Parallel circuits with the same voltage series circuits with voltage division All of the connections in a household are in parallel since all of the elements (fan, bulb, refrigerator, AC, TV, oven, etc.) get the same voltage yet draw different currents than what is required. An AC, for example, consumes far more electricity than a fan, light bulb, or refrigerator. Yet, it is only using **a small portion** of the total voltage being supplied by the power line to the building.

In electronics, a parallel circuit is a collection of devices that connect together in **one group** or layer. In an electrical circuit, parallel connection means that two or more wires, lines, or paths carry equal amounts of current. The current carried by each wire or path cannot be controlled separately but rather must be equal. If one branch of the circuit carries more current than another branch, then they are not parallel and should not have the same potential. A series circuit is a collection of devices where only one device receives voltage while the others simply pass **this voltage** on without any additional load. Groups of LEDs connected in parallel require less current to light up than if they were connected in series because the individual diodes can share the load.

In mathematics, logic, and computer science, series and parallel are terms used to describe sets of components or circuits that function differently.

- Is the parallel circuit the same as the series circuit?
- How are series and parallel circuits similar and different in how they transfer energy?
- How are series and parallel circuits used in HVAC?
- How are branch currents related in a parallel circuit?
- What are the patterns for voltage and current in a parallel circuit?

Series and parallel circuits are built with the same current flowing through each component, whereas series and parallel circuits are constructed with the same voltage flowing through each component. The only difference between these two types of circuits is where the components are connected together.

In a series circuit, the output signal or power is the same at all the components. If one component breaks, then all the other components also break because the current cannot turn off at any single point. In parallel circuits, however, if one component fails then it can be replaced without affecting the rest of the equipment. The current can still flow through **the remaining parts** of the circuit so long as the voltage is still there.

Energy will be transferred in **both series** and parallel circuits but only series circuits need to be considered when calculating **power supplies** or large circuits since they cannot function properly if even one component fails. Also, note that batteries used as energy sources in circuits should never be connected in series due to the risk of complete discharge if one cell gets too low on charge. Cells should be separated from each other so that if one cell discharges completely another can take **its place** so that the battery always has some capacity left when needed.

The connection of components in circuits determines how energy will be transferred.

A series-parallel circuit is a hybrid of a series and a parallel circuit. These circuits are used in heating, air conditioning, and refrigeration equipment to connect **control circuits** with circuits that deliver line power to loads. The term "series-parallel" comes from the fact that these circuits contain components that connect together in a series arrangement at one end and in a parallel connection at the other end. For example, a three-wire system could be designed so that all the heaters were connected in a series circuit at one end and a single thermostat controlled them all from **one switch** at the other end. This would be a series-parallel circuit.

Heating, ventilation, and air-conditioning (HVAC) systems use series-parallel circuits to connect controls and terminals together that receive electricity from a central power source and distribute it to various outlets for lights, appliances, and air conditioners.

These circuits allow equipment manufacturers to group related functions together on one circuit board. For example, all the relays that control an outlet can be placed on one circuit board along with their respective contacts. This reduces the number of connections to the wiring diagram compared to having each relay control several lamps or appliances individually. It also helps prevent any accidental contact with live wires when making repairs or changes to equipment located in areas accessible to the public.

The voltage is shared by all components. Resistances decrease, resulting in **a lower overall resistance**. Branch currents combine to form a bigger overall current. All of these criteria, like those for series circuits, have their origins in the concept of a parallel circuit.

In **a parallel circuit**, if one component fails or isn't connected, its share of the voltage remains undisturbed. Because there is no change in resistance, the remaining components will be able to flow as much current as before. The failed component will simply use **more energy** per second.

In practice, some components will fail prematurely because they can't handle the stress of constant current flow. Other components may not fail until they get too old or damaged to function properly. Still others may appear to work fine at first but later on cause problems with their neighbors. No matter what causes failures, it's important to identify them early so that they don't cause further damage.

Series and parallel circuits are the only two fundamental configurations available to electrical engineers. Engineers must be aware of which type of circuit they are working with if they want to design **reliable power supplies** or other electrical devices.

The voltage of all components is the same (equal). The overall current is equal to the sum of the branch currents. Residuals decrease until they equal total resistance. Residual voltage remains constant.

In practice, you cannot make **two resistors** of exactly the same value. So there will be some difference in resistance between them. This means that some current will flow through one resistor only. The remaining current flows through **the other resistor**.

If we call this first resistor R1 and second resistor R2, then R1 must be greater than R2. Otherwise, there would be no way to ensure that more than half the current could pass through R1!

Since the residual voltage remains constant, we can say that the ratio of R1 to R2 determines how much voltage is left over after all the current has passed through **both resistors**.

So, going back to our example, if R1 = R2 = 30 ohms, then the leftover voltage after both branches have passed **their current limit** will be 0.7 V. If R1 = 15 Ohms and R2 = 21 Ohms, then the leftover voltage will be 1 V.