December 16, 2009

Premise Liability:The Trick is in the Codes
Appliance Fires: The Role of Reverse Polarity
Meet the Expert:  Thomas Baker, P.E. 

Premise Liability: The Trick is in the Codes

CED engineers are often retained as experts on injury producing premise liability accidents representing the plaintiff, defendant or an insurance company. A common assertion is that the surface or other hazard in the vicinity was the cause of the accident. To determine the cause of the accident, CED engineers inspect the accident scene, perform testing when appropriate and research standards and codes to determine causation.

When CED is retained, one of the initial tasks completed by the engineer is to perform a site inspection to document the area with photographs, measurements and testing as needed and/or appropriate. Once the accident scene has been documented by the inspection, the engineer will research codes and standards that apply to a particular case. CED has an extensive library of codes and standards that allow our engineers to research a case from several different angles. The code that was in effect at the time that the structure was first approved and/or modified is the first element in understanding the design requirements for the accident site. The following are a few of the codes that apply to premise liability accidents:

• Building Codes – These can be either International or Building Officials Code Administration (BOCA) codes that set requirements items such as handrails, treads,

risers and other construction details to help engineers determine if the structure or location was constructed in accordance with applicable codes.

•  American Disability Act (ADA) Related Codes – Codes such as American National Standards Institute (ANSI) that sets requirements for walking surface levelness in public and commercial spaces.

•  National Fire Protection Association (NFPA) – Codes such as, the Life Safety Code (NFPA 101) which discusses designs for exits and discharging of people from spaces.

•  American Society for Testing and Materials (ASTM) - Standards for the practice of safe walking surfaces such as wet surfaces, tile, wood and other surface materials.

•  Occupational Safety and Hazard Administration (OSHA) - Laws that discuss walking surface requirements and hazards.

CED experts use their advanced training, education and experience to research and document these codes. The engineer can then apply the appropriate codes to the accident in order to render a comprehensive opinion as to causation or contributing factors. This combination of inspection, testing, research and analysis provides both the jury and the client the insight and understanding as to what caused the accident. With a large library of standards and other advanced tools, CED engineers can provide in-depth analysis to accidents from the simple to the complex.

Appliance Fires: The Role of Reverse Polarity

Many times when a fire occurs, the investigator or Fire Marshal is quick to determine causation as a product defect; the search for the underlining cause of the fire then begins. A key factor in helping CED's engineers determine the cause of a fire has been understanding the wiring involved in the home or commercial product and the product's proper design. This brings us to the discussion of a topic called “Reverse Polarity,” and how reverse polarity and not an appliance can cause a fire.

Most house appliances in the United States use normal 110 AC power. The power cord for the appliance has either a three-prong plug or a two-prong plug where one plug is larger than the other. In a three-prong plug, the large cylinder prong is the ground, the left upper blade is neutral, and the upper right is energized or “Hot.” A three-prong plug can only be inserted into the wall outlet oneway; a deadly combination occurs when users remove the round ground prong and insert the resulting two-prong plug into the wall outlet in reverse. On a two-prong plug, the larger blade is normally neutral and the smaller blade is hot;

the large/small blade design can only be inserted into the wall outlet one way.

Reverse polarity can also result from an improperly wired wall outlet. If the hot and neutral leads are reversed at the outlet, then when a plug is properly inserted, the power to the appliance will have reversed polarity. This can occur if after wiring the outlet, the installer does not check the polarity of the outlet with a simple polarity plug that can be purchased at any hardware store.

Other examples of actions causing reverse polarity

•  Unauthorized modifications to a three prong plug.
•  Faulty wiring with an extension cord.
•  Unauthorized modifications to a two- prong plug to make it fit in reverse.

Does a product work if reverse polarity exists? The short answer is yes, but the plug configuration now bypasses safety mechanisms that would normally protect the product from potentially becoming dangerous. What is bypassed is the fuse in the appliance designed for the hot source is now on the neutral side; if a power surge travels to the outlet or product, the fuse can interrupt the electricity and protect the electrical components thereby avoiding the potential for a fire.

Warning Signs of Reverse Polarity

•  History of shocks from an appliance.
•  Failure of an appliance after only and few years.
•  Fire or burn patterns on the outlet, plug, surge protector or grounded chassis.
•  No sign of electricity when the circuit breaker is not tripped.

Meet the Expert:  Thomas Baker, P.E.

Thomas Baker, P.E., is one of CED's knowledgeable experts in Mechanical Engineering. Mr. Baker is able to bring his extensive manufacturing and product design experience to bear in his product liability cases. On his many premise liability cases he utilizes his Bachelor of Science degrees in Physics from Jacksonville University and Mechanical Engineering from Georgia Tech.

After graduation, Mr. Baker's work as a manufacturing engineer, contract field engineer, product engineer and engineering manager laid a solid foundation and breadth of knowledge which he brings to his work today. His work as a product development engineer for Hunter Fans is instrumental in his understanding of both the manufacturing process and the do's and don'ts of product design. This background also ensures that Mr. Baker is well versed in safety requirements, safety standards and safety practices in the operational and manufacturing workspace.

Mr. Baker is a certified engineer and has years of experience using the English XL Variable Incidence Tribometer for slip and fall investigations. He has examined “Slip & Fall” scenes in nearly every environment including: Docks, Cruise ships, Airports, Restaurants, Construction sites, Hotels, Shopping Malls and Private Residences. Code compliance, safety standards and industry practices are incorporated into each investigation.