If not designed and installed properly, wiring inside cable trays may pose hazards such as fire, electric shock, and arc-flash blast events. Below, we analyze the common cable tray safety hazards and discuss how each risk can be mitigated to ensure optimal safety and functionality. Low voltage electrical systems in construction still present significant hazards. This guide outlines essential safety precautions for. A generic guideline provided by The Cable Tray Institute indicates that cable trays should not be filled in excess of 40-50% of the inside area of the tray or of the maximum weight based on the cable tray specifications.
[pdf] Direct detection is the simplest form of optical signal recovery. The transmitter modulates the intensity of the optical carrier, and the receiver uses a photodetector (PIN diode or avalanche photodiode) that responds only to the optical power envelope. 100 Gb/s links (and higher) are now common between regional data centers, often stretching tens of kilometers. The receiver implements strong dispersion and delay lines on a compact chip. For much of the past fifteen years, the boundary between these two approaches was relatively clear.
[pdf] 
