There are two things you want in your facility. First, you need the gear to deliver optimal and consistent performance. Additionally, the equipment shouldn’t cause any damages or accidents with injuries. Live testing can help to maintain both goals. It involves checking if the gear works right while it’s operating. But, there is something you should know before working near or around the energized equipment.
What Does Live Testing Mean?
Caption: An electrician working on maintaining electrical equipment
If you handle electric testing sessions, you should turn off the power supply to the gear. The experts recommend deactivating it for personnel safety. The problem is that you can’t test a device’s performance without checking how it works.
Live testing involves checking the system while the power supply is active. It helps in finding faults, but it also carries more significant risks. Therefore, you should ensure trained electricians handle the action. The experts suggest that live testing is possible on all gear and conductors that work at no less than 50 volts.
The Electricity at Work Regulations suggests when live testing should occur:
- If the device vitals need to remain “live” at all times.
- It’s possible for the electrician to do the checks while the device is “live.”
- If you take all precautions to maintain safety and prevent injuries.
Tests That We Carry Out “live”
The device list is up to you to decide. As for the series of tests to take, here are the ones that the experts recommend.
This test involves circuit breakers, switches, and fuses. In other words, these are single-pole devices with a connection to the PHASE conductor. The idea is to confirm the relationships are optimal. That way, we ensure the electricians did the setup right. It minimizes the damage risk for the entire apparatus. And you’ll only need a plug-in tester. You’ll read the numbers on the charts to confirm correct polarity.
Earth Loop Impedance Test
Let’s assume that a fault occurred in the electrical system. The circuit breaker or fuse should get enough current flow to protect the faulty circuit. It ensures that the earth cable resistance is low enough for it to continue operating correctly. You do loop tests to see if the circuit disconnects on time to keep a fire or to overheat from happening.
You can use no-trip testing with three wires. The loop testing involves connecting these to earth, neutral, and live conductors. Make sure the test current isn’t higher than 15mA. The process won’t trip MCBs, and you don’t have to go around RCBOs and RCD. That ensures you save time with this test.
Prospective Short Circuit Test
Caption: Technician testing a control panel
If this fault happens, the cable should handle enough current to blow a fuse or trip the MCB. The guidelines indicate this should happen within five seconds for fixed gear, and however, the time reduces to 0.4 seconds for any portable equipment. The prospective short circuit test ensures the cable handles the fault as you expect.
During this test, you check the current in live conductors when a fault occurs. It’s necessary to check Line to Neutral and Line to Line in three-phase setups. For single-phase installations, check Line and Neutral. Furthermore, write down the result in hundreds of amps.
Residual Current Device Test
If an electrical fault occurs, there should be a safe RCD “tripping.” You will trip it on purpose during this test. That way, you confirm it works quickly if a fault happens. The RCD will turn off all the channels where the circuit receives power if it doesn’t trip.
The residual current device test is vital to keep electrocution incidents. Here is how to do it:
- First, connect the equipment and adjust the desired RCD rating. The test starts with half of the rated tripping current of the device.
- If the RCD doesn’t trip, increase to the rated tripping current. The average time to trip out is 0.3s.
- Increase the test rating to 5x of the rated current. You should note that the RCD takes less time to trip than in the previous step. The change will only be minimal.
Electrical Lnjury Risks When Fault Finding and Testing on Energized Equipment
The problem with live testing is that it includes significant health hazards. After the device selection, make sure to minimize the risks of potential issues. Here are the problems that might happen!
Caption: An illustration of an electrical shock
If the electricity goes through your body, you have an electric shock. The consequences might be dangerous and even fatal. Electric shocks can cause severe burns on the surface but also inside your body. They can lead to a fall because they make you lose your balance. It’s also possible a shock starts to contact with a conductor with a higher voltage. You might also have problems making any movements, or your moves might be involuntary.
This term also refers to an electric shock. However, electrocution describes a severe injury or fatal consequences of the shock. The health risk depends on various factors and not only the voltage. You also need to assess how much current goes through the body and how long.
Your breathing can stop if the current of as little as 30mA (1 amp) goes through your organism. Winds over 1A can cause permanent damage to cells and burns. A standard 125V circuit in households can send 15Amps of current to your body. Therefore, it’s hazardous, and caution is necessary when dealing with electricity.
Caption: A spark explosion
A significant electrical explosion happens when an arc fault happens. The first byproduct of that event is an arc flash. That includes heat and light that come from the blast.
Caption: how arc flash looks
If we are talking about the temperature, it can go up to 19,000C, and the usual range is about 3,000C. As a comparison, the Sun has a temperature of 5,000C on its surface. The heat from the arc flash can burn your clothing, skin, and even internal organ damage. Therefore, it could have serious consequences.
Apart from the flash, the explosion will create an arc blast, and it’s a pressure wave that forms around the device that explodes. The shots are strong and can throw you on the other side of the room. Furthermore, they are loud, so you could deal with hearing damage. Even your brain functions are in danger.
