A lot of lights and appliances in a traditional home run on 120-volt electricity, but a few of them consume too much power for that and are should be supplied with 240-volt electricity. Examples of these include water heaters, dryers, and furnaces. Every single 240-volt appliance should be on its dedicated circuit that is controlled using a breaker that is rated for the current specifications for that particular appliance which is specified on its attached label. A room air conditioner is a good example of the appliance that will need a 30-amp breaker.
The breakers that can control 240-volt circuits is known as the double pole breaker. Each one is made up of two separate breakers which are permanently connected together. One breaker contacts one of the two 120-volt hot buses within the panel and the other breaker contacts the other hot bus. When you join the wire to one of the breakers and the other hot wire to the second breaker, the voltage that is generated by both wires is 240 volts.
A double-pole breaker is not a tandem breaker
There is a certain confusion that can be seen between a double –pole breaker and a tandem breaker, which also is made up of two breakers that are connected together. The difference that exists between the two is that a tandem breaker such as the QO tandem that is manufactured by Square D which is a leading manufacturer of breakers and panels is, in fact, a pair of a single-pole breaker. It is designed in such a way to occupy a single slot panel and can act as double independent 120-volt breakers. A tandem breaker offers a way to get more operations from a panel that is almost full. Tandem breakers are normally rated to handle 15 or 20 amps, which is the number that is marked on the front. When it comes to double-pole breakers these are normally rated to handle less than 30 amps.
The basics of a 240-volt wiring
Electricity normally enters the panel using a pair of hot wires having a voltage of 240 volts where each holds 120 volts. Each of the two wires is connected to a bus bar, and 120-volt circuits take power from one or the other among these bus bars, and this means a 120-volt circuit breaker is designed to connect a single bar. The bars are forged in an S-shape making the successive breakers contact each one alternately. 240-volt breakers take two slots within the panel by contacting both bus bars.
A 240-volt circuit requires a 3 – conductor cable which has a minimum wire gauge of 10 AWG. The cable consists of two hot wires, which are colored black and red, and contain a neutral and ground wire which is not considered as a conductor. Every single hot wire is joined to one of the two terminals upon the double-pole breaker, whereas the neutral wire gets connected to the neutral bus in the panel as the ground wire is connected to the ground bus.
Connecting a 30-amp double pole breaker
The circuit breakers are not interchangeable as they cannot be installed from one different panel model to another. Make sure that when you purchase a breaker you have to get one from the same company that manufactured your existing panel.
The cable that is powering the circuit has to be securely clamped in order to access the port. After stripping an inch of insulation from each of the wire in the cable, connect the white wire to an available plug upon the neutral bus within the panel and then connect the ground wire to a ground bus. Besides, connect the red wire to the lug on one of the breaker terminals and this does not matter as whatever wire you connect will not have any problem. Then connect the black wire to the other terminal. The breaker usually snaps or hooks within a chosen slot. Not that you will need two adjacent slots to connect them to a double pole breaker. Once the breaker is installed in place and you have turned it on, the circuit is already energized.
Working in the panel is so dangerous as the hot bus bars are normally energized. Due to this danger, it is better that you let a professional licensed electrician do the work.