Friday, February 25, 2011

5 cents between sucess or disaster

A Simple 5 Cent Plastic Bushing
In Electrical Installations can make the difference
Between Life and Death?

Every day Electricians and Fire Alarm Technicians regularly violate a section of the NEC when they fail to put a simple 5 cent Plastic or older style Bakelite bushing or even pot metal bushing on the end of metallic pipe stubs
Which are feeding low voltage and High Voltage AC and DC devices.
The pipe stubs are typically used where low or high voltage plastic jacketed wires are brought down a wall and then when they get below 7 feet the NEC requires Physical Protection of the wires from damage and this is where the violation occurs. The wires as they enter the pipe are to be protected from abrasions by a simple plastic bushing fitting which either slips directly over the Metal pipe or Wiremold Type metal race way or an end fitting is installed and a bushing screws onto the fitting which provides the abrasion protection .But typically all to often the bushing is not placed on the pipe stub and this is where problems can begin .Building vibrations along with heat build up as high amperage equiptment is used especially in the case of higher voltage wires can cause the wiring to wiggle back and forth in the piping stub and In the case of a Fire Alarm System the wiring can become bruised and the jacket on the wire can be pierced and a Negative or Positive ground fault develops in the Fire Alarm System when the inner copper conductors make contact with the edge of the metal stub pipe .Which if not corrected can prevent a smoke detector or other fire device from properly operating and reporting a fire .This same ground fault condition can occur in the Bell /Horn /Strobe loop as well and could result in the sounder circuit not coming on and notifying which can result in serious injury or death and massive destruction of property. In the case of Higher voltage 120 or higher VAC wiring a ground can develop that does not trip the over current protection because it is slightly there or there is no grounded return path the metal stub is fastened to and an individual could receive a deadly electrical shock when they make contact between any metal surface and the pipe missing the bushing. Additionally a Fire can easily result when a hot conductor that gets scrapped or bruised at the end of the pipe creates an arc fault which fails to clear the protective device and heats the near by surfaces and a fire results.
Such a simple little fitting can cause this and many other problems in electrical systems because a simple 5 cent bushing was not used.
The answers why they are not used varies from tech thinking there not being needed because the wire seems loose in the pipe .To sheer greed in not spending the couple dollars in parts and labor it would take to properly do the job.
In any case many ground faults and electrical accidents and trouble shooting gremlin issues can be directly traced to a missing 5 cent plastic or Bakelite bushing.

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