Safety
This chapter provides safety information and guidelines for installing and maintaining Harris Stratex Networks (HSX) radio systems. Refer to:
Overview
This chapter covers the following topics:
Operator Safety
Ø Radio Frequency and Microwave Safety
Ø Electrical Hazards
Ø Chemical Hazards
Ø Laser and Fiber Optic Cable Hazards
Ø Hoisting and Rigging Safety
Ø General Site Safety
General Hazards
Ø Electrostatic Discharge Protection
Ø Maximum and Minimum Ambient Temperature
Ø Airflow Requirements
Ø Circuit Overloading
Ø Power Supply Connection
Ø Equipment Ground Connections
Ø Fiber Optic Cables
Ø Lightning Surge Suppressors
Ø Mechanical Loading
Ø Restricted Access
Operator Safety
This section sets out health and safety issues for personnel working with and around microwave radio equipment.
Radio Frequency and Microwave Safety
Radio frequency (RF) and microwave (µW) electromagnetic radiation spans the frequency range 3 kHz to 300 GHz (RF between 3 MHz and 300 MHz, µW between 300 MHz and 300 GHz).
RF/µW radiation is non-ionizing in that there is insufficient energy (less than 10 eV) to ionize biologically important atoms, so the primary health effects of RF/µW energy are considered to be thermal.
The absorption of RF/µW energy varies with frequency. Microwave frequencies produce a skin effect—you can literally sense your skin starting to feel warm. RF radiation, however, may penetrate the body and be absorbed in deep body organs without any warning signs.
RF/µW Safety Guidelines
Since the long-term effects of low-level microwave radiation upon the human body are not completely understood at this time, Harris Stratex Networks’ recommendations for maximum safety include the following:
v Do not operate microwave equipment without first having proper training or knowledge of microwave radio operation.
v Do not operate the microwave equipment without an appropriate antenna port termination, or antenna.
v Check to ensure that the area around the antenna is clear of personnel prior to turning the transmitter on.
v Do not look into or stand in front of an antenna.
v Do not swing or aim an antenna at nearby persons while the equipment is operating.
v Do not look into an open waveguide port while the equipment is operating as irreversible damage to the eye(s) may result. The waveguide directs microwave energy between the transmitter and the antenna and since the cross-sectional area of a waveguide is small, the power density is high and can be in excess of recommended safety levels.
§ Always exercise caution when working with open waveguides.
§ Turn off the power before working with waveguide connections.
v Where a structure or rooftop has existing antennas installed, do not proceed with an installation without first determining the RF/µW exposure risk. If necessary ask the structure/rooftop owner or operator. Where necessary have the relevant transmitters turned off or wear a protective suit for the duration of the installation.
RF Safety Standards
Refer to local safety standards for RF safety compliance requirements. Refer to the following safety standards for more information on RF emissions and microwave radiation safety :
v ANSI, 1982, “American National Standard-Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 300 kHz to 100 GHz.” Report ANSI C95.1 1982, American National Standard Institute,
v ANSI C95.5 - 1981, “American National Standard: Recommended Practice for the Measurement of Hazardous Electromagnetic Fields - RF and Microwave.”
v AS 2772.2 - 1988, “Australian Standard: Radio frequency radiation, Part 2 - Principles and method of measurement 300 kHz to 100 GHz.”
v European Commission - Non Ionizing radiation Sources, exposure and health effects doc CEC/V/F/1/LUX/35/95 -
v EUROPEAN PRESTANDARD, ENV 50166 - 1, “Human exposure to electromagnetic fields - Low-frequency (0 Hz to 10 kHz).” CENELEC, Ref. No. ENV 50166-1: 1995 (January 1995).
v EUROPEAN PRESTANDARD, ENV 50166 - 2, “Human exposure to electromagnetic fields - High frequency (10 kHz to 300 GHz).” CENELEC, Ref. No. ENV 50166-2: 1995 (January 1995).
v IEEE Std. C95.3-1991 - IEEE Recommended Practice for the measurement of Potentially Hazardous Electromagnetic Fields - RF and Microwave - IEEE, August 21, 1992 New York, USA.
v IEEE - ANSI (1992) - IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz - (Standard IEEE C95.1 - 1991. Revision of ANSI C95.1 - 1982)
v IEEE - Entity Position Statement (1992), “Human Exposure to Radio frequency Fields from Portable and Mobile Telephones and Other Communication Devices,” IEEE United States Activities Board, December 2, 1992.
