I N N O V A T I O N A N D F L E X I B I L I T Y
T H E
I N S T A L L A T I O N A N D M A I N T E N A N C E T R A I N I N G M A N U A L
3.8.2 Direct Installation ~ Pulling into a duct
The ratios to allow for air flow (as stated above) do not apply, e.g. with a winch and rope. Remember, that to pull a cable into a duct, it is necessary
to allow for extra cable ‘diameter’ caused by the pullsock arrangement at the front. The cable is likely to have an end cap on the leading end and the
pullsock itself over that.
Tube Assembly
PVC Tape
Pull sock
End Cap
Swivel and fuse
Pull rope
Duct
Available Space (multiple cables)
There are various ways to calculate the approximate ‘available space’ in a partly occupied duct. Let us define
‘realistic space’ ‘R’ as 0.92 of the empty duct diameter.
This 8% allowance assumes some reduction of the
ID due to bends and distortion.
Empty duct:
The ‘available space’ = R.
E.g. a 50/40.6 empty duct could be said to have 37mm available space (40.6 x 0.92)
One Cable already installed
The ‘available space’ = R – D1 (where D1 is OD of existing cable)
Two or more cables already installed
of diameters D1, D2, D3, etc in decreasing order of size.
(a) Where D1 > 2(D2 + D3 + ...)
The ‘available space’ = R – D1 (where D1 is OD of largest cable)
(b) Where D1 < 2(D2 + D3 + ...)
The ‘available space’ = R – 0.8D1 – 0.6D2 – 0.4(D3 + D4 + ...)
3 Outdoor Installation
“This document is intended as a guide only. Whilst the information it contains is believed to be correct, Emtelle can take no responsibility for actions taken based on the information contained in this document. Emtelle reserves the
right to make changes to this document without notice. All sales of product are subject to Emtelle’s terms and conditions of sale only, which can be found on Emtelle’s website.”
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