Connectors

Banana Plugs & Sockets

CT CT61

The bananas and the terminals or panel sockets are single-pole connectors frequently used in the connections of power supplies in the electronic laboratory, workshop, etc.

What is a banana connector?

A banana plug is a type of electrical connector commonly used in electronic and laboratory equipment to establish temporary connections between devices. The female consists of a cylindrical plug with a hollow end into which a banana-shaped male connector is inserted. These connectors are especially popular in audio applications and electronic instrumentation as they provide a secure, low electrical resistance connection. Banana plugs are typically used to connect cables to devices such as speakers, amplifiers, multimeters, and power supplies. Their design allows for quick and easy connection, making them very practical in environments where frequent testing and measurements are carried out.

What sizes of banana are there?

Basically 2 and 4 mm diameters are used, but there are other different sizes:

1 mm: It is quite rare but some manufacturers such as Stäubli make banana plugs in this very tiny size.
2 mm: This size is usually used when a small size is required.
3.5 mm: It is a rarely used size. Fundamentally used in modeling or radio control equipment, for connecting batteries.
4 mm: This type is the most widely used by far. Both laboratory power supplies, multimeters and other instrumentation equipment, speakers, etc. They generally use the 4 mm banana.
6 mm: This size is used in potential equalization connections, mainly in operating rooms or/and hospitals. Additional potential equalization aims to equalize the electrical potentials between several metal parts that could be touched at the same time. This is done to minimize potential differences that may arise during operation between the bodies of electrical medical devices and other conductive surfaces. In short, its purpose is to ensure electrical safety by reducing the possibility of electric shock when touching different metal parts simultaneously.

Security systems used in banana connectors

To prevent accidental contact with the banana contacts and ensure the electrical safety of the user, several safety systems are used in these connectors. Some of the common security measures include:

Plastic insulation: Bananas often have a plastic coating around the metal contacts to electrically insulate them and prevent direct contact with fingers or other conductive objects.
Protective covers: Some bananas are designed with retractable protective covers that cover the contacts when not in use. These covers slide back when the banana is inserted into a connector, and automatically close again when removed.
Safety Covers: Another approach is to use fixed safety covers that surround the banana contacts. There are two types of connection covers.
- Fixed: These covers are fixed and the male connectors are only valid for sockets with a security system. This coating trips when trying to connect to a non-safety socket.
- Retractable: These covers only open when the banana is pressed against a corresponding connector, preventing fingers or other objects from coming into contact with the metal contacts. Retractable sleeve plugs can no longer be
  exposed to hazardous voltages during handheld use. Therefore, the rated voltages of such
  items have been downgraded to 30 VAC ~ 60 VDC.
Safety design: Some bananas are designed with features that make it difficult or impossible to touch the contacts directly, even if you try to insert a thin object. For example, the contacts may be located at the end of an elongated housing, requiring a specific connector to be inserted.

These safety measures are designed to minimize the risk of accidental electrical shock when handling banana plugs. However, it is always important to handle these devices with care and follow proper electrical safety practices.

Guide to Measure and Test Safely

Bananas are electrical connection elements in which it is important to emphasize safety in the measurement. Concerns about safety and usability issues of test accessories in compliance with applicable standards are raised again and again. Therefore, it is necessary that this matter be explained, as it can be somewhat difficult to understand. This section " provides you with useful information to facilitate the selection and proper use of test accessories.

In addition to providing an overview of the most important applicable standards and directives, it also addresses current changes to the industry standard IEC 61010-031, the most important for the safety of electrotechnical test accessories.

We have also included in this section a glossary with explanations of terms related to measurement and test accessories.

