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Any problems with shared neutral for for 4 15 amp breakers each on dedicated circuits?
Wiki User
∙ 9y ago
Yes. If it a residential home then you can only have two breakers per neutral and they need to be on opposite legs of your panel. If it is a commercial 3phase panel then you can only put 3 breakers on a shared neutral. Here's why. In your panel assuming its residential you have two power wires and one neutral and these power wires are called legs. If you attach two breakers on the same leg that is across from each other on opposite sides of the panel or skipping a space between breakers on the same side at 15A apiece you return on the neutral will not be balanced and you will have the possibility of 30A coming back to your panel on the neutral which will fry a 14 Awg or even 12 Awg for that matter and cause a fire. Now if the breakers are in tandem that is they have the breaker tie that connects two breakers together they will be on separate legs and then only will your breakers/circuits be balanced and it will be safe to share a neutral on. If two tandem breakers are connected to a single neutral and they are all 15A breakers your return would be 30A again because although your tandem breakers are balanced now you have two tandem breakers returning a potential 15A per two breakers and that adds up to 30A. The next problem you have is when you share a neutral as per the National Electric Code if one breaker trips the other breaker also sharing that neutral must trip so that when the power is off any current that could possibly return through the neutral wire will be cut off. So now this creates another problem with 4 breakers sharing the same neutral is now there is no way to get all four to trip at the same time if there was a ground fault (a short) or an overload. and someone could get nailed by any current coming back on the shared neutral. All the same applies for 3phase except there are 3 power wires and you can use 3 breakers with a 3 breaker tie instead of just two. You either need to run one neutral per tandem breaker or four neutrals for four circuits/breakers. Tandem breakers controlling two separate circuits are a pain because when one breaker trips they trip the other circuit also. Tandems are mostly used for two circuits going to the same appliance so that no power on either leg reaches the appliance when it needs to be off.
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∙ 9y ago
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What is an electric shared neutral?
An electric shared neutral is the white or negative wire that is shared between two electrical circuits on a basic single phase system. Most electrical devices use 120 volts and require a "hot" wire and a neutral wire to operate. Some larger devices use 240 volts and require two "hot" wires to operate. Two circuit breakers in an electrical panel can share one neutral wire as long as the breakers are not on the same "leg" of power. When looking at an electrical panel there are usually two "legs" of power feeding all the breakers, each leg has 120 Volts to ground, if the "legs" are combined you will have 240 Volts. A neutral wire can be shared by two circuits as long as the breakers are on separate "legs". If someone needed to add two circuits in their home, the could run what is called a 3-wire romex, It has a black wire, a red wire, a white wire and a ground wire. The white wire is the neutral for both the black and red 120 volt circuits, and the breakers for the new circuits would need to be on separate "legs" in the panel.
Do you have to pin breakers together when sharing the neutral on branch circuits?
Pinning breakers is becoming a thing of the past. This is due to the manufacturing of two pole breakers with one common trip reset handle. The electrical code states that on a 240 volt breaker if one leg trips the other leg must be disconnected from the supply also. This is a safety factor so that if they weren't tied together and one leg tripped the other half of the breaker would remain "hot". Any one working on that circuit in the tripped position could get a nasty shock from the un-tripped leg. Pinning the breakers on 240 volts was done because it was convenient to use single pole breakers in the distribution panel. To abide by the code the two single pole breakers were common tied together. When the branch circuits share a neutral to a common box they have to be common tied for the same reason above. This type of circuit is found on kitchen counter receptacles. Two separate circuits that share a neutral and go to separate junction boxes do not need the breakers tied.
Do you need arc fault breakers if you put in a new panel in a old house?
If your jurisdiction is using a version of the NEC that requires arc fault breakers, then yes. Call your local building and planning department to see what revision of the code they are using. The exception to this is that you cannot use arc fault breakers if the circuits in question are wired as multiwire circuits (two or more individual circuits sharing a common neutral) because the arc fault breaker won't work in that arrangement. You're not required to replace the entire electrical system just to change a load center, so in this circumstance you wouldn't need them. If you're using the 2005 NEC, you only need arc fault breakers in the bedrooms. If you're using the 2008 NEC, you'll need them just about everywhere that isn't covered by ground fault breakers.
