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BHARAT Sf,HCHAR HIGAH LIIhIITED
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Office of the Chief General Manager
NWO-GFA Gell
Kerala Circle, PMG Jn., Trivandrum-695033
Phone: 047 1 -2303434,Mobi1e No.9446039977
Email: gvsangvsan@gmail.com
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ALL SSA HEADS,
Kerala Circle.
No.AT/14-1IGENL/2014-15/
datedatTVM the 03/03'2015
Sub: Protection & Safety Measures for Telecom Building
/ Equipments - reg.
As per the discussions in the Exchange Expert Committee Meeting and inputs from
Electrical Wing, the following guide lines are reiterated.
Protection of Telecom Buildings and equipments
Building Protection:
1.
Ensure that proper lightning protection system is provided in all our buildings, lf it is not
provided already, the same may be done on priority.
The following points may be checked in the case of existing lightning protection system
Lightning conductor finial (Air terminations), Gl / Copper horizontal and vertical
conductors (vertical and horizontal air terminations), test joints and earth
(i)
(ii)
(iii)
(iv)
terminations are provided as per the specifications.
Continuity of the vertical and horizontal conductors up to earth pit shall be
checked and ensured. Broken conductors on the terrace / walls of building, which
is not connected properly to earth terminal will attract lightning in the vicinity and
cause more damages than a building without protection.
Check for proper earth values at test points'
ln places where the building comes within the zone of protection of tower
(450 angle with a base radius equal to the height of the tower), separate lightning
conductor for building is not required.
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Replacement of SPD:
At LT supply incoming point, provision of Class B lightning protection (surge
protection device ) with spark gap devices along with Class C device before pow?f
plant ( if not provided inside power plant
be replaced.
) shall be provided. lf it became faulty, it should
Replacement of SPD Catridges:
Timely replacement of cartridges by seeing the visual indication, also shall be
ensured to keep the surge protection system functional.
Earthing:
1.
2.
3.
A Gl strip of 50 x 3mm is to be laid in a trench 30 cm wide and depth 1 to 1.5m. around
the building for ring earthing. The trench to be minimum 1m away from the building.
Ring earth will act as equipotential bonding and all earthing of equipments to be
extended from ring earth.
There shall be a separate Ring Earth around the Tower in case of Ground Based Tower
( GBr)
4.
S.
6.
7.
8.
g.
Tower lightning protection system shall have Two down conduclors connected to
separate earth pits and subsequently connected to the ring earth.
The sheath of the cable for Aviation warning lamp on tower, if armoured, should be
separately connected to the tower at the top end, and to the ring earth at the bottom end
by Gl strips.
To extend the power supply to Aviation Lamp on tower, isolation transformer shall be
provided.
All wave guide terminations shall be individually connected through copper conductors to
the common ring earth.
For Roof Top Tower (RTT ), 50x3mm Gl strip down leads should be bonded to any two
opposite tower legs and brought down along outside of the building and connected to
ring earth.
Due to non-availability of space around the building, where only plate earth is provided,
then Gl strip (50x3mm.) down leads should be brought down along outside of the
building and connected to plate earth
10. There shall be a separate Plate earth for the Tower'
11. The different Plate earths in the pit shall be interconnected for equipotential bonding.
12. Commoning of all existing earths i.e., tower earth, building earth, lightning earth,
equipment earth, power plant earth, EA body earth etc., shall be done to bring
equipotential situation.
13. Neutral of transformer / Engine alternator shall be earthed separately.
14. The Main Earthing Terminal shall be installed on the externalwall of the building o!"near
the external cabte entrance on outer wall.
?*4"
\
15' The sheath of the external power and telecom
cables shalt be bonded to the Main
' Earthing Terminal. The purpose behind this arrangement is that all the lightning
inductions outside the building will be grounded before entering
the building itself.
16. The following are connected to the Main Earthing Terminal:
Lightning protection System
A/C Power distribution Protection Earthing i.e. the Cable shield of the
A/C power
cable
External cables
Tower Earth
The Common Bonding Network
17. All the earthing arrangements and condifion of lightning arrestors and SpD shall
be
checked periodically.
(i)
(ii)
(iii)
(iv)
(v)
18.The earth resistance should be less than or equal to 0.5 ohm for individual
earth
connected to equipotential bonding. only in exceptional cases, earth resistance
is
allowed up to 1 ohm.
.
Fire protection:
1.
2.
?
4.
5.
Check the provision of suitable smoke and heat detectors in Exchanges with
fire alarm panel, manualcall points and heaters.
Check whether AFD System is provided in all equipment rooms including
server room,
Power room & E/A room.
Check whether all independent AFD systems in the building are integrated.
Recent date of fire drill conducted for equipping the staff tackling fire incidents.
Check whether adequate no. of fire extinguishers provided in each floors.
Half yearly
checking and refiiling of fire extinguishers are to be done.
It may be noted that we have just two months before lightning and rain
commences from
May 2015. Hence it may be ensured that allconcerned officers pedorm
a thorough check of the
above protection and take necessary correction active for repair / replacement
oitne same. The
Controlling Officer may monitor the implementation of these guidelines
and ensure 1O0o/o
cbmpliance. Electrical wing may be consulted for guidance.
O/o CGMT, Kerala Circle,
Trivandrum.
Copy to:-CE(E), TVM
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