AS NZS IEC 60825.2:2011 pdf – Safety of laser products Part 2: Safety of optical fibre communication systems (OFCS).
b) Locations with restricted access (see 3.14):
— secured areas within industrial premises not open to the public;
– secured areas within business/commercial premises not open to the public (for example telephone PABX rooms, computer system rooms. etc.);
— general areas within switching centres;
— delimited areas not open to the public on trains, Ships or other vehicles.
c) Locations with unrestricted access (see 3.15):
– domestic premises;
— services industries that are open to the general public (e.g. shops and hotels);
— public areas on trains, Ships or other vehicles;
– open public areas such as parks, streets. etc.;
– non-secured areas within business/industrial/commercial premises where members of
the public are permitted to have access, such as some office environments.
OFCS may pass through unrestricted public areas (for example in the home), restricted areas within industrial premises, as well as controlled areas such as cable ducts or street cabinets. Optical local area networks (LAN5) may be deployed entirely within restricted business premises.
Fibre systems may be entirely in unrestricted domestic premises such as hi-ti interconnections.
For requirements on infra-red (IR) wireless LAN5 or free space optical systems, see separate applicable part of IEC 60825-12 (16].
D.2.2 Typical system components
a) Fibre cabies. single fibre/multiple fibre/nbbon construction
single mod&multimode
all dielectric or hybrid construction
carrying single/multiple wavelengths
uni!bidirectional fibre
communications/power feeding
b) Optical sources: LEDs. VCSEL, Fabry Perot or DFB lasers, pump lasers, optical amplifiers
bulk/distributed. continuousilowlhigh-frequency emission
C) Connectors: simplex!duplexlmultiwaylhybrid
d) Power splitters, wavelength multiplexers, attenuator
e) Protective enclosures and housings
f) Fibre distribution frames
D.2.3 Typical operating functions
a) Installation
b) Operation
C) Maintenance
d) Servicing
e) Fault-finding
f) Measurement (including optical time domain reflectometry (OTDR))
This ratio is less than 1; thus, the accessible emission is within Class 1 limits and so hazard level 1 applies at that location.
0.4.2 BI-directional (full duplex) transmission
There is no additive effect from each separate direction of transmission, as each broken fibre cable end represents a separate hazard If the fibre breaks. The hazard level is determined by the transmission direction with the higher power.
0.4.3 AutomatIc power reduction
By using automatic power reduction in an end-to-end OFCS it is possible to assign a lower hazard level than would otherwise have been the case. This Is important when the hazard level of the internal optical transmittersiamplifiers of a system may put a limitation on where that system may be deployed. See Annex B.
Automatic power reduction should not take the place of good working practices and proper servicing and maintenance. Also, the reliability of the APR mechanism should be taken into account when assessing the hazard level
Assessment of Ihe hazard level should take place at the lime of reasonably foreseeable human access to radiation (for example after a fibre break), unless measurement at a later time would result in a larger exposure (see 4.8.1 and 4.8.2).
Automatic power reduction cannot be regarded as a universally protective measure because, after a fibre break, it is common practice to use an optical test set (usually an optical time domain reflectometer, OTDR) to determine the location of the break. This instrument launches laser power down the fibre under test. Therefore, even if the normal telecommunications transmitter is shut down or removed, the diagnostic instrument could, at a later time, apply laser power to the fibre.
These OTDRs typically operate at Class 1, so no potential hazard is present at such sources
However, higher power systems have a longer range and may require Class IM, Class 3R or
Class 3B OTDRs to detect the break. Also, OTDR signals may be amplified to a higher Class
If sent through an optically amplified system.