Electrical Hazards
All HSX radio systems comply with global product standards for Safety, Extra Low Voltage (SELV) rated equipment. They are designed to operate from a nominal 48Vdc supply where the maximum voltage is not to exceed 60 Vdc. Accordingly, hazardous voltages are not used in the operation of HSX radio systems.
However, the power supply providing the nominal 48Vdc supply will normally be AC mains powered, and test equipment used in conjunction with HSX products may also be AC mains powered. Similarly, the rack into which the HSX products are installed may well contain other AC mains powered equipment. Voltages above 60Vac or dc can shock and kill.
Electrical Safety Guidelines
To avoid electrical shock, follow these recommendations:
Ø Check for possible hazards in the work area, such as moist floors, ungrounded power extension cords, and missing or doubtful safety grounds.
Ø Do not work alone if potentially hazardous conditions exist in your work space.
Ø Never assume that power is disconnected from a circuit. Always check the circuit before starting work.
Ø Locate the emergency power-off switch for the room in which you are working so that if an electrical accident occurs, you can quickly turn off the power.
Ø Ensure equipment is correctly protected with a fuse or circuit breaker.
Ø The power supply battery can have a short-circuit current capacity of many hundreds of amps. If short circuited before the fuse or circuit breaker, the resultant flashover can cause serious burn injuries. Ensure battery terminals and leads are suitably shielded against accidental short circuit.
Ø Install equipment in compliance with the following international or national electrical codes:
§ International Electromechanical Commission (IEC) 60364, Part 1 through Part 7.
§
§
§ Codes that apply to your country.
Ø Complete the entire installation and check the grounding, including connected peripheral equipment, before applying power to the radio system.
Ø Disconnect power to the radio system before replacing equipment, except as may be specified in the relevant equipment manual for powered-up swap-out, or installation of field-replaceable units.
Chemical Hazards
No hazardous materials are used in the construction of HSX radios and multiplexers. No special handling or disposal procedures are required, except that disposal must be as solid waste and not by burning or shredding.
Some HSX products include a Lithium Manganese battery. Replacement should only be performed by HSX service personnel, and spent batteries must be discarded as solid waste.
“For other manufacturer’s equipment, check their data sheets and instructions. Some local authorities may have special disposal requirements for batteries“
These requirements must be followed.
Chemical Hazards Guidelines
Chemical hazards may be present in your work area from other sources, such as battery acid, diesel fuel, cleaning agents, and asbestos building insulation.General safety guidelines when handling hazardous materials include the following:
ü Refer to the Material Safety Data Sheets (MSDS) for the chemicals you use.
ü Wear protective clothing, eye wear, gloves, face masks, or respirators as required.
ü Work in a well-ventilated area.
ü Avoid inhalation of smoke or fumes produced when material is heated.
ü Do not smoke near any potentially flammable products.
ü Do not wear oil-contaminated clothing.
ü After handling hazardous material, wash hands thoroughly with soap and water.
Laser and Fiber Optic Cable Hazards
Laser products are subject to international and US federal regulations and practices. IEC60825–1 and 21CFR1040.10 require manufacturers to certify each laser product as Class I, II, III, or IV, depending on the characteristics of the laser radiation emitted. In terms of health and safety, Class I products present the least eye hazard, while Class IV products present the greatest hazard. A label specifying the Class used should be placed on all devices equipped with a laser transmitter.
Class I laser products provide no danger to personnel from the laser transmitter when the system is in its operating configuration. All HSX radios and multiplexers equipped with laser transmitters use Class 1 devices.
Other transmission products or test equipment used in conjunction with HSX products may have laser transmitters of Class II or higher. While it is unlikely that Class IIIb and Class IV lasers will be encountered in telecommunications installations, should a label identify either, take extra care to avoid exposure as they can cause serious injury.
Laser and Fiber Optic Cable Safety Guidelines
When working with optical fibers, observe the following guidelines to minimize the potential for injury :
Ø Until checked and confirmed otherwise, regard all laser ports including unterminated fiber cables as ‘live’.
“Laser light within the infra-red or ultra-violet spectrum is invisible to the eye”
Ø Avoid direct exposure to fiber cable ends or open optical connectors in the laser signal path.
