UFC 3-560-01
6 December 2006
Including change 1, 7 December 2006
5-5.5
Insulator Testers. Use insulator testers to measure the potential across
each insulator in a suspect string of cap and pin insulators. They can be used without
interrupting service.
5-5.6
Leakage-Current Monitors. The leakage current that can occur from
overcurrent conditions on insulated ladder and truck booms must be monitored for
worker safety. Leakage current flows along the surface of tools or equipment due to the
properties of the device's surface and surface deposits. The permissible leakage
current on aerial lifts is one microampere per kilovolt ac or 0.5 microamperes per kilovolt
dc. Adverse weather conditions derate the normal dielectric quality of air which results
in a greater leakage current. Periodic testing is required. The use of a monitor on an
aerial lift providing a continuous display of leakage current is recommended. The
monitor should sound an alarm at a pre-set leakage current level to alert workers to
danger.
5-5.7
audible warnings of explosive atmospheres and/or low oxygen levels which often occur
in confined spaces. A continuous reading is given of any gas concentration ranging
from 0 to 100 percent of the lower explosive level (LEL) and 0 to 25 percent of the
oxygen level. A detector can be used to check battery rooms where ventilation is
suspect. Determine if a hazardous atmosphere exists before entering a confined space.
Hazardous atmospheres include: a contaminant concentration 10 percent or more of its
lower flammability limit; oxygen concentration less than 19.5 percent by volume;
contaminant concentrations exceeding specific OSHA standards (lead, asbestos,
cadmium, and like substances); and oxygen concentration more than 23 percent by
volume, particularly if oil mist or other combustible materials are present.
5-11
Previous Page
