The CWU has agreed with BT that live fibre laser work within the BTUK network could commence from 25 April 2000 after lengthy and detailed assessments and discussions between BT and the union stretching back over the past five years.
This followed changes in the International and British Standards in 1993. Under these standards, Class 3A power level limits are currently 21.6 milliWatts at a wavelength of 1300 nanometres and 50mW at 1550 nanometres. BT say that most of their systems are well inside these limits, with power levels of between 10 microWatts (0.01milliWatts) and 5 milliWatts.
The existing ISIS document SFY/CSP/B039 has been extensively revised to include what BT say is a definitive list of all the types of equipment in use in their UK mainland network. A new ISIS SFY/CSP/B035 has been devised to cover labeling of equipment. BT claim that all their UK mainland systems in use are Class 3A or less, and therefore are safe for live working even during fault or breakdown conditions, when people will be required to work on them. See also CWU briefing Vol.5 No.14 Paragraph 243(14/4/00).
If you have any concerns that any local UK system either is not included in the list attached to the ISIS documents or have evidence that they emit power level above that of the limits described, then let your branch know immediately.
The CWU have been assured by BT that any system found not to comply with these limits, will be replaced by new equipment that does.
Excluded from these arrangements are some Intercontinental sub-sea systems up to their first landfall station and those for research purposes, such as at Adastral Park (Martlesham), which may still be Class 3B or even 4. All of these systems will still be subject to the more stringent safety standards and will operate as closed user groups.