Ø Do not look into unterminated optical ports or fibers that connect to unknown sources. If visual inspection is required:
§ For optical ports, ensure the source equipment or its laser transmitter is turned off.
§ For fiber cable, disconnect the far end.
Ø Follow the manufacturer's instructions when using an optical test set. Incorrect calibration or control settings could result in hazardous levels of radiation if directed towards the eye.
Ø Protect/cover unconnected optical fiber connectors with dust caps.
Ø Handle optical fibers with care. Do not attempt to bend them beyond their minimum bend radius.
Place all optical fiber cuttings and bare fiber scraps in a suitable container for safe disposal. A bare fiber is a fiber that has had the primary coating removed, exposing the fiber's glass surface. These scraps are generated when splicing or terminating fiber during the cleaving process. Fibers and fiber scraps can easily penetrate the skin and eyes, causing a micro-injury that is difficult to handle.
Hoisting and Rigging Safety
Hoisting and rigging activities can result in accidents involving significant property damage, serious injuries, or death. Therefore, these activities must be executed with attention to safety.
Refer to the applicable country regulations for detailed requirements and
guidelines.
Harris Stratex Networks’ Requirements
The following guidelines are to be followed by HSX-approved engineering and installation subcontractors. The subcontractor’s quality procedures and safe working practices or any regulatory requirements in the country of installation must also be followed.
ü Operators and riggers must be properly trained and familiar with country regulations and requirements.
ü Hoisting and rigging equipment must be approved to the appropriate country standard. In some countries certificates need to be available for inspection upon request.
ü Hoisting and rigging activities must be carefully planned, and executed according to plan.
ü Hoisting and rigging equipment must be checked prior to the lift.
ü Hoisting and rigging equipment must not be used to lift personnel.
ü Ensure safety harnesses are correctly worn and used at all times when climbing.
ü Ensure hard hats are worn by all personnel working on and around the tower/structure.
ü Where appropriate, deploy warning signs such as “Danger Men Working Overhead” nd “Hard Hat Area” and close off the working area with cones or rope.
Climbing Certificates
Follow the climbing regulations of the country, which may require riggers and other tower-climbing personnel to have an approved climbing certificate.
HSX requires all riggers and tower-climbing personnel (including contractors and subcontractors) to have an approved climbing certificate. A copy of the certificate should be available for on-site inspection.
HSX further recommends that if a contracted rigger does not posses such a certificate then that person:
§ Cannot be classed as a rigger
§ Cannot be permitted to climb
§ Cannot be employed as the safety person for an approved rigger unless there is a second rigger in the vicinity with whom permanent radio or telephone contact can be maintained.
Permit To Climb
Follow the country’s regulations to obtain permission to climb. Such permission may not be granted if the site or structure owner or operator, or local authority, states that a structure is unsafe to climb.
Where the climbing activities are monitored by HSX, if the customer or a representative of the site owner, or other authority indicates that it is not safe to climb, no rigging will take place unless a senior rigger or structural engineer certifies that it is safe to climb.
General Site Safety
• Watch for protrusions or sharp or slippery surfaces that may catch or otherwise cause injury. Where possible, cover or restrict access to such areas.
• In a new installation ensure the placement of equipment does not restrict access to it and to other equipment.
• Ensure racks are securely anchored to the floor, and if necessary top-braced. Check to ensure that the additional loading of new equipment into a rack does not cause any reduction in mechanical stability of the rack.
Site Security
Ensure that the site is secure.
ü Check for any signs of physical damage or attempted entry on arrival at site.
ü On departure, check that doors, shutters, and gates are locked, access ladders removed or locked, and any site alarm activated.
ü Notify the operations center on arrival, and on departure.
General Hazards
This section describes protection and safety issues for microwave radio and associated equipment.
Electrostatic Discharge Protection
Electrostatic Discharge (ESD), also known as static electricity, is the sudden transfer of electricity between objects at different potentials. Static charges can cause damage to sensitive electronic components during installation and servicing. Your body can easily pick up a static charge, which can discharge to components or assemblies when touched.
ESD can cause immediate terminal equipment failure but can also cause latent damage, which while showing no immediate or obvious effect, may lead to premature failure.
“Personnel and equipment must be properly grounded when ESD sensitive assemblies are handle”.
