home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Internet Standards
/
CD2.mdf
/
ccitt
/
1992
/
l
/
l3a.asc
< prev
next >
Wrap
Text File
|
1991-12-30
|
2KB
|
63 lines
Recommendation L.3
Replace point 8 and onwards by the following:
8. Through-connection of armouring
In case long-distance cables or similar cables are provided with metal
armouring, this should be through-connected electrically at the splicing
points. This should be done to obtain maximum protection against the effects of
atmospheric discharges and protection against induction.
Metal armouring on cables forming part of the distribution network
should also be through-connected in case such protection is needed.
In case metal-armoured cables are also provided with a metal sheath it
may be desirable to through-connect this and the armouring electrically at the
splicing and/or repeater points. This should be done to neutralize any differences
in potential between the armouring and metal sheath, and to obtain maximum
protection against magnetic interference. Through-connection may create corrosion
problems, which will usually reduce the lifetime of the metal armouring.
9. Omission of armouring
On directly buried cables, metal armouring can be dispensed with in case
the cable is provided with a strong plastic sheath, for example of polyethylene.
A further prerequisite is that the soil and laying conditions should be
favourable.
Additional protection, for example of optical fibre cables, may be
obtained by providing the cable sheath with an external layer of polyamide (thickness
0.4 - 0.5 mm). This has a favourable effect as a wearing surface when drawing
the cable over long distances. Moreover, the layer gives a certain degree of
protection against light mechanical attacks.
9. 10. Corrosion considerations - cables with metal sheaths
(No change to the text.)
10. 11. Rodents and insects
Damage from rodents and insects to direct buried cables may be high in
some areas. In those locations, it may be advisable to consider the application
of some type of armouring. For detailed information regarding armour protection
against rodent and/or insect attack, the reader is directed to Part IV-B, Chapter
II of the CCITT Handbook "Outside plant technologies for public networks",
mentioned in Recommendation L.1.
11. 12. Tropical countries
(No change to the text.)