Electrical Inspection Testing – A Guide to the Basics
What is Inspection?
It is carried out before the testing and the installation is normally disconnected from the supply.
The point of inspection is to verify that the installed equipment:
Complies with relevant standards – this is normally a mark of certification by the installer or manufacturer
Is the correct type and installed in accordance to the Regulations
Not damaged or defective which would cause a safety issue
The Inspection includes the checking of several items which are relevant to the installation. The checking can also take place, if necessary, during installation. The items checked are listed in Regulation 611.3 ‘Inspection’ BS7671.
What is testing?
It is important that testing is carried out using the correct equipment and methods and the results are compared with relevant criteria contained in Regulations 612.2 to 612.13
Testing also needs to be carried out in a specific order before the installation can be switched on. The test order is detailed in Regulations 612.2 to 612.6
If any part of the testing fails to comply, that test plus any other testing already carried out has to be repeated once the fault has been fixed. This is because the results of the tests may not be accurate and may have been influenced by the fault.
Electrical Inspection and Testing Procedures
Regular testing and inspection of both fixed electrical installations and portable appliances, completed by qualified electricians, is the most effective way to ensure compliance with health and safety law.
Identifying and rectifying defects helps to maintain safe functioning of electrical equipment. Testing should consist of both scheduled visual inspections and tests. Electrical inspection and testing procedures are determined by the type of installation:
- Initial Verification Inspection and Testing: For new build or alterations to fixed electrical installations
- Periodic Inspection and Testing: Fixed wire tests of existing electrical installations
- Portable Applicance (PAT) Testing: Portable electrical appliances
Testing should be performed by qualified electrical engineers, experienced in electrical inspection and testing procedures and use of the relevant testing equipment. In addition, basic, visual inspections of electrical equipment (both fixed installations and portable appliances) carried out on a regular basis can identify wear, tear, faults and defects before developing into a serious hazard.
Electrical inspection and testing procedures should be approached on a planned, preventive basis, taking into consideration:
- Appropriate frequency of testing and inspection
- Record keeping
- Equipment labelling
Four myths about electrical safety that may surprise you
Plant safety is much more than just tasks on a checklist. It requires a commitment from every employee—from management to line workers—to maintain a culture of safety in all aspects of the operation. Over time, interpretations of certain safety standards can stray from the original intent creating some myths about how best to meet safety requirements.
Myth #1: “Inconvenient” is the same as “infeasible” when it comes to de-energizing equipment for maintenance
There’s no doubt that it is almost always inconvenient to shut down power unexpectedly to work on a piece of equipment. But that doesn’t mean it’s infeasible. The Occupational Safety and Health Administration (OSHA) permits working on an energized circuit only under certain conditions, including when it’s “infeasible” to shut down power due to increased hazard. However, there is a tendency to allow employees to work on live circuits just because it’s “inconvenient” to shut down power. This adds unnecessary risk that often leads to accidents.
In situations where it actually is infeasible to shut down the power, only electricians and technicians qualified to work on energized systems should perform the work. They should take all precautions, including wearing proper personal protective equipment (PPE) and using tools certified for the conditions they encounter.
Myth #2: The more PPE the better
Whether to wear PPE, and how much to wear, are not personal decisions. A component can fail at any time. Perfectly good breakers can fail suddenly during troubleshooting. If an arc flash occurs while simply opening a cabinet, wearing the correct PPE can mean the difference between surviving or not. Electricians and technicians must follow the detailed PPE standards developed by the National Fire Protection Association (NFPA) 70E Standard for Electrical Safety in the Workplace. However, requiring workers to wear PPE rated for a much higher hazard level than the environment calls for will not necessarily make them safer.
“More PPE is not necessarily better,” says Kevin Taulbee, Electrical Engineer and Safety Trainer at Power Studies, Inc. “Having the right PPE is what counts. Performing proper job hazard analysis is important for equipping workers with the correct PPE. Too many people just go out and purchase arc flash moon suits and thick, high voltage linemen gloves for their in-house maintenance and electrical workers. Class 2 electrical gloves aren’t necessary if they never get into anything over 480 volts and they offer much less dexterity. As a result, an electrician may be more likely to drop a tool or lead when working in an energized panel.”