ESD Handling Guidelines
To prevent ESD damage, follow these guidelines:
Ø Assume that all components, PCBs, and assemblies within a closed electronic housing are sensitive to ESD.
Ø Handle ESD-sensitive items only when you are properly grounded at a static-safe work area or when connected via a skin-contact ESD grounding strap to a ground on the equipment.
Ø Restrict handling of ESD-sensitive PCBs and sub-assemblies. Where practical handle assemblies via a front panel or the edges of a PCB.
Ø Store and transport ESD-sensitive items in static-shielding bags or containers.
Ø Ensure these handling procedures are maintained during the process of swap out/in of ESD-sensitive assemblies from/to their ESD protecting transport bags or containers.
Maximum and Minimum Ambient Temperature
Ensure compliance with the maximum ambient temperature (Tmra), and minimum temperature specifications for the installed equipment. Equipment performance cannot be guaranteed where ambient temperatures are outside specification.
Ø To maximize long term component reliability, ambient temperature limits must not be exceeded. Excessive heat is the number one cause of premature equipment aging and failure.
Ø At very low temperatures the equipment may not start, or may take considerable time to start up.
ODU Temperature Considerations
ODUs are normally specified for a maximum ambient temperature of 50° or 55° C. This is the maximum specified air temperature in shaded situations. Solar gain can raise the internal ODU temperatures by 10° Celsius or more, and in equatorial regions especially where ambients can be in excess of 40 C, over-heating may occur. In such environments the ODU should be protected with a sun shield.
Rack-mount Temperature Considerations
If equipment is installed in a closed or multi-unit rack assembly, the operating ambient temperature of the rack environment may be greater than room ambient. The maximum ambient temperature (Tmra) specified applies to the immediate operating environment of the equipment, which if installed in a rack, is the ambient applying within the rack.
Excessive heat is the number one cause of premature equipment aging and failure. Where possible avoid operating equipment at or near its maximum specified ambient.
Airflow Requirements
Rack installations must be made such that any airflow required for safe and correct operation of equipment is not compromised. Check the manufacturer’s installation manual for airflow requirements.
Circuit Overloading
Where an existing DC power supply is to be used for a new radio installation, check the supply has sufficient spare capacity to do the job. Also check that any circuit protection devices and intermediate dc supply wiring will not be overloaded.
Power Supply Connection
Most HSX radios require a -48 Vdc, +ve grounded supply, where the +ve pin within the radio dc connector is fastened directly to the chassis. Such radios must be supplied from a -48 Vdc power supply which has a +ve earth (the power supply earth conductor is the +ve supply to the radio).
- There must be no switching or disconnecting devices in the earth conductor between the dc power supply and the connection to the radio.
- The radio should be located in the same immediate area (same or adjacent racks/cabinets), as any other equipment that is connected to the same earthed conductor of the same dc supply circuit.
- The power supply should be located in the same premises as the radio system.
Equipment Ground Connections
Reliable grounding of radio equipment must be maintained. Refer to product installation manuals for product-specific grounding instructions. Such instructions should provide details for grounding an ODU, ODU/IDU cable, lightning surge suppressor, and indoor units. For general lightning protection and site grounding requirements, refer to Chapter 6.
Fiber Optic Cables
• Handle optical fibers with care. Keep them in a safe location prior to installation.
• Do not attempt to bend them beyond their minimum bend radius.
• Ensure they are correctly secured and protected from accidental strain once installed.
• Protect/cover unconnected optical fiber connectors with dust caps.
Lightning Surge Suppressors
All HSX radios must be fitted with the specified lightning surge suppressor(s) to avoid voiding the warranty.
Refer to the product manuals for details of suppressor types required and their installation.
For general lightning surge suppressor installation and cause and effect data, refer to Chapter 6.
Mechanical Loading
§ When installing the indoor unit in a rack, ensure the rack is securely anchored to the floor and top-braced if necessary.
§ Ensure that the additional loading of new installations will not cause any reduction in mechanical stability of the rack.
Restricted Access
§ Radio equipment must be installed in restricted access areas.
§ The indoor unit and associated power supply should be installed in lockable equipment rooms, closets, cabinets or the like.
§ Access to the tower and ODU/antenna location must be restricted.
Extra attention to rack anchoring and fastening will be needed in earthquake prone countries.
Follow local authority requirements and recommendations.
