Installing strobe lights for overhead bridge cranes at Jervis Webb
Harbor Springs Michigan
Last week I got a call from Jervis Webb to trouble shoot the strobe lights that one of their workers installed on all six of the bridge cranes that are used throughout the plant. When working in factories you have to be very careful of what voltages you are working with and connecting to. They usually use 480 volts for large stationary equipment like: presses, mills, drills, welders, cranes and some lighting. This high voltage is very efficient but also hazardous. So for the control of these large machines and general use receptacles the voltage is dropped down to 120 volts (which is the same as house hold voltage). This is much safer for the workers coming in direct contact with the controls.
Because of this an electrician or maintenance person has to be constantly aware of the system he is woring on and the voltage rating of the device he is connecting. As soon as I opened the control box I noticed that the strobe light was connected to the high voltage side and that the strobe was only rated for 120 volts. This caused catastrophic failure of the strobe light as you can see by the picture. So after new lights where ordered I rewired them into the low voltage control side of the control box using auxilliary contact blocks that snap onto the existing contactors.
Now whenever the bridge is in motion the stobe lights go off as a warning for workers to watch out for large pieces of material and equipment in motion.
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