something ...


2

What you're talking about is a Multi-Wire Branch Circuit. There are two problems with you trying to take one of these on. They are effectively obsolete, as GFCIs and AFCIs are now required on the vast majority of 120V circuits, and MWBCs do not play well with GFCIs and AFCIs. They are for wizards only: You need to know many more things to do an MWBC ...


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