Watch Those Connections!

Some appliances such as stoves and dryers, do not come with line cords when the appliances are purchased.  As a result, consumers have to make separate purchases in order to use their new machines.  When attaching the cords to the appliance, pay close attention to the way the manufacturer requires that the line cords are connected.  For many do-it-your-selfers, this is no big deal.  It shouldn’t be a big deal for a professional electrician either.  However, we are all human and subject to making mistakes.  Case-in-point: the following dryer fire.  Although minor as residential fires go, the damage could have been much worse.  The photographs shown below illustrate how the manufacturer called for the installation of the line cord and the subsequent way, the cord was connected.

The manufacturer’s schematic drawing shows how the “hot” (red and black wires) lines of the line cord were to be attached to the L1 and L2 terminal block terminals.  The common line or white wire was to be connected to the N terminal on the terminal block.  Lastly, the green wire or earth ground, was to be connected directly to the appliance housing.  The photograph below shows how the white and black wires were reversed on the terminal block.

 

 

Since the common and earth ground points are electrically the same point, the dryer was, in effect, energized through the housing.  Anything in contact with the dryer housing, such as the exhaust duct, will also become energized.  Dryer ventilation ducts are usually coils of steel wire wrapped with a thin layer of vinyl or aluminum material.  As current flows through the steel wire, the external covering is heated.  If not stopped, the heat will cause the covering to melt and possibly ignite.

Happy Holidays!

R.j. Hill Consulting would like to wish everyone a Happy Holiday Season.

Wheel Separation in 2016 Ford Taurus-Possible Recall?

One of our recent investigations involved the separation of the left front wheel and whether it was the cause of a two vehicle accident.  The scenario was such that the driver made a right hand turn and felt the vehicle pull to the left.  The driver also stated that he lost control and hit a parked car.  Typically, in these types of impacts, the wheel is pushed into the wheel well.  But, in this case the wheel separated from the car.  Upon examination, it was determined that the threaded connection holding the strut to the frame was broken as well as the clamping part of the lower steering knuckle.  The failed parts are shown below.

Failed strut threaded connection

Clamping part of lower steering knuckle found broken

It should be noted that the steering arm tie rod was also bent and broken and that a stabilizing rod connected to the strut was separated from its knuckle joint.  If either of these connections is broken, then the wheel will become unstable.  Are there other instances where drivers have experienced similar situations?  Is this a condition that warrants a recall?