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What happens when you share 2 20 amp breakers with 1 neutral wire?
Wiki User
∙ 14y ago
if it is (1) a-phase and (1) b-phase then this is the common and preferred wiring method (balanced). if you have two circuits of the same phase sharing the neutral then it is wired wrong (imbalanced). gfci and afci breakers need there own neutrals too. as far as what happens two examples:
A: (balanced system) a-phase carrying 10 amps, b-phase carrying 10 amps, neutral carries 0 amps.
B: (imbalanced system) a-phase carrying 10 amps, a-phase carrying 10 amps. neutral carries 20 amps.
hope this helps. good luck
This is not strictly true. Most residential power is supplied in a single-phase 120/240 volt format and has nothing to do with multiple phases. A single phase transformer secondary winding is center-tapped to provide two segments, each of which is 120 volts to the center tap point, which is grounded. There are then 240 volts between the outside ends of the full secondary winding. If both breakers are fed from the same ungrounded end of the winding, all of the current would pass through only one half of the secondary winding, and hence, through the neutral as well. If two breakers were installed such that they were fed from remote ungrounded ends of the secondary winding, then the only current through the grounded center-tap neutral would be the imbalanced current of the two circuits.
Wiki User
∙ 14y 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.
Any problems with shared neutral for for 4 15 amp breakers each on dedicated circuits?
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.
How do you change one breaker on a 3 wire that feeds two regular circuit breakers to a single arc fault circuit breaker - or do you have to change both breakers to arc fault so each has a neutral?
You can't change the one breaker, but you can't use two separate arc fault breakers unless you separate the neutrals. However double pole arc fault breakers are made for this purpose and the common neutral would be O.K.
What happens if you wire a ground and neutral wire together in an outlet box?
If there is a GFCI in the circuit it will stop working correctly. They compare ground current to neutral current to detect a fault. It makes ground current equal to neutral current which is a fault condition.
Does the NESC have any regulations as to how many volts can be on utilities primary neutral wire?
I am trying to find out myself, having found odd harmonics coming thru the neutral wire with my breakers open...I've been trying to identify the source of a strange hum/vibration in my home. If you mean the NEC, they have no power over electrical utilities. Your in home neutral wire should be at ground potential so there should be 0 volts to ground.
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.
What happens if neutral and hot touch each other?
If a "hot" wire contacts the "neutral" or ground wire, electrical current flows to the ground.
Any problems with shared neutral for for 4 15 amp breakers each on dedicated circuits?
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.
How do you change one breaker on a 3 wire that feeds two regular circuit breakers to a single arc fault circuit breaker - or do you have to change both breakers to arc fault so each has a neutral?
You can't change the one breaker, but you can't use two separate arc fault breakers unless you separate the neutrals. However double pole arc fault breakers are made for this purpose and the common neutral would be O.K.
What happens when neutral is bonded to ground wire most especially to dry type transformers?
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What is a floating neutral wire?
a loose connection of a neutral wire
What happens if you wire a ground and neutral wire together in an outlet box?
If there is a GFCI in the circuit it will stop working correctly. They compare ground current to neutral current to detect a fault. It makes ground current equal to neutral current which is a fault condition.
Does the NESC have any regulations as to how many volts can be on utilities primary neutral wire?
I am trying to find out myself, having found odd harmonics coming thru the neutral wire with my breakers open...I've been trying to identify the source of a strange hum/vibration in my home. If you mean the NEC, they have no power over electrical utilities. Your in home neutral wire should be at ground potential so there should be 0 volts to ground.
What does an open neutral mean?
Typical home wiring will have one hot wire, one neutral wire, and one ground wire per circuit. An open neutral would indicate that the neutral wire, usually white wire, is broken.
Is the ridged wire neutral or hot?
If wired properly the ridged wire is the neutral.
What happens to appliances when the neutral wire is disconnected?
Of course the u can't use the appliances because no electricity is flowing
Which side of the White neutral wire do you connect the Black power wire?
The neutral wire and power wire are never connected together.