Do you need dedicated neutral for 50hertz 220volt?
Yes
Can 12 2 w gnd wire be used for two different 20 amp circuits safely meaning I would have two separate circuits on two separate 20 amp breakers There would only be 1 white wire returning?
Yes, you can do this, but there are a few rules to follow. The white wire(neutral) should be solidly made at all device boxes in other words do not use the receptacle terminals, make all the joints solid and pigtail to the receptacle. The breakers need to be adjacent to each other in the panel, side by side on opposite buss bars. If you put them on the same buss you will overload the neutral. Use a handle tie on the breakers.I am sorry. It was the wrong question. The question really should have been: Can you wire two separate 20 amp circuits using one single romex 12-3 w/ground. Each circuit would have it's own 20 amp breaker. The Red wire would be landed on one breaker. The Black wire would be landed on another breaker. Only one #12 white wire would be available for neutral. My theory is: If you were to load both circuits to say 19 amps each, you would have 38 amps being used. The problem lies in the single white neutral's ability to handle 38 amps on it's own. Wouldn't this be a problem? Would this configuration pass in spection? You can do this with 12/3, you still have to make up your neutrals at device boxes. the neutral would not have to handle 38 amps as long as you use opposite 110volt buss. the current on the neutral if both breakers were drawing 16 amps each would be "0". The neutral only has to carry the imbalance of the two circuits. If one breaker draws 16 amps and the other 8 the current on the neutral would be 8 amps. Breakers have to be on opposite buss! for this to work. Yes, it should pass inspection.
What is an electric shared neutral?
An electric shared neutral is the white or negative wire that is shared between two electrical circuits on a basic single phase system. Most electrical devices use 120 volts and require a "hot" wire and a neutral wire to operate. Some larger devices use 240 volts and require two "hot" wires to operate. Two circuit breakers in an electrical panel can share one neutral wire as long as the breakers are not on the same "leg" of power. When looking at an electrical panel there are usually two "legs" of power feeding all the breakers, each leg has 120 Volts to ground, if the "legs" are combined you will have 240 Volts. A neutral wire can be shared by two circuits as long as the breakers are on separate "legs". If someone needed to add two circuits in their home, the could run what is called a 3-wire romex, It has a black wire, a red wire, a white wire and a ground wire. The white wire is the neutral for both the black and red 120 volt circuits, and the breakers for the new circuits would need to be on separate "legs" in the panel.
Do you have to pin breakers together when sharing the neutral on branch circuits?
Pinning breakers is becoming a thing of the past. This is due to the manufacturing of two pole breakers with one common trip reset handle. The electrical code states that on a 240 volt breaker if one leg trips the other leg must be disconnected from the supply also. This is a safety factor so that if they weren't tied together and one leg tripped the other half of the breaker would remain "hot". Any one working on that circuit in the tripped position could get a nasty shock from the un-tripped leg. Pinning the breakers on 240 volts was done because it was convenient to use single pole breakers in the distribution panel. To abide by the code the two single pole breakers were common tied together. When the branch circuits share a neutral to a common box they have to be common tied for the same reason above. This type of circuit is found on kitchen counter receptacles. Two separate circuits that share a neutral and go to separate junction boxes do not need the breakers tied.
Can you use a GFCI on an unswitched circuit line red that uses the same neutral white for a switched circuit coming from the other phase line black in a 240v breaker panel?
Yes. You are allowed to use a neutral for one circuit from each phase of your service. For example, in a residential service, you can use the same neutral for circuits 1 and 3. In a commercial (3 phase) service, you can use a neutral for circuits 1, 3, and 5. You will experience problems if you use a neutral for two 'black' circuits or two 'red' circuits, if the circuits originate from the same phase bus bar. Also, AFCI's are sensitive to sharing neutrals, but GFCI's are not.