Each measurement situation presents a new challenge for the user and for the measurement and test accessories used. Each industry, each application field and each voltage environment are different. For that reason, whether for test probes, test clips or plug-in connectors, the crucial parameters are always the same: the safety, reliability, ease of use, precision and strength of the test accessories. To simplify the classification of test accessories to be used in each application, the IEC 61010-031 standard has specified several categories that determine where on the mains power supply the work can be carried out and what corresponding requirements are set for the respective voltage. What is crucial is the power available in the event of a fault (e.g. short circuit or overvoltage) in the corresponding measurement category.

There are several measurement categories, abbreviated as "CAT" followed by a Roman numeral. In general, the higher the CAT number, the stricter the product safety requirements.

For the extra low voltage range (up to 30 VAC / 60 VDC), it is assumed that contact with non-insulated live parts can be classified as harmless. However, if the extra low voltage is supplied via a power adapter, there is always a connection to the mains power supply. People with pre-existing conditions (especially heart disease) should in particular avoid contact with electrical voltage in general. Therefore, the general use of touch-protected test accessories is recommended; Consideration should be given to what a failure in the mains power supply or a possible overvoltage in the mains could mean. If proper precautions are taken, testing can be performed safely in electronics laboratories and educational institutions, as well as by electronics hobbyists at home.

As a minimum, touch-protected test accessories in accordance with IEC 61010-031 are essential when the user performs measurements on circuits that are directly connected to the low-voltage network. Therefore, in addition to measurement results, safety always plays a crucial role, whether for service technicians in repair shops (CAT II) or electricians and employees of power supply companies (CAT III and CAT IV).

Mandatory: specialized knowledge

Maximum safety when working with electrotechnical test accessories should be the top priority for you as a user. Test fixtures obviously require training or certified specialist knowledge.

The selection of test accessories should be carefully considered.

However, to prevent accidents, it is equally important to consider in which situations the test is performed. Accessories will be used from the selection phase.

How is the measurement task organized and carried out? How can you access the measurement point?

The user of the test fixture should familiarize themselves with the topics listed below before starting work. Practical considerations for performing the task: Tap shape, exclusive use of portable test accessories (test clips, test probes, etc.), or installation of special adapters.

What voltages and currents can occur? i.e. are the capabilities of the test fixtures sufficient for the planned applications?

The test accessories should be designed for voltages and currents that are at least as high as the highest anticipated voltages and currents. As far as possible, ratings are mentioned in catalogs and attached to products.
Please note the product information and, if applicable, the included documents (e.g. user information)!
However, in certain cases, there is not enough space on the products for technical information. Then you will find the symbol, which
refers to the included documents.

Where in the network is the electricity supply located?

The user must be clear about where the work will be carried out and the dangers that may arise in each particular case depend largely on the position within the installation.

What are the environmental conditions of the object being measured? What contamination is expected for the intended use?

For the use of electrical test accessories, it is important to know the environmental conditions. The user must take into account whether, for example, contamination or humidity is expected. Proper use is a prerequisite for the safe handling of test accessories.
In a specific case, proper use means grasping a portion of a test fixture where the handle area or under guard is provided.
shroud, for example.

Use or improper use of damaged products carries high and unpredictable risks.

Additionally, we would like to point out that occupational safety in the workplace remains ultimately the responsibility of test accessory users, as it depends on them actually using test accessories (correctly) that are appropriate for their needs. purposes. In fact: Testing accessories + correct use = occupational safety

Summary of directives and regulations applicable to measurement equipment, including banana plugs and accessories

Local laws and standards
Example: EU

• EU Directive 2001/95/EC
“General Product Safety”
• EU Directive 2014/35/EC
“Low Voltage Directive” CE

Example: USA and Canada

• USA: National Electrical Code (NEC)
• Canada: Canadian Electrical Code (CEC)

International laws and standards

Safety requirements for electrical equipment for measurement, control and laboratory use.

IEC 61010-1
• Part 1: General security requirements

Safety requirements for electrical equipment for Measurement, Control and Laboratory

This standard, Part 1 of IEC 61010, establishes general safety requirements for the following types of electrical devices and their accessories, regardless of where the intended device is used.

