• If system is exposed to abnormally low temperatures, allow a two hour warm up period, in ambient
temperature no lower than 32°F (0 °C) before turning on.
Failure to observe these guidelines may damage the chassis' internal components.
Humidity
High-humidity conditions may cause moisture to enter the system, and cause corrosion of internal components
and degradation of properties such as electrical resistance, thermal conductivity, physical strength, and size.
Extreme moisture buildup inside the system may result in electrical short circuit, which may cause serious
damage to the system. Each system is rated for storage and operation in 10 to 95 percent relative humidity,
non-condensing with a humidity gradation of 10 percent per hour. Buildings in which climate is controlled
by air-conditioning in the warmer months and by heat during the colder months usually maintain an acceptable
level of humidity for system equipment. However, if a system is located in an unusually humid location, a
dehumidifier should be used to maintain the humidity within an acceptable range.
Altitude
Operating a system at high altitude (low pressure) reduces the efficiency of forced and convection cooling
and may result in electrical problems related to arcing and corona effects. This condition may also cause sealed
components with internal pressure, such as electrolytic capacitors, to fail or perform at reduced efficiency.
Dust and Particles
Dust and other particles, if ingested, cause contaminant buildup in the system and increase the internal chassis
temperature. A clean operating environment can greatly reduce the negative effects of dust and other particles,
which act as insulators and interfere with the mechanical components in the system. The standards listed
below provide guidelines for acceptable working environments and acceptable levels of suspended particulate
matter:
• National Electrical Manufacturers Association (NEMA) Type 1
• International Electrotechnical Commission (IEC) IP-20
Air Quality
Dust is everywhere and often invisible to the naked eye. It consists of fine particles in the air that originate
from various sources, such as soil dust lifted by weather, from volcanic eruptions, or pollution. Dust at an
installation site may contain small amounts of textile, paper fibers, or minerals from outdoor soil. It may also
contain natural contaminants, such as chlorine from the marine environment and industrial contaminants such
as sulfur. Ionized dust and debris are dangerous and get attracted to electronic equipment.
The accumulation of dust and debris on electronic equipment has the following adverse effects:
• It increases the operating temperature of the equipment. According to the Arrhenius effect, an increase
in the operating temperature leads to a decrease in reliability and life of the equipment.
• The moisture and corrosive elements that are present in the dust can corrode the electronic or mechanical
components and cause premature board failure.
Cisco Catalyst 9200CX Compact Series Switches Hardware Installation Guide
13
Preparing for Installation
Humidity