Myth #3: All test leads and fuses are created equal
Often technicians regard test leads and fuses as basic commodity components without giving quality much thought. Regardless of the quality of the multimeter, it’s only as safe as the test leads used with it and the fuses inside. These components provide critical protection against power surges and voltage spikes that can cause serious injury to the user.
Choosing the right test leads
The primary job for test leads is to connect the digital multimeter to the equipment being tested, but they also provide a first line of defense against electrocution. Test leads that are poorly made, worn, or aren’t rated for the job at hand, can produce inaccurate readings and may pose a serious shock hazard if touched to the wrong wire. When choosing test leads look for:
High quality materials and rugged construction
Rating for the appropriate category and voltage level of the application. The CAT rating on the leads should match or exceed the category of the DMM.
Exposed metal that matches the energy potential of a specific measurement.
Retractable probes, probe tip covers, or probes with shorter tips to avoid an inadvertent short circuit.
Pick high quality replacement fuses
Today’s safety standards require digital multimeters to include special high-energy fuses that are designed to keep the energy generated by an electrical short, within the fuse enclosure. This protects the user from electric shock and burns. When it’s time to replace fuses always choose the high energy fuses approved by the meter’s manufacturer. Cheaper generic replacement fuses increase the risk of serious injury.
Myth #4: The only way to accurately measure live voltage is with test lead contact.
In the past, attaching test lead probes or alligator clips directly to electrical conductors was the best way to get accurate results. However, this requires metal-to-metal contact, which increases the risk of arc flash and potential harm to both the person doing the measuring and the equipment being measured.
Recently a new technology was introduced that detects and measures voltage without metal-to-metal contact. This technology isolates the measurement tool from the voltage source under test. To measure voltage, electricians and technicians just slide a single conducting wire into the open fork of the handheld test tool. Since they aren’t exposed to contact points with live voltage, the risk of electrical shock and arc flash is reduced.
The myths listed above represent just a small sampling of the safety issues to be considered when working on energized equipment. The best way for a facility to ensure that employees fully understand and follow all the relevant electrical safety regulations is to develop and maintain a solid safety culture based on the needs and environment of that specific facility.
Software Testing – Levels
There are different levels during the process of testing. In this chapter, a brief description is provided about these levels.
Levels of testing include different methodologies that can be used while conducting software testing. The main levels of software testing are −
- Functional Testing
- Non-functional Testing
This is a type of black-box testing that is based on the specifications of the software that is to be tested. The application is tested by providing input and then the results are examined that need to conform to the functionality it was intended for. Functional testing of a software is conducted on a complete, integrated system to evaluate the system’s compliance with its specified requirements.
There are five steps that are involved while testing an application for functionality.
I The determination of the functionality that the intended application is meant to perform.
II The creation of test data based on the specifications of the application.
III The output based on the test data and the specifications of the application.
IV The writing of test scenarios and the execution of test cases.
V The comparison of actual and expected results based on the executed test cases.
An effective testing practice will see the above steps applied to the testing policies of every organization and hence it will make sure that the organization maintains the strictest of standards when it comes to software quality.
Let’s see more details about these Testing types.
It is the most common type of testing used in the Software industry. The objective of this testing is to identify all possible issues or defects before releasing it into the market or to the user.
Alpha Testing is carried out at the end of the software development phase but before the Beta Testing. Still, minor design changes may be made as a result of such testing.
Alpha Testing is conducted at the developer’s site. In-house virtual user environment can be created for this type of testing.
An Acceptance Test is performed by the client and verifies whether the end to end the flow of the system is as per the business requirements or not and if it is as per the needs of the end-user. Client accepts the software only when all the features and functionalities work as expected.
It is the last phase of the testing, after which the software goes into production. This is also called User Acceptance Testing (UAT).
The name itself suggests that this testing is performed on an Ad-hoc basis i.e. with no reference to the test case and also without any plan or documentation in place for such type of testing.
The objective of this testing is to find the defects and break the application by executing any flow of the application or any random functionality.
Ad-hoc Testing is an informal way of finding defects and can be performed by anyone in the project. It is difficult to identify defects without a test case but sometimes it is possible that defects found during ad-hoc testing might not have been identified using existing test cases.
The aim of Accessibility Testing is to determine whether the software or application is accessible for disabled people or not.
Here, disability means deaf, color blind, mentally disabled, blind, old age and other disabled groups. Various checks are performed such as font size for visually disabled, color and contrast for color blindness, etc.