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EX9253 Site Guidelines and Requirements

Environmental Requirements and Specifications for an EX9253 Switch

The switch must be installed in a rack or cabinet housed in a dry, clean, well-ventilated, and temperature-controlled environment.

Ensure that these environmental guidelines are followed:

  • The site must be as dust-free as possible, because dust can clog air intake vents and filters, reducing the efficiency of the switch cooling system.

  • Maintain ambient airflow for normal switch operation. If the airflow is blocked or restricted, or if the intake air is too warm, the switch might overheat, leading to the switch temperature monitor shutting down the switch to protect the hardware components.

Table 1 provides the required environmental conditions for normal switch operation.

Table 1: EX9253 Switch Environmental Tolerances




No performance degradation up to 10,000  ft (3048  m)

Relative humidity

Normal operation ensured in relative humidity range of 5% through 90%, noncondensing


Normal operation ensured in temperature range of 32° F  (0° C) through 104° F  (40°C)

Nonoperating storage temperature in shipping container: – 40° F  (–40°C) through 158° F  (70°C)


Designed to meet Telcordia Technologies Zone 4 earthquake requirements

Maximum thermal output (500  W)

1705  BTU/hour


Install EX  Series switches only in restricted areas, such as dedicated equipment rooms and equipment closets, in accordance with Articles 110– 16, 110– 17, and 110– 18 of the National Electrical Code, ANSI/NFPA 70.

General Site Guidelines

Efficient device operation requires proper site planning and maintenance and proper layout of the equipment, rack or cabinet, and wiring closet.

To plan and create an acceptable operating environment for your device and prevent environmentally caused equipment failures:

  • Keep the area around the chassis free from dust and conductive material, such as metal flakes.

  • Follow prescribed airflow guidelines to ensure that the cooling system functions properly and that exhaust from other equipment does not blow into the intake vents of the device.

  • Follow the prescribed electrostatic discharge (ESD) prevention procedures to prevent damaging the equipment. Static discharge can cause components to fail completely or intermittently over time.

  • Install the device in a secure area, so that only authorized personnel can access the device.

Site Electrical Wiring Guidelines

Table 2 describes the factors you must consider while planning the electrical wiring at your site.


You must provide a properly grounded and shielded environment and use electrical surge-suppression devices.

Avertissement Vous devez établir un environnement protégé et convenablement mis à la terre et utiliser des dispositifs de parasurtension.

Table 2: Site Electrical Wiring Guidelines

Site Wiring Factor


Signaling limitations

If your site experiences any of the following problems, consult experts in electrical surge suppression and shielding:

  • Improperly installed wires cause radio frequency interference (RFI).

  • Damage from lightning strikes occurs when wires exceed recommended distances or pass between buildings.

  • Electromagnetic pulses (EMPs) caused by lightning damage unshielded conductors and electronic devices.

Radio frequency interference

To reduce or eliminate RFI from your site wiring, do the following:

  • Use a twisted-pair cable with a good distribution of grounding conductors.

  • If you must exceed the recommended distances, use a high-quality twisted-pair cable with one ground conductor for each data signal, when applicable.

Electromagnetic compatibility

If your site is susceptible to problems with electromagnetic compatibility (EMC), particularly from lightning or radio transmitters, seek expert advice.

Some of the problems caused by strong sources of electromagnetic interference (EMI) are:

  • Destruction of the signal drivers and receivers in the device

  • Electrical hazards as a result of power surges conducted over the lines into the equipment

Clearance Requirements for Airflow and Hardware Maintenance for an EX9253 Switch

When planning the site for installing an EX9253 switch, you must allow sufficient clearance around the switch.

  • For the cooling system to function properly, the airflow around the chassis must be unrestricted. Allow at least 6  in. (15.2  cm) of clearance between side-cooled switches. Allow 2.8  in. (7.1 cm) between the side of the chassis and any non-heat-producing surface such as a wall. See Figure 1.

  • If you are mounting the switch on a rack or cabinet along with other equipment, ensure that the exhaust from other equipment does not blow into the intake vents of the chassis.

