Product defects include errors and omissions in design, construction/manufacturing, labeling, and assembly.
POWER LINE CONSTRUCTION
Each State adopts standards for power line construction that coalesce past experiences to encourage the construction of hazard-free systems. In California, the standard is called General Order 95 (or usually G.O. 95) for overhead lines. Hawaii uses the identical language and calls it G.O. 6. The standards can differ among the States.
These criteria attempt to identify different construction, maintenance, and uses of the system, as well as the activities that may occur under, around and above, and suggest assembly practices that will eliminate or minimize the opportunity for fires or shocks.
Machinery, equipment, and vehicles continually include more computers for finer control of motion, greater efficiency of operation, and less pollution. Indeed it seems that effective competition almost requires some form of computerization. In designer’s digital zeal they sometimes use the same central processing unit (CPU) for operation and control as they do for alarm monitoring and fail safe shutdown. When the control computer console is physically remote from the operating machinery it is also tempting to use one fiber cable to transmit both operating and safety signals.
Sometimes, without being a digital designer, it is easy to declare a design defect when a fiber modem, or a CPU fails, thereby disabling the emergency shutdown and allowing a fire or other destructive damage. It merely requires pointing out that proper basic design requires the safety shutdown mechanisms should operate independently from the main controls.
Although the forensic engineer must have a working familiarity with many appliances, often again identifying a defect only requires a common sense level of understanding. For example, using plastic for the over-temperature linkage of a toaster can result in a fire when the linkage melts before turning off the toaster.
Computerization allows sophisticated control of convenience and comfort as well as resource conservation from enhanced efficiency of operation. The forensic engineer must be able to include control system practices such as critical damping, oscillation, and feedback when investigating an accident or failure.
DEFECTS & THE LAW
Two types of warning may be required and tested for:
• Adequately instruct as to how the product is used,
• Warn of potential risks or side effects.
The first is to reduce risks, the second is to provide an informed choice.
See my case study about defective labels.
Fire Cause and Origin
Power Wiring and Circuits
National Electrical Code (NEC)
General Order 95
Electrician Trade Practice
Lock Out / Tag Out
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