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Interlock Vs Transfer Switch : Which Will Perform Best?

When it comes to backup power systems, two commonly-used devices are interlocks and transfer switches. But which is better? Understanding their differences will allow you to make an informed decision.

Power outages can be a serious nuisance, particularly if your life relies on electricity for medical equipment, refrigeration or other essential appliances. Backup power systems exist to keep the lights on during blackouts; however, finding the appropriate device may prove challenging due to so many available devices in the market.

An interlock and transfer switch are two popular solutions for backup power systems. While both serve the same function, their operations differ; each has their own benefits and drawbacks; choosing which device best meets your requirements depends on individual circumstances. Here, we explore their differences to help you select one.

What Is An Interlock Switch?

An interlock switch is a device intended to prevent accidents or equipment damage by verifying certain conditions before allowing machines or systems to operate. Common applications for interlock switches in industry include stopping machinery from starting up when certain conditions such as open guards, unlocked doors or other unsafe circumstances exist. They can either be mechanical or electronic in design and are often utilized alongside additional safety devices like emergency stop buttons and safety mats.

What Is the Purpose of an Interlock?

Interlocks serve a vital purpose, protecting us against accidents and damage by ensuring certain conditions are fulfilled before operating any system or device. They act as safety mechanisms by stopping it if they’re not, thus protecting against potential harm or damage to individuals, buildings or the environment. Interlocks are used across industries – manufacturing, construction and transportation among them – to ensure safe and efficient operation of equipment and machinery.

How An Interlock Works?

An interlock is a safety mechanism designed to stop machines from operating until certain conditions have been fulfilled. This often includes activation of switches or sensors in sequence before starting up the machine – for instance all doors and panels being locked or engaging the safety switch being met before an interlock will allow its start up; helping prevent accidents by making sure it’s used safely and correctly.

When Should an Interlock Be Used?

An interlock should be utilized whenever there is the need to ensure a specific sequence of events occurs in an orderly fashion, such as when operating machinery or equipment that requires specific steps for safe operation, or when electrical systems may create unintended results such as short circuits or overloads that compromise their proper functioning. Ultimately, interlocks are employed to guarantee system and equipment safety and optimal functioning.

Why Should We Use Interlock In Generators?

Interlock systems for generators are essential, as they prevent backfeeding into the grid which could endanger utility workers and damage to both itself and nearby objects. Furthermore, interlock systems ensure proper grounding for your generator while helping ensure it operates within safe operating parameters and extend its lifespan.

How Can I Select an Interlocking Device?

When selecting an interlocking device, it is crucial to take into account its application and environment in which it will be used. Factors to keep in mind include safety requirements, equipment type being utilized, regulatory constraints and any compatibility concerns with existing systems. Consulting with trusted suppliers or industry experts may also prove invaluable when finding an ideal device.

What Is A Transfer Switch?

Transfer switches are electrical devices designed to switch power sources between your main power supply and backup generators, providing your home or business with uninterrupted electricity during outages or emergencies. They automatically switch over when main power fails and back again once restored – this makes sure uninterrupted electricity in critical situations.

What Are The Types Of Transfer Switch?

1. Manual Transfer Switch

Manual transfer switches require human intervention to switch between primary and backup power sources, making them the simplest and least costly type. In case the power goes out, when manual switch off must manually be activated on or off, switching the primary source off before turning on backup sources as soon as possible. Manual switch are ideal for smaller homes and businesses who do not require much power at any one time.

2. Automatic Transfer Switch

An automatic transfer switch does exactly as its name suggests – switching automatically between primary and backup power sources without human interaction. Whenever power goes out, an automatic transfer switch detects it instantly. It switches seamlessly over to its backup source in seconds – perfect for homes and businesses that require large amounts of electricity.

3. Non-Automatic Transfer Switch

A non-automatic transfer switch is a manual switch with no built-in mechanism to switch between primary and backup power sources; an external switch or breaker must be used instead. These transfers are especially useful in situations when switching between two power sources that do not typically share one another.

Purpose Of A Transfer Switch

A transfer switch’s purpose is to transfer electricity from the main source to an alternate source in the case of a power loss or other electrical emergency. This guarantees that key equipment and systems stay operational and aids in the prevention of data destruction or loss. Transfer switches are a popular component of backup power systems in residential, commercial, and industrial applications.

How Does A Transfer Switch Work?

Transfer switches are designed to transfer power between two sources – for instance in an outage or blackout situation they will switch automatically from main power grid to backup generator or battery system. Transfer switches ensure critical appliances and systems continue running during an outage, such as medical equipment, security systems and heating and cooling systems.

They work by quickly switching over from main power source to backup source as soon as the main power fails; when main power returns automatically after restoration occurs. Transfer switches are an integral component of backup power systems used in homes, businesses and other critical facilities alike.

Why Do I Need A Transfer Switch?

Transfer switches are essential to ensure the safe and effective use of backup generators during power outages. Without one, backfeeding electricity into the grid could pose serious health and safety hazards to utility workers as well as damage to your electrical system. A transfer switch also helps control the flow of electricity between your generator and home to avoid overload and potential damages to appliances and electronics; providing homeowners who rely on them with added peace of mind and convenience.


  • A transfer switch ensures safe and efficient transfer of power during a power outage
  • It eliminates the need for extension cords and power strips
  • It prevents backfeeding, which can be dangerous to utility workers


  • A transfer switch can be expensive to purchase and install
  • It may not be necessary for all households, especially those with less critical power needs
  • It requires professional installation, which can add to the overall cost.

Comparisons Between an Interlock and Transfer Switch

1. Purpose

An interlock is designed to prevent simultaneous use of two electrical sources while transfer switches are designed to switch between them.

2. Installation

Interlocks should typically be installed in the electrical panel while transfer switches connect it with its backup power source.

3. Cost

Interlocks tend to be less costly than transfer switches as they only require a mechanical device to stop two sources from simultaneously operating while transfer switches require more complex installation procedures and could require extra wiring connections as well.

4. Convenience

Interlocks require manual intervention to switch between electricity sources, while transfer switches can either be automated or manual – the latter automatically switching over when the main source fails.

5. Safety

Interlocks provide some level of protection by preventing simultaneous operation of two electrical sources, but do not offer the same degree of security that transfer switches provide when switching between sources. Whilst interlocks provide some level of safety protection, transfer switches provide more reliable means of switching sources when making adjustments between electrical sources.

6. Capacity

Interlocks are generally intended for smaller electrical loads, while transfer switches can accommodate larger loads.

7. Noise

Interlocks do not produce any audible sound during operation while transfer switches may produce some sound when in operation.

Overall, both interlocks and transfer switches have their advantages and disadvantages. The choice depends on factors such as budget, electrical load, and the level of convenience and safety required.


Interlock and transfer switches depend on the needs and requirements of their user to fulfill effectively. An interlock switch is more cost-effective and simpler to install, but requires manual operation – potentially not suitable for larger loads. A transfer switch costs more money to install professionally but provides automatic transfer and can handle larger loads more effectively; ultimately the best choice depends on individual circumstances and user requirements.

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