• Electrical measurement and testing instruments.
• Electrical control and regulation devices for industrial process control technology.
• Electronic laboratory devices.

The purpose of the requirements of this standard is to ensure that risks to the user and the environment are reduced to an acceptable level.
For portable test accessories for measurement and testing, the IEC 61010-031 standard must be followed.

IEC 61010-031
• Part 031: Safety requirements for portable probe sets for electrical measurement and testing.

Part 031 of the IEC 61010 series of standards contains safety requirements for portable and manually operated test accessories and accessory parts.
These test accessories serve as an interface between an electrical phenomenon and a test or measurement instrument. They can be permanently connected to the measuring instrument or be plug-in accessories for instruments.
The purpose of the requirements of this standard is to ensure that risks to the user and the environment are reduced to an acceptable level.
Requirements for protection against special hazards are handled as follows:

• Electric shocks and burns.
• Mechanical risks.
• Excessive temperatures.
• Fire spread from test fixtures.
• Electric arc

IEC 61010-2-030
• PART 2-030: Particular requirements for equipment having test or measurement circuits

IEC 61010-2-33
• PART 2-033: Particular requirements for portable multimeters and other portable meters, for domestic and professional use, capable of measuring mains voltage.

Classification et subdivision des fiches bananes et autres accessoires de test selon CEI 61010-031

To simplify the classification of banana plugs, banana sockets and test accessories to be used in each case, the IEC 61010-031 standard has specified several categories that determine in which part of the electrical network the work is located and establishes the requirements that apply. to the respective category.
The measurement categories currently specified in the standards used (until 2002) to be called surge categories. The term was based on the fact that the classification mainly focused on anticipated (transient) overvoltages in a power grid. The measurement categories no longer differ so much in the level of expected transients, but rather in the power available in the respective measurement category in the event of a short circuit. More energy can be released, in a higher measurement category, than in a lower one, all paths lead to explosive results, with very serious consequences for the user.
There are three different measurement categories in the standard, abbreviated "CAT." You will find CAT followed by a number.
In general, the higher the CAT number, the higher and stricter safety requirements for the product. Other circuits that are not directly connected to the network are excepted.

Devices without specific category

Many types of test and measurement circuits are not intended for direct connection to the electrical grid. Some of these measurement circuits are only suitable for low voltage power applications. However, other of these measurement circuits may be exposed to large amounts of available power due to high short circuit currents or high open circuit voltages. Therefore, to establish the requirements for these applications, it is necessary to know what surges may arise.

Measurement Category II (CAT II)

It applies to test and measurement circuits that are connected directly to the user terminals (sockets and similar terminals) of the low-voltage network.
Example: measurements in power circuits. of household appliances, portable tools and similar devices and exclusively connected to fixed installation outlets.

Measurement category	Short circuit current (typical)	Area of the building installation
CAT II	< 10 kA	Circuits connected to power outlets and similar points within the grid installation

Measurement category III (CAT III)

It applies to test and measurement circuits that are directly connected to the distribution circuit of the building's low-voltage electrical network. To avoid risks arising from hazards caused by these higher short circuit currents, additional insulation and other measures are required.
Example: Measurements on distribution boards (including output meter circuits), on photovoltaic modules, on circuit breakers, on wiring, on busbars, circuit breaker panels, switches and sockets of the permanent installation, on industrial appliances and some
other devices such as stationary motors with a fixed terminal.

Measurement
category

Short circuit current
(typical)

Area of the building installation

CAT III

< 50 kA

Power distributors in buildings

Measurement category IV (CAT IV)

Apply a safety and medical circuit that is connected to the power point of the low voltage installation of the building. Allow the high currents of the circuit to operate. Debido a los altos niveles de energía, las mediciones aquí son muy peligrosas. Be sure to take precautionary measures to prevent a possible cortocircuito.
Example: Medications on devices that were installed before the main fuse or disconnector when installing the building.