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With Great Power: Misuse of Electrical Equipment

July 16, 2022

People find unique ways of modifying the electrical system or devices in their homes, which are not always correct or safe. According to the NFPA, there are approximately 46,000 electrical fires each year. Additionally, electrical failure or malfunction caused an average of 390 civilian deaths, 13,130 civilian injuries, and US$1.5 billion in direct property damage between 2015 and 2019.

Figure 1: An illustration of the frequency and severity of electrical fires.

Examples of misuse

Misuse of electrical equipment can take many forms. It can be installing an electric heater in an enclosed area without proper combustible clearance or grounding a plastic-coated gas line (figure 2).

Figure 2: An improperly grounded gas line

Another example of misuse is a contractor leaving energized lights in an attic space and then blowing cellulose insulation all around it. One flick of a light switch can cause a fire. Misuse can occur when people cut corners. In figure 3, the armoured cables are stripped and connected at the outlet and not within the fixture box.

Figure 3: Improperly connected cables.

Misuse can occur when people have enough knowledge to produce a result, but not enough to understand the risks.

Figure 4: Use of jumper cables (left) and screwdrivers (right) to steal power from the meter base on the exterior of the home.

Misuse may also be from an electrician leaving an exposed, live, unkempt cable in the attic space, as shown below:

Figure 5: Exposed wiring that led to a fire.

The electrician discontinued a branch circuit inside a residential home for this file. The branch circuit was left energized, resulting in a fire. The cable was left in the attic and not kept with a twist-on connector.

Misuse and fatalities

Data collected by the Electrical Safety Authority (ESA) in the last 10 years shows that 30% of electrical-related fatalities occurred from human error. Misuse, misadventure, and theft accounted for 15% of these fatalities.

Figure 6: Percentage of non-occupational electrical-related fatalities by activity type in Ontario (2011-2022).

The categories in the table are specified by major contributing factors, which does not rule out other factors within each column. Improper use ties to the second-highest percentage of all the identified causes in figure 6. There may also be more misuse under different categories, such as unknown human error and improper installation.


The most improperly used appliances are ranges. Data collected by the ESA for causes of stovetop fires in the last five years found that a large number of the fires were caused by different variations of improper use. The largest of these was unattended cooking fires.

Figure 7: An illustration of the misuse of ranges.

Other causes of misuse included children playing, nearby combustibles, improper handling, storage and discarding, and accidentally igniting an inadvertent item.

Misuse of ranges: Case study 1

Figure 8: The incident scene after a fire caused by a range.

People often use ranges as temporary or permanent tables. One such case resulted in the ignition of a spice rack left on an element of the electric range. The tenant energized the wrong element, which ignited the spice rack and resulted in the damage shown in figure 8.

Misuse of ranges: Case study 2

Figure 9: The burned cooktop.

We were called to investigate a fire that originated in the kitchen. We were informed that the homeowner was at a soccer game when the fire happened and that no one had used the range for a while. Unfortunately, the contractor modified the scene before we arrived, and materials had been removed from the scene. However, our examination of the scene revealed that the fire had originated from the surface top of the electric range.

Figure 10: The yellow circle shows the residue of a plastic box found around the house.

We found a bin similar to the green plastic that adhered to the range. We determined that the homeowner placed a plastic box on the surface top, intending to put it away and bumped the controls into the “on” position. Then, they rushed out of the home midway.

Figure 11: The plastic box that activated the cooktop.

We later found out that the contractors moved the green plastic bin before our arrival. Instruct contractors to hold off on modifying the room of origin until a forensic engineer arrives. For all cases, we recommend leaving the scene intact.

Commercial overload and overcurrent

Other possible causes of misuse-related electrical failures can be too much current or damaging the cables. One such way involves overload, which is the operation of the equipment or wiring above its normal rating, possibly creating ignition.

Figure 12: An extreme example of overload in a commercial office building (left) and a current overload test conducted in our lab (right).

Misuse can result in overcurrent, which is the condition wherein more current flows in a conductor than is allowed by the accepted safety standards. Current overload in our lab test caused the cable to overheat and ignite the insulation surrounding it (figure 12).

Figure 13: Industrial equipment that suffered overload.

In one case, a building designed for light commercial use was repurposed for heavy commercial use by a new occupant. This resulted in more significant electrical current usage on the system. Consequently, a fire occurred within the building’s electrical system.

Misuse of equipment: Case study 1

Equipment should always be operated and maintained as specified by the manufacturer.

Figure 14: Failure of an 11-year-old variable frequency drive (VFD) in a water pumping station.

A VFD is used to control alternating current, motor speed, and torque. In this case, collected information determined that this pumping station was not the main one. We discovered that the pumping station had been utilized more frequently two months before the fire.

Figure 15: The damaged VFD cabinets.

