Juniper Networks MX240 Site Electrical Wiring Guidelines, Distance Limitations for Signaling

MX240 Ethernet Services Router Hardware Guide

NOTE: In North America, AC power cords must not exceed 4.5 m (approximately

14.75ft) in length, to comply with National Electrical Code (NEC) Sections 400-8 (NFPA 75, 5-2.2) and 210-52, and Canadian Electrical Code (CEC) Section 4-010(3). The cords supplied with the router are in compliance.

WARNING: The router is pluggable type A equipment installed in a restricted-access location. It has a separate protective earthing terminal (sized for UNC 1/4-20 ground lugs) provided on the chassis in addition to the grounding pin of the power supply cord. This separate protective earthing terminal must be permanently connected to earth.

CAUTION: Power cords and cables must not block access to router components or drape where people could trip on them.

For information about the AC power supply, including a description of components, see “AC Power Supply” on page 21. For instructions on connecting the power cord and grounding cable during initial installation, see “Connecting Power to an AC-Powered Router” on page 54. For instructions on replacing the AC power cord, see “Replacing an AC Power Cord” on page 118.

Site Electrical Wiring Guidelines

When planning the electrical wiring at your site, consider the factors discussed in the following sections.

Distance Limitations for Signaling

Improperly installed wires can emit radio interference. In addition, the potential for damage from lightning strikes increases if wires exceed recommended distances, or if wires pass between buildings. The electromagnetic pulse (EMP) caused by lightning can damage unshielded conductors and destroy electronic devices. If your site has previously experienced such problems, you might want to consult experts in electrical surge suppression and shielding.

Radio Frequency Interference

You can reduce or eliminate the emission of radio frequency interference (RFI) from your site wiring by using 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, you might want to seek expert

176■ Site Electrical Wiring Guidelines