It’s not only the people who the blast can throw around. The product can throw machinery and tools around, which can also hurt you.
The dangers above can involve burn injuries. So, they are a significant health hazard to the electricians and people in the facility. The burn degree can vary on factors such as how close you are to the arc flash. Some burns might be superficial, but others can be dangerous and even fatal.
What Can You Do to Minimize Health and Safety Risks?
The actual regulations depend on your location. However, here is what you should consider when testing public devices.
Assess the Risks First
Caption: Risk assessment illustration
What can go wrong during the live or “near-live” testing? You should hire a qualified person to assess the risks. Apart from the arc flash and direct electric shock, you should consider conductive materials, and these have paths that the prospective fault current can follow to cause a shock.
Here is how risk assessment works:
- A qualified staff member should assess the current situation. That involves finding potential electrical and other risks during the test. Make sure it’s comprehensive coverage of potential hazards.
- The testing should comply with any laws and regulations.
- There should be a risk assessment report in writing.
- The report should contain suggestions on how to manage the risks.
Don’t Forget the SWMS
This is short for a Safe Work Method Statement, and the regulations require it. You need a qualified person to write it, and this report can include the actual risk assessment.
Here is how writing SWMS works:
- Talk with any relevant workers to find potential risks.
- Discuss which work is a part of the plan for the test.
- What measures can help to manage the risks? It should include additional info on each risk control action. Additionally, it should review if the relevant staff takes that action.
The person doing the test should be aware of the SWMS. If you change any work or safety procedures, you might need to change this document, too.
Use Personnel with Adequate Training
It’s needless to say that a professional should do real-time testing. They should understand how devices work and know how to use relevant instruments. Furthermore, they should also be aware of safety issues. Knowing how to act to minimize risks is vital for safety, and it ensures that the ongoing testing efforts and the process go smoothly.
The Importance of the Protective Gear
The industry experts call this personal protective equipment (PPE). It’s vital to adjust it to the needs of the individual tests.
Here is what protective equipment staff should use:
- Face. The individual should wear a full shield in case of an arc flash. Check the availability status of the shield before beginning the test. Additionally, don’t wear spectacles with metal frames.
- Gloves. What voltage do you expect? The authentication options should only include gloves that can handle the expected voltage.
- Clothing. The highest thermal rating with flame-resistant materials is the smart move. You don’t want to wear synthetics or flammable material.
- Footwear. Your shoes might be conductors. Make sure they aren’t before you enter the pre-production test environment.
Safety Barriers, Signs, and Observers
Caption: A warning sign
A safety barrier helps to avoid any contact with a dangerous part of the electrical setup. For individual tests, you’ll need to assess whether these barriers are necessary. There shouldn’t be issues with an unauthorized request because safety is everyone’s top priority.
You can use plastic, wood, or another non-conductive material for the barrier. Make sure the border won’t fall if you accidentally hit it. It’s the minimum version of sturdiness it should have.
It would help if you had safety signs, too. These are warnings to people who might enter the test area, and you can avoid a civilian disrupting the ongoing testing efforts and potentially suffering injuries.
The regulations also recommend a safety observer. For each piece in the device list, they monitor optimal risk management on the spot. If an emergency occurs, the observer should act to minimize the risk. Knowing the facility and device details can help with that.
The observer should talk to the staff member doing the test. And forget about mobile devices because communications need to be direct and effective.
If you deactivate the power supply, don’t rush with energizing the devices. Here is what you need to confirm first:
- Check if you removed any waste or private devices you used during the individual tests.
- Place covers and guards back in their places.
- Make sure to remove and note any temporary earthing equipment or electrical bonding.
- You need to warn employees that you finished unit tests and plan to turn on the power.
What If You Don’t Finish the Work?
A single day might not be enough for the entire assembly of tests. If that happens, you can leave the unit tests for another time. However, make sure that the place remains safe.
The safety actions when postponing application testing include:
- Shroud or terminate exposed conductors. Furthermore, you should physically secure them.
- Make sure to place warning signs about the tests on any device windows you plan to check
- Put additional information panels for other employees to avoid potentially risky areas.
- Make sure you inform the workers about the current index status. That way, you ensure they can continue to work safely.
Use Approved Equipment
Here is another crucial safety point. If you want to test an actual device, use only approved equipment to ensure accurate testing results and show precise device vitals. If you don’t have adequate equipment, don’t use an alternate version, which increases the risk of something going wrong. Make a careful device selection and use only proven instruments during the entire testing timeframe.
Caption: Electrical equipment
There are situations when only live tests can give more info on the device vitals. If you plan to test equipment while the power supply is active, consider safety a top priority. That way, you can protect everyone involved in the approved ongoing testing efforts. And if you need help with electrical wiring, don’t hesitate to contact Cloom. We have years of experience and can meet any requests your facility needs!