At the time of the fire, the VFD was under a load greater than it was manufactured for, and the main breaker tripped. Our onsite investigation determined that the fire originated from a control panel in one of the VFD’s control cabinets on the south side of the building.

Further information provided determined that the VFD had yet to have any maintenance completed. This included thermal imaging to identify loose connections. Therefore, the combination of stressing the VFD under a greater-than-normal load and not completing any maintenance resulted in the device’s failure and caused the fire.

Misuse of equipment: Case study 2

Figure 16: The damaged digestive blower.

A fire occurred in a digestive blower at a water treatment facility. When we arrived for the investigation, the equipment from the blower had already been removed and modified, which made the investigation much more difficult. The internal components had all been removed from the equipment.

Maintenance had been completed recently, but incorrectly. We were informed that the 12-year-old blower had been operating under a larger-than-normal load, as sewage had been rerouted to this blower to accommodate the failure of another. The combination of this and the above-average sustained load resulted in the failure of the equipment.

To avoid such incidents, equipment must be operated as specified by the manufacturer, be well-maintained, and have a usage record. In our case, we received 12 years’ worth of usage and maintenance records, which was essential in determining the cause.

Transformers and lighting

We have seen cases where transformers exploded, or commercial LED lighting failed when older models were replaced with newer ones.

Figure 17: Exploding transformers.

Electricity in the power distribution center (figure 17) is passed through, modified, and distributed to other areas. In this case, we discovered that a company had newly installed several transformers, all of which exploded.

Our investigation revealed that the new models were installed without properly assessing the old system. The new transformers need to be adequately rated for the electrical system and thus were incompatible. This resulted in noise polluting the source, which resulted in overheating in the transformers.

The issue was rectified once the transformer was replaced with adequately rated equipment. There are certain regulations to prevent the problems like this. In Ontario, transformers over 1000 volts need to be properly rated and sized, and the plans need to be renewed with the ESA. This file was a great subrogation opportunity, as the installer should have been aware of the regulations and ratings.

A similar issue can occur when newer lighting needs to be properly rated and installed into an electrical system.

Figure 18: Newer lighting (left) and an illustration of venting, indicated by yellow arrows (right).

Capacitors on the circuit boards of such lighting fixtures may draw excessive current and vent. In these cases, it is essential to leave the evidence untouched and get a forensic investigator to go through all the evidence with a fine-toothed comb.

When it comes to a fire or failure that may involve some form of electrical component in residential and commercial buildings, attempt to keep the electrical panels intact. Removing or modifying the panels before we arrive will likely eliminate evidence that can be crucial to our investigation.

If power needs to be reintroduced before we can arrive, speak to the contractor or electrician and have them take detailed photos of the panel and wiring before they modify anything. This way, we retain the evidence.


One regular cause of residential electrical fires comes from damaged cables. A typical single-family dwelling has 1500 feet of wiring and 200 feet of extension cords. This culminates in approximately 1700 feet of possible failures.

Extension cords

Electrical wiring and extension cords can be sources of fire. The Ontario Electrical Safety Code defines extension cords as flexible with certain criteria and uses. In most cases, the manufacturer will indicate some criteria on the cable itself and the packaging.

Not all chords are the same. Some can be used in indoor settings, whereas others can be used only in outdoor settings. Similarly, their load capacity differs. As such, you must be very mindful of all the information on extension cords because it comes in handy for insurance adjusters.

Figure 19: Examples of cord labels with manufacturer specifications for their operation criteria.

Be mindful of the labels on extension cords. A certification symbol is stamped onto their packaging when cords are properly certified and tested. There are instances where the approval sign could be counterfeit. As forensic engineers, we could do the proper research for you to find out this information.

Figure 20: Overloaded extension cords.

Testing and certification of chords are done in free air. During testing, cords are allowed to heat up to a certain point. The cord on the left (figure 20) passes through a crevice, which could pinch the cord and create more heat. Piling cords together, as shown in the two other pictures in figure 20, can result in overheating and possibly overloading with all the appliances plugged in. In a lot of cases, overheating could be the result of overcurrent and overloading.

So, try as best as possible to leave the scene undisturbed and extension cords in situ. This could be especially relevant in situations where you have tenants. It could help us determine if there is subrogation potential if the tenant is insured. You will be best positioned for subrogation if you leave everything as undisturbed as possible for the forensic engineer or fire investigator to examine and analyze.

Another common example of misuse is using your two prongs and leaving the ground pin unplugged.

Figure 21: An unplugged ground pin.

Grounding of any electrical equipment provides a path for instances where there’s an electrical fault trying to find a path to the ground and back to the source. This is often because of the type of extension cords used. If you have no path, the electrical current trying to find the path could take any other conductive surface as its path. This could create a shock and, in some cases, a fire hazard.

