Transformer maintenance involves several significant hazards. The most obvious of these are electrical risks and hazards, but it’s important to identify the other dangers personnel may encounter. Fire safety is one particularly pressing area to address, one that contractors may not immediately recognize as a relevant risk. Transformer fire risk assessments and other procedures are vital for safety.
Transformers present significant fire risks and hazards
The chief reason fire safety is crucial for transformer maintenance is that many units use mineral oil as an insulator. This cools internal components and minimizes electrical risks and hazards but also introduces combustion and flammability concerns.
Mineral oil has a flash point of 380 degrees Fahrenheit. While that’s relatively high, it’s far below the temperatures an electrical arc can create. Consequently, any electrical issues during maintenance can create explosions and fire if they reach this oil.
Oil-filled transformers must also be water-tight to keep this insulation inside. As a result, they provide the pressurized environment necessary for explosions to occur if that oil combusts. These incidents are uncommon — largely thanks to required fire protection — but they’re still possible and deserve attention.
Fire risks may go unnoticed
Another reason transformer fire risk assessments are so important is that they’re easy to overlook. Fire likely isn’t the first thing to come to mind when employees think of transformers. They’re usually focused on electrical risks and hazards, which are more obvious when dealing with high-voltage equipment.
Transformer fires are also highly unlikely in normal conditions, which can create a sense of complacency. However, this can lead to unsafe behavior, making these events more likely than they’d otherwise be. Human error aside, unpredictable conditions are always possible, so employees should follow every risk mitigation strategy available.
The more contractors forget about transformers’ fire risks, the more prominent these hazards become. Safety managers must prevent that through thorough safety training.
Maintenance personnel who follow appropriate safety guidelines can virtually eliminate fire-related incidents. Here’s how workers should manage these risks when servicing this equipment.
Minimize fire risks from the beginning
The first and most important step is to address fire hazards before maintenance is necessary. Contractors should include thorough fire prevention measures when installing new oil-filled transformers.
Fire walls are one of the most important of these protections. These barriers should extend 1 foot above and 2 feet beside the transformer. Where fire walls aren’t possible, technicians should clear all debris and flammable materials within 5 to 25 feet of the unit, depending on size. Water spray systems and drainage for spilled oil are also recommended.
Some transformers can last over 50 years before needing replacement, so the original installation may have occurred before these standards were in place. In those cases, businesses should install these protections around old units instead of only doing so with new ones.
Perform a transformer fire risk assessment
Fire risk assessments should be a standard part of transformer maintenance after installation. Before repairing this equipment, technicians should inspect it to gauge fire-related and electrical risks and hazards. That way, they can identify potential issues before beginning work.
Visual inspections are the first step in a proper fire risk assessment. Technicians should look for leaks, dents, rust and nearby flammable debris around the transformer.
Old or particularly sensitive equipment may also warrant an infrared scan to reveal if the inside is too hot. If nothing appears wrong, employees should still collect an oil sample once inside to test it for dissolved gas and similar contaminants.
Check the weather
Before beginning transformer maintenance, employees should also check local weather forecasts. Inclement weather makes fire hazards significantly more threatening, as lightning can strike pole-mounted transformers, wind can blow flammable debris in the way and dry air can make sparks more likely.
These situations may seem unlikely, but extreme weather is becoming more frequent as climate change worsens. To avoid unnecessarily hazardous conditions, technicians should only schedule maintenance for mild temperatures, low winds and no precipitation. If the weather starts changing mid-repair, consider delaying the fix for another, clearer day.
De-energize transformers before maintenance
Shutting off transformers is another crucial safety step. De-energizing equipment is a standard measure to prevent electrical hazards, and it affects fire safety, too. Minimizing these risks prevents sparks that could ignite the insulation oil.
Before working on the transformer, shut off its power and allow residual electricity to dissipate. Using a circuit tester to measure any remaining charge is also recommended, especially for high-voltage systems. Employees should avoid performing work until there’s no energy left in the system and not reconnect the transformer until they’re done.
Wear appropriate PPE
As with all OSHA-regulated tasks, transformer maintenance technicians should wear PPE to protect against electrical and fire hazards. This includes fireproof and nonconductive gloves, clothes and eye protection.
PPE like oxygen masks and fireproof coveralls may be necessary for some fire-related hazards but aren’t needed in transformer maintenance. While fires and explosions are possible, they’re rare enough that basic protections are sufficient. If workers follow all the above steps, the risk of combustion won’t be prominent enough to warrant anything more.
Check fire suppression systems
Maintenance personnel should include fire suppression system inspection in their regular repair routine. Incorporating these fire risk assessments into their larger workflow will ensure they always have reliable worst-case-scenario protection.
The National Fire Protection Association recommends these systems spray 0.25 gallons per minute for every square foot of transformer space. They should also be able to maintain that flow rate for at least an hour. To do that, all pipes, hoses and nozzles should be clear of debris and free of cracks.
Visual inspections of these systems can help identify mechanical flaws that may hinder their efficacy. Maintenance workers should also use sprinkler test valves to ensure sufficient water flow.
Transformer maintenance must consider fire hazards
Electrical hazards may be the most obvious threat in transformer maintenance, but fire risks deserve attention, too. Fires and explosions may be less common but are devastating when they occur. Employees who hope to stay safe must follow these steps to prevent and mitigate fire hazards during routine maintenance.
