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What is a Combination Circuit?

This article covers a ‘combination circuit’ type and shows how it is used in various applications, including lighting and appliances.

Simple circuits have elements that are either connected in series or parallel. When the two methods are combined in a single circuit, such circuits are described as combination circuits. In other words, a combination circuit is a type of circuit that combines series and parallel electrical circuits.

This arrangement makes a combination circuit useful in various ways.

The combination of electrical elements arranged in series and parallel in the same circuit, which we call a combination circuit, is useful in many appliances and lighting circuits. It allows us to combine the advantages of each type and avoid or minimize their disadvantages. In particular, it is often suitable for high-powered appliances, keeping a check on the current level, components that need to control a group of circuit branches, and simplifying complex wiring, for example, to reduce the cost of an appliance.

Understanding a Combination Circuit

A combination circuit combines both series and parallel circuits, so we need to understand them first:

  • A series circuit is one in which the current flow has only a single route. In these circuits, the current flow remains the same across each component or load in the circuit, but the voltage is divided between them.
  • A parallel circuit is a circuit that has two or more routes for current flow. All components or loads in these circuits have the same voltage, but the current is divided between them.

When the above arrangements (series and parallel) are combined in the same circuit, the circuit forms a combination circuit.

A combination circuit may comprise, for example, various resistors, light bulbs, or other loads that are linked together in a combination of both series and parallel paths.

Analyzing a combination circuit requires analyzing the series and parallel parts separately.

The illustration below shows the difference between a series, parallel, and combination circuit.

Next, we will look at some useful applications of the third type after first highlighting some advantages of the combination circuit design.

combination design circuits

Advantages of Combination Circuits

Consider the above lighting circuits in series and parallel to understand how the arrangement of components or loads makes a difference.

Series circuits are useful when you need to maintain the same current through each component, whereas parallel circuits are useful when maintaining the same voltage across them.

If any light bulb in a series circuit goes out, the rest will go out as well, and while working, the more bulbs connected in a series, the less bright each one will be due to the divided voltage.

In a parallel circuit, this does not happen, so the brightness of any one bulb is unaffected, and if any light bulb fails, the others will remain lit.

It might seem like a parallel circuit has an advantage, which it does if you want to ensure at least one light bulb is always lit, but series circuits have the advantage of needing less current to operate.

A combination circuit has certain advantages over both of the other two types of circuits (series and parallel) because it has properties of both:

  • It provides several paths for the current to flow.
  • It allows a single power supply to simultaneously supply electrical power to multiple devices.
  • Combination circuits are relatively easier to design.
  • Overheating does not occur quickly in a combination circuit.

Uses of Combination Circuits

Combination circuits have found their way into various appliances, lighting solutions, and other electrical devices.

Lighting Circuits

simple circuit for lighting

Lights can be connected in either series, parallel, or combination.

If they are connected in series, they will share the same circuit and depend on each other for functioning. Other advantages and disadvantages of this approach were mentioned earlier. They will have their own independent branch if they are connected in parallel.

Generally, a parallel arrangement is preferred because it is simple, safe, and reliable and has several advantages [Alexander & Matthew]. In particular:

  • Adding more bulbs will not reduce the brightness.
  • Each bulb can be turned on and off separately.
  • A circuit break in any branch will not affect the lights functioning in the other branches.

However, if the lights are connected in a combined arrangement instead, some may be in series while others are in parallel, so the benefits and drawbacks of both will be present.

To offset the disadvantages of parallel circuits, a combined circuit:

  • Less cabling needs to be used.
  • Less complex wiring design.
  • Keep a check on the current to prevent it from getting too high.


home electrical appliances

Appliances can similarly take advantage of combined circuit arrangements.

In particular, combination circuits are advantageous for:

  • High-powered appliances draw a lot of current to have some elements in series to keep the current low.
  • Appliances that need to have some element control a whole group of parallel branches, such as an indicator light showing all branches are functioning.
  • Simplifying complicated wiring designs can also reduce the appliance’s cost.

Components that need to control the entire circuit, such as a main switch, will be set in series. Also, a fuse or circuit breaker is always connected in series because it needs to cut off power to the entire circuit in case of a fault, such as when the current is too high.

Here is a list of common practical uses for combination circuits:

  1. Lighting and outlets: A combination circuit can power lighting fixtures and outlets in a room or area. This allows you to use the same circuit to power both lighting and outlets, which can be convenient and efficient.
  2. Appliances and outlets: A combination circuit can power appliances and outlets in a kitchen or other area.
  3. HVAC and outlets: A combination circuit can power heating, ventilation, and air conditioning (HVAC) systems and outlets in a home or building.
  4. Outdoor lighting and outlets

It’s important to note that combination circuits should be properly sized and protected to ensure they can safely handle the load of all the devices and appliances connected to them. It’s always a good idea to consult with a licensed electrician or refer to the National Electrical Code (NEC) for guidance on the safe installation and use of combination circuits.

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About Sam Orlovsky

AvatarCertifications: B.E.E.
Education: University Of Denver - Electric Engineering
Lives In: Denver Colorado

Electrical engineering is my passion, and I’ve been in the industry for over 20 years. This gives me a unique ability to give you expert home improvement and DIY recommendations. I’m not only an electrician, but I also like machinery and anything to do with carpentry. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share.

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