Vehicle Electrical Failures and Fires

March 2011

I. Introduction

NYMIR subscribers have experienced high-severity

fire losses in the past several years that were the

result of vehicle electrical failures. These fires have

destroyed structures, vehicles and other equipment.

In each case, these incidents caused substantial

damage, great inconvenience and loss of productivity

to the municipal employees who were charged with

recovery and continuity. Because of the technical

nature of this Bulletin, we recommend that

subscribers speak to the vehicle manufacturer or

repair company.

II. Causes

These fires have started as a result of the vehicle’s electrical system short circuiting due to worn electrical wiring insulation, exposed bare wire or cable. Once the cable is worn (typically on the cable running from the batteries to the starter) and there is contact with metal, a circuit forms and heat is generated. The heat generated in a small physical area and the availability of fuel (cable insulation, hydraulic fluid, oil, etc.) ignites the fire. Once these fires start, rapid fire usually spreads inside the structure resulting in substantial damage to the building and other vehicles housed in the area.

Photo I: Damage from a Highway Garage Fire from Electrical Failure

HANDBOOK Automobile

SPRING HAZARDS

When placing plows into storage, carefully inspect hooks and chains which suspend the salt boxes and

sanders for stretching, corrosion and wear. Replace any worn components.

Inspect municipal signs for damage and lack of reflectivity.

Inspect fences for damage from snow plowing.

Inspect parking lots for pot holes, damaged drainage grates and other

uneven surfaces.

Inspect curbs and sidewalks for uneven or damaged surfaces.

III. Preventive Measures

Some immediate preventive measures DPW and Highway personnel can take to prevent these fires include:

� Inspect battery cables and vehicle electrical distribution wiring for signs of wear, chaffing or frame contact and secure as necessary to prevent cable abrasion.

� Check all electrical connections to ensure they are tight and corrosion free. � Inspect the vehicle fuse box against the owners’ manual to ensure proper fusing of

circuits and secondary equipment. Ensure the proper fuse amperage is in the appropriate socket. Fuse protection should include fail safe protection from incidents of a main electrical cable short or failure. If one circuit seems to be failing (blown fuses) frequently, there is something wrong with the circuit; most likely a short. Do not replace a blown fuse with one of higher amperage. Consult with authorized vehicle manufacturer service personnel as necessary for guidance.

� Follow manufacturer recommendations for the proper installation (including recommended wire gauge), operation of the vehicle electrical system components and all aftermarket equipment requiring electrical connection to vehicle systems. If the installation is being done in-house, use wire loom (or similar protection) to guard wiring against insulation wear – wires may contact metal parts.

� Inspect fuel and hydraulic lines for signs of wear. Repair and secure as necessary to prevent frame abrasion. Clean up oil and grease buildup frequently to reduce this as a fuel source; cleaning will also assist in thorough and efficient inspections.

� Battery charging cables must be of proper gauge for the amperage of the charger and system. These cables must be in good condition and connected properly to the positive terminals and ground.

Photo II: Arrow Points to Worn Cable Insulation from Frame Rub

IV. Research Findings, Vehicles at Risk and Potential Solution

Research has shown the vehicles involved in these fires have been manufactured in 2007 or earlier. These vehicles are not equipped with a positive disconnect between the batteries and the starter. Even when the vehicle is shut off, this circuit remains energized.

One remedy available to aid in preventing these fires is to install a power disconnect on vehicles that do not disconnect power between the battery and starter when the vehicle is turned off. Disconnect switches which disable this power comes standard on most new vehicles. This is a feature that Subscribers must specify on new vehicle orders in

order to further reduce the potential for future losses. These devices can be installed on existing older vehicles without switches. Several manufacturer representatives report these switches will not interfere with the minute amount of power that energizes the vehicle’s computer. The costs for these disconnect switches ranges from $150 to $300 installed.

Another remedy is to look at the location of the battery box in relation to plow equipment. Some DPW and Highway Departments have moved the battery box to a different location on the vehicle due to the location of the plow equipment. This has reduced the potential for the cables to rub by relocating the battery box to a position that is better protected with less potential for cable wear.

V. Other Fire Safety Considerations/Reminders

Here are other items to check which can reduce your overall fire exposure in the garage. These include:

� Maintain good housekeeping practices and combustible material storage. Prevent the accumulation of combustible materials. Refuse must be removed regularly.

� Fire doors that are to be closed must remain closed. Inspect fire doors held open by fusible links and magnetic hold opens to ensure these devices are operating properly and the closing pathway is not blocked or compromised. Fusible links should not be painted over.

� Seal all wall penetrations with hydraulic cement or “Fire Stop”. � Check the condition of building electrical systems – check for missing circuit

breakers. If there are open circuit breaker spaces, protect them with an appropriate protective cover. Maintain 36 inches of clearance in front and to the side of all electrical panels. Repair any defects identified.

� Have the fire alarm company inspect fire alarm systems.

Consider the installation of a monitored fire alarm system. If the DPW or Highway Garage is in an isolated location (away from main roadways/streets; more than 5 miles from the closest fire department; on low traffic volume roadways/streets) serious consideration should be given to installing a monitored fire alarm system.

VI. Newer Diesel Vehicles and Potential Fire Hazards

Beginning in the 2008 model year, all commercial diesel vehicles placed in service in the United States had to be equipped with a Diesel Particulate Filter (DPF) to reduce emissions and enable the vehicle to use low grade sulfur diesel fuel. The DPF introduces the potential for a vehicle fire due to the amount of heat that is generated during its operation.

When clogged, the DPF requires cleaning. This is sensed by the vehicle’s computer. When the DPF must be cleaned, the vehicle goes into a regeneration mode. During this mode, the DPF undergoes catalytic cleaning that generates extremely high heat. In vehicles manufactured in the 2008 to 2010 model years, diesel fuel, injected by a separate injector from the fuel pump is pumped into the DPF and the catalytic reaction occurs. During DPF regeneration, temperatures between 2,000 and 3,000 degrees Fahrenheit are

achieved inside the DPF. If the vehicle is parked in an enclosed area, near combustibles or in a grassy field, fires may and have occurred – none recorded by NYMIR.

Vehicle manufacturers recommend that vehicles undergoing regeneration not be parked and to keep them moving on the roadway. This decreases the regeneration time. As a safeguard, if your vehicle has undergone regeneration and you return to the shop shortly afterwards, it is a good idea to allow the vehicle to sit outside for 15 to 20 minutes to allow the radiant heat from the DPF to dissipate.

Beginning in the 2011 Model year, the DPF systems have been converted to use Urea in place of diesel fuel to accomplish the regeneration process. The heat generated from these regenerations is still significant; in excess of 1,000 degrees Fahrenheit and the same precautions need to be undertaken.

Another problem has arisen with the Urea systems on smaller vehicles (diesel pickups and one ton vehicles). The Urea tanks are in isolated locations on the vehicle and most are not heated. Urea freezes around 15 degrees Fahrenheit. Once frozen, the vehicle computer gets scrambled and the regeneration cycle is disrupted. If you are going to replace smaller diesel vehicles, make certain you specify a tank heater on the Urea tank.

Photo III: Arrow Points to Location of DPF on 2010 Mack 10-Wheeler

VII. Conclusion

Subscribers would be crippled by a catastrophic fire and loss of their fleet all at one time. Vehicle electrical system maintenance must be high on the list of fleet maintenance and safety items that receive regular attention.