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What is Isolator Switch and What Does It Do?

Rotary isolator switch

In order to keep electrical systems safe during maintenance or fault, an isolator switch is used to isolate circuits from the power source. However, given its purpose and function, you may wonder what an isolation switch is, or even how it works. Not to worry if you are curious, because we have you covered! Read on for more about this crucial safety device.

What is Isolator Switch?

An isolator switch, also often called a disconnector switch, is a type of electrical switch used to isolate an electrical circuit or equipment. It provides a physical barrier between the user and the live parts of the electrical system, thus protecting against electric shock.

Isolator switches allow for easy switching off of an electrical circuit during maintenance or fault-finding operations, and are a commonly used safety device in industrial, commercial, and domestic applications.

Generally, there are two different types of isolator switches: AC isolator switch and DC isolator switch, based on the type of electrical current that it’s meant to isolate —more about the isolator types and when to use them next.

AC isolator Switch

This type of isolator switch is used to break the current in AC circuits. You’ll often find it in homes and buildings that are connected to the power grid. An AC isolator switch should not be used in DC circuits since its design is only meant for AC.

The AC isolator switch is also usually located between the meter and the consumer unit. Here, it provides a safe and convenient way to disconnect from the grid from the various circuits as needed.

DC Isolator Switch

This is a DC load isolator switch. What this means is that it works in direct current (DC) circuits, but serves the same purpose as the AC isolator switch.

DC isolator switches are commonly found in solar power systems where they disconnect the solar array from the rest of the system. In this application, the DC isolator is mounted between near the solar panels or close to the solar inverter, but on the DC side.

Isolator switch wiring diagram (single phase)
Isolator switch wiring diagram (single phase)
Resource: https://youtu.be/pg9VUfQ7jLg

What Does an Isolator Switch Do?

Or, in other words, what is the isolator switch purpose? The main function of isolator switch devices is to provide a safe way to disconnect a circuit from its power source. This allows it to be serviced or repaired while ensuring no risk of electric shock.

Note that the isolator is normally used after the circuit has been switched off by the circuit breaker. This is because the circuit breaker can handle the arcing that may result, while the isolator cannot. To help you understand this better, here is a simple explanation:

Isolator Switch Function

When you turn on an isolator switch, it creates a physical barrier between the user and the power source. This makes it impossible for any current to flow through the circuit until the isolator switch wiring is live (or turned on) again.

In other words, when the switch is in its “OFF” position, it completely prevents current from flowing through the circuit. This is why isolator switches are so important – they provide a way to keep your equipment, and yourself, safe while working on an electrically powered machine or system.

Isolator Switch Working

So, how does an isolator switch work? The inside of the isolator switch is made up of a series of contacts, usually high conductivity metal, that act as connections between the power source and the equipment.

When the switch is in its “ON” position, these contacts are connected, allowing current to flow through the circuit. When it’s in its “OFF” position, however, these contacts are disconnected, which prevents any current from flowing through the circuit.

The isolator switch handle (or other switching means) allows for easy ‘ON/OFF’. Most often, and especially where there is the danger of electrocution, a lockable isolator switch is necessary. This prevents any unauthorized access, and helps to ensure the safety of all personnel.

Isolator Switch Vs. Switch

Given that both switches are used as safety devices to control the flow of electrical current, there is often confusion between isolator switch and regular switch. So how do the two devices compare?

The main difference between isolator and switch lies in their purpose; whereas a normal switch controls the flow of electricity through a circuit, an isolator switch is designed for safety purposes.

In essence, a normal switch disconnects an appliance or circuit in the on-load condition while an isolator switch disconnects a circuit in the off-load condition. This makes isolators much safer than normal switches, as there is no danger of electric shock.

How to wire isolator switch
How to wire isolator switch
Resource: https://www.youtube.com/watch?v=_d_KlW8UZwE

How to Wire Isolator Switch

An isolator switch is wired to the circuit that it’s meant to control in order to provide a safe method of cutting off power. This should be done by a qualified electrician and with the help of an appropriate wiring diagram. The isolator switch installation and wiring procedures are explained below.

Isolator Switch Installation

Isolator switch installation involves different mounting methods. These include base mount, DIN-rail mount and panel mount. Depending on the type of installation, electrical wiring is done accordingly. To install an isolator switch correctly, the following rules should be followed:

  • Ensure that the power supply is disconnected.
  • Match the load type and voltage isolator switch rating with that of the circuit.
  • Install the isolator switch in accordance with local regulations and codes.
  • Make sure all electrical connections are tight and secure.

Isolator Switch Wiring

The isolator switch wiring procedure is based on the type of installation or power system type, and may vary from one setup to another. Generally, the wiring involves these steps:

  • Connecting the power supply wires to the terminals of the isolator switch.
  • Connecting device or appliance’s load wires with corresponding terminals of the isolator switch.
  • Connecting the ground wire, if required.

Once the wiring is done and all connections are secure, test the circuit for any errors or short circuits by switching on the isolator switch. If everything seems to be in order, then it’s safe to use the circuit.

Isolator Switch Price

The cost of isolator switch depends on its type and rating. Generally, the price of a standard single-pole isolator switch ranges from $20 to $100. For multi-pole switches, the price range starts from about $100 and goes up depending on the number of poles and amperage ratings.

The range of isolator switch price also varies from one manufacturer to another. As such, it would greatly help to compare prices from different sellers before selecting one. While at it, ensure that the isolator switch manufacturer you choose offers good quality and reliability for a more lasting solution.

Conclusion

To sum up, an isolator switch is a critical component of any electrical system. It provides protection from potential dangers associated with live wiring and enables convenient switching on/off of the circuit. When selecting an isolator switch, ensure that it matches your type of electrical system and complies with necessary safety regulations.

Related Resource

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