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The new BS EN 1917 2002 for
Manhole Rings which will
supersede BS 5911 in October
2004, requires a minimum 600mm
circular access opening in manhole
cover slabs.
The preferred access opening by
specifiers are 675x675 square and
675 circular.
The most recent amended
BS 5911 gives alternatives,
minimum access opening 600x600
for manhole DN 900 and DN 1050.
Min access opening 675x675 square opening for
DN 1200 to DN 3000.
However provision is also made for
larger access openings in BS 5911
with a distinction made in relation
to depth of manhole.
Where manhole less than 1.500
deep (generally 1200x675)
Where manhole more than 1.500
deep (generally 750x600)
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