    Airflow must always be from front-to-back with respect to the rack. The switch must not interfere with the cooling of other systems in the rack. Fillers must be used as appropriate in the rack to ensure there is no recirculation of heated exhaust air back to the front of the rack. Care must also be taken around cables to ensure that no leakage of air in situations where recirculation may result.

  • To accommodate power cable bend radius at the rear of the chassis and the interface cable bend radius at the front of the chassis, provide at least 2.75  in. (7  cm) at the rear and 3.5  in. (8.9 cm) at the front.

  • For service personnel to remove and install hardware components, there must be adequate space at the front and back of the switch. At least 24  in. (61  cm) is required both in front of and behind the switch. NEBS GR-63 recommends that you allow at least 30  in. (76.2  cm) in front of the rack and 24  in. (61.0 cm) behind the rack.

    Figure 1 shows the clearance requirement for an EX9253 switch chassis.

    Figure 1: Clearance Requirements for Airflow and Hardware Maintenance for an EX9253 Switch ChassisClearance Requirements for Airflow and Hardware Maintenance for an EX9253 Switch Chassis

Rack and Cabinet Requirements for EX9253 Switches

You can mount an EX9253 switch on four-posts of a 19-in rack or in a cabinet that contains a 19-in. rack.

Rack requirements consist of:

  • Rack type

  • Mounting bracket hole spacing

  • Rack size and strength

  • Rack connection to the building structure

Table 3 provides the rack requirements and specifications.

Table 3: Rack Requirements and Specifications

Rack Requirement


Rack type

You can mount the device on a rack that provides bracket holes or hole patterns spaced at 1  U (1.75  in. or 4.45  cm) increments and meets the size and strength requirements to support the weight.

A U is the standard rack unit defined by the Electronic Components Industry Association (

Mounting bracket hole spacing

The holes in the mounting brackets are spaced at 1  U (1.75 in. or 4.45 cm), so that the device can be mounted in any rack that provides holes spaced at that distance.

Rack size and strength

  • Ensure that the rack complies with the size and strength standards of a 19-in. rack as defined by the Electronic Components Industry Association (

  • Ensure that the rack rails are spaced widely enough to accommodate the external dimensions of the device chassis. The outer edges of the front-mounting brackets extend the width of the chassis to 19 in. (48.2 cm).

  • The rack must be strong enough to support the weight of the device.

  • Ensure that the spacing of rails and adjacent racks provides for proper clearance around the device and rack.

Rack connection to building structure

  • Secure the rack to the building structure.

  • If earthquakes are a possibility in your geographical area, secure the rack to the floor.

  • Secure the rack to the ceiling brackets as well as wall or floor brackets for maximum stability.

Cabinet requirements consist of:

  • Cabinet size

  • Clearance requirements

  • Cabinet airflow requirements

Table 4 provides the cabinet requirements and specifications.

Table 4: Cabinet Requirements and Specifications

Cabinet Requirement


Cabinet size

  • You can mount the device in a cabinet that contains a 19-in. rack as defined by the Electronic Components Industry Association (

  • The minimum cabinet size must be able to accommodate the maximum external dimensions of the device.

Cabinet clearance

The minimum total clearance inside the cabinet is 30 in. (76.2 cm) between the inside of the front door and the inside of the rear door.

Cabinet airflow requirements

When you mount the device in a cabinet, ensure that ventilation through the cabinet is sufficient to prevent overheating.

  • Ensure adequate cool air supply to dissipate the thermal output of the device or devices.

  • Ensure that the hot air exhaust of the chassis exits the cabinet without recirculating into the device. An open cabinet (without a top or doors) that employs hot air exhaust extraction from the top ensures the best airflow through the chassis. If the cabinet contains a top or doors, perforations in these elements assist with removing the hot air exhaust.

  • Install the device in the cabinet in a way that maximizes the open space on the side of the chassis that has the hot air exhaust.

  • Route and dress all cables to minimize the blockage of airflow to and from the chassis.

  • Ensure that the spacing of rails and adjacent cabinets is such that there is proper clearance around the device and cabinet.

  • A cabinet larger than the minimum required provides better airflow and reduces the chance of overheating.