Figure 22: An extension cord hardwired into a junction box.

Removing a plug and hardwiring an extension cord into a junction box is another example of misuse. Extension cords are not intended for permanent wiring. This type of flexible cord is specifically for temporary wiring. Therefore, hardwiring could cause overcurrent, overloading, and overheating, resulting in a fire.

Case study

Figure 23: The property where the incident occurred.

The loss occurred in an older home, which is not atypical. Older homes often only have a few receptacles. In these situations, many people buy extension cords, and in some cases, daisy chain extension cords, to have more outlets.

In this case, a baseboard heater was broken, and the homeowner purchased a portable one to heat the bedroom. They used an existing extension cord, and it resulted in a fire. Unfortunately, the homeowner succumbed to her injuries.

Figure 24: What was left of the extension cord.

Further examination revealed that the extension cord was not rated for use and was already damaged. Therefore, it overheated and ignited surrounding fuels and combustibles, resulting in a fatality.

Lichtenberg generators

Figure 25: Fractal wood art (left) that is created using a high-voltage device (center and right).

Lichtenberg generators have become another common misuse candidate. The high-voltage device used for fractal art is typically connected by clamps to nails on a surface. A chemical solution is then used to create a conductive path for the current.

Misuse happens when people use this essential burning machine by dismantling a microwave, for example. They remove a high-voltage transformer from an old microwave and as a result, expose componants that are a fire hazard. This type of misuse has led to several fatalities.

In many cases, people often learn how to do something like this from a video online. This raises the question of who is at fault when a loss inevitably occurs. In one of these fatalities, a police investigation identified that the individual who suffered from shock and electrocution was watching videos of the same influencer to create the device. Whether you can subrogate against an influencer remains to be determined.

Manual motor controllers (MMCs)

Figure 26: MMCs certified for disconnecting means.

Manual motor controllers are typically used in commercial settings. They are used as a switch for a motor, system, and possibly a whole commercial line of products. These controllers are essentially switched with a much larger load.

People have started using an MMC as a disconnecting means. The Ontario Electrical Safety Code defines a disconnecting means as something certified and approved to be used as a disconnect, such that you can maintain equipment downstream and remove and replace the equipment. Many MMCs are not manufactured for that unless otherwise specified on the product.

When an MMC is certified to disconnect, it has been tested to ensure that you cannot have energy going downstream when you disconnect this switch. Unfortunately, people have used the ones without a disclaimer, resulting in several fatalities.

MMCs: Case study

A maintenance worker intended to maintain and replace a pump motor when he found it not functioning properly. He used a manual motor controller to disconnect. The contacts of the line side of the motor disconnect were welded shut, so energy remained in the pump motor. The worker began his maintenance without testing for energization and got electrocuted.

There was a coroner’s inquest as a result of this fatality. And now added to the newest version of the Ontario Electrical Safety Code is a new code rule that states: “A manually operated across-the-line type of motor starter that is not marked ‘suitable for motor disconnect’ shall not be used as a disconnecting means and shall be field marked.” Such markings include:

  • Warning: Do not use it to disconnect the motor.
  • Indication of the disconnecting means and its location

As investigators, we look for these field markings, especially in this environment. We know what to look for and which code rules apply to that.

Aluminum wiring and rated receptacles

Figure 27: Examples of aluminum wiring and receptacles.

Aluminum wiring was more commonly installed around 1965 to the late 1970s. It is less expensive compared to copper. However, there is a caution to be used when you are terminating them. Some scientific analysis would prove that the expansion rate for aluminum is greater than that of copper.

Suppose you are not using aluminum with the right terminations and connections. In that case, it can end up with loose connections and high-resistance spots. This can lead to a fire.

Dealing with aluminum wiring

A lot of the older cables that were used were rated for 60 and 75 degrees and may not be used for modern fixtures. The ESA has produced some solutions:

  • Ask the installers to take further action when replacing light fixtures, for example. This includes using 90 °C heat shrink to give some more insulation against failure.
  • Ensure that receptacles and other devices are rated for aluminum. These are typically marked “CO/ALR” or some variation indicating that the receptacle is approved for copper or aluminum wiring use.

Case study

Figure 28: The circuit found in the home during our investigation.

During further investigation, we identified aluminum wiring across the home. Aluminum wiring was connected to a receptacle that was not rated for this wiring. The wiring ignited the headboard and resulted in a fire.

There was over fusing, replacing an adequately rated fuse with a 15-amp fuse that was put in with a fuse rejecter. In old fuse panels, the fuse is a different size. The smaller fuses needed a rejecter to fit into the large (30 amp) socket.

In this case, the individual had fuses burning out. They removed the 15-amp fuse and the rejecter and replaced them with a 30-amp fuse, resulting in over-fuse in the circuit.