If you are making your own device and you bring in 208 3 phase for part of your needs - how can you properly tap 110 single phase from it to operate other parts of your device?
Your incoming 208V 3 phase power supply will also need an incoming neutral of the same conductor size. Then any single pole breaker installed in the panel will have 110 volts to the neutral. That is you can run 208V 3 phase motor circuits from a three phase breakers in the panel and any number of 110V circuits from single pole breakers.
What is the code ruling in the US on 3 phase branch circuits and the neutral?
A three phase system will have 3 phase branch circuits and no neutral.
What is meant by tp and tpn circuit breakers?
The difference of TP and TPN in circuit breakers is the ability of the switch to hold a neutral position. With TPN, a neutral switch position is not possible. With TP, the breaker can be held in a neutral position.
Do you need arc fault breakers if you put in a new panel in a old house?
If your jurisdiction is using a version of the NEC that requires arc fault breakers, then yes. Call your local building and planning department to see what revision of the code they are using. The exception to this is that you cannot use arc fault breakers if the circuits in question are wired as multiwire circuits (two or more individual circuits sharing a common neutral) because the arc fault breaker won't work in that arrangement. You're not required to replace the entire electrical system just to change a load center, so in this circumstance you wouldn't need them. If you're using the 2005 NEC, you only need arc fault breakers in the bedrooms. If you're using the 2008 NEC, you'll need them just about everywhere that isn't covered by ground fault breakers.
Why neutral is not required for vacuum circuit breaker?
Air-blast circuit breakers are used to disconnect high-voltage transmission or distribution circuits in the event of a fault. One circuit breaker is required for each of the three line conductors; there is not normally a neutral conductor in high-voltage three-phase transmission/distribution lines.
Do you need dedicated neutral for 50hertz 220volt?
Yes
Can a dedicated circuit share a neutral?
It depends on:what you are calling a dedicated circuitWhether there is ANY possibility that the neutral could be required to carry a load in excess of the rating of the wire.First we have to make certain that we're talking the same language, second we have to consider the fire hazard involved. (although, if we're looking at safety, we would need to reverse the two)The simple answer is No.The term "dedicated circuit" is not defined in the code. But in practice the term refers to a circuit that is run for a particular purpose, often to one piece of equipment or receptacle (outlet). Sharing a neutral contradicts the principle of a dedicated circuit.Sharing a neutral would expose the circuit to electrical elements such as harmonics. A dedicated circuit is intended to avoid such problems.
Why does the neutral in power circuits run hotter than the active?
Neutral must be carrying a leakage or fault current continuously
Can 12 2 w gnd wire be used for two different 20 amp circuits safely meaning I would have two separate circuits on two separate 20 amp breakers There would only be 1 white wire returning?
Yes, you can do this, but there are a few rules to follow. The white wire(neutral) should be solidly made at all device boxes in other words do not use the receptacle terminals, make all the joints solid and pigtail to the receptacle. The breakers need to be adjacent to each other in the panel, side by side on opposite buss bars. If you put them on the same buss you will overload the neutral. Use a handle tie on the breakers.I am sorry. It was the wrong question. The question really should have been: Can you wire two separate 20 amp circuits using one single romex 12-3 w/ground. Each circuit would have it's own 20 amp breaker. The Red wire would be landed on one breaker. The Black wire would be landed on another breaker. Only one #12 white wire would be available for neutral. My theory is: If you were to load both circuits to say 19 amps each, you would have 38 amps being used. The problem lies in the single white neutral's ability to handle 38 amps on it's own. Wouldn't this be a problem? Would this configuration pass in spection? You can do this with 12/3, you still have to make up your neutrals at device boxes. the neutral would not have to handle 38 amps as long as you use opposite 110volt buss. the current on the neutral if both breakers were drawing 16 amps each would be "0". The neutral only has to carry the imbalance of the two circuits. If one breaker draws 16 amps and the other 8 the current on the neutral would be 8 amps. Breakers have to be on opposite buss! for this to work. Yes, it should pass inspection.
