Volume-IF - JantERmantER

TITLE SPECIFICATION NO. PES-509-02A
LIGHTNING PROTECTION &EARTHING
OF CHIMNEY
(SUPPLY & INSTALLATION)
VOLUME
II B
SECTION
D
REV NO. 0 DATE 08.02.2002
SHEET 3 OF 4
annular horizontal air term inations. The vertical air term inations shall be electrically
connected (Brazed) to the horizontal air term inations, the vertical term ination of the
flues and those of the Chim ney to the hor izontal term ination of the Chim ney. The
vertical terminations shall be spaced not more than 3m apart from each other.
3.2 The air term inations shall be secured to the top of Chim ney top by an arrangem ent of
substantially strong construction to withstand high wind pressure prevalent in the area
commensurate with the height involved. A ll m aterials for the securing arrangem ent
shall be of the sam e grade as the conductors and must be galvanised. The vertical air
terminals at the top of the shell shall also be secured to the guard ring at the top of the
shell.
3.3 A minimum of two num bers of equally spaced conductors, each consisting of 50x6m m
GI strip, shall be brought down from their connecting points on the annular rings at the
top of the Chim ney/flues. The down-conductors originating at the top of the flues shall
be brought down along the walls of the flues a nd electrically connected (welded) to the
annular ring at the top of the outer sh ell of the Chim ney. The down conductors
(minimum two num bers) from the chim ney top shall be brought down to the bottom of
the Chimney all along the exterior Chimney wall.
3.4 A test link of copper black/phosphor bronze gunm etal bolted to the conductor for the
purpose of isolation & testing shall be provided on each down conductor 1000mm above
ground level.
3.5 Down conductors shall be cleated to the wall at an interval of 1500m m all along the
length of the Chimney.
3.6 Down conductors near ground level shall be protected against m echanical injuries by
means of wood-m oulding or non-m etallic cove r. A rem ovable cover of the sam e
material shall be provided over the test- link for easy access.
3.7 The connection between the downconductor from the test link onwards upto an annular
ring of galvanised steel running around the en tire periphery of the chimney bottom shall
be provided through risers which shall be of 40mm dia MS rods.
3.8 The risers shall be term inated on the annular ring of 40m m dia MS rod running around
the periphery of the chim ney buried 1 m etre deep in the ground and clearing all
foundation by at least 2 metres.
3.9 From the term ination points of the downconductors on to this underground ring, m ild
steel rods shall terminate at test pits complete with test-links and electrodes.
3.10 The test pits at para 3.9 shall in turn be connected to the m ain earthmat of the power
house through 40mm dia MS rod.
3.11 All joints, except for testing purposes, shall be welded type lap joints with an overlap of
100mm. The welding shall be com plete around the joint and not tack welded. Electric
arc welding shall be used for all joints.
3.12 After welding, two coats of anti-corrosive (red-oxide) paint followed by a coat of
bituminous paint shall be applied to each joint.
3.13 The 40m m dia MS rods shall be protected against corrosion by applying a coat of
barium chromate paint and two coats of bitumen below the test link.