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Cable Overblowing Junction Box

The CBS Cable Overblowing Junction Box has been designed to install a new cable or duct-tubes into an existing occupied sub-duct (subject to space being available).

The Cable Overblowing Junction Box comprises a robust aluminium base and lid that form a pressurised air chamber into which one end of an existing occupied sub-duct can be attached. The existing cable can exit the Cable Overblowing Junction Box through an opening that has 3 cable seal slots, one of which will house the seal to suit the size of the existing cable. The third branch is then connected to a CBS Cable Blowing Machine via. a short slave length of sub-duct for the installation of the extra cable or tube(s).

A range of Overblowing junction boxes are available to suit the outside diameter of the sub-duct.

The maximum diameter of a new cable / tube(s) for installation is dependent on the diameter of the existing cable and duct bore.
It is the responsibility of the operator to ensure that the cable / tube(s) to be installed are compatible with the existing sub-duct and installed cable configuration.



Cable range limit 9-20 mm O.D.

Duct range (Note: one duct O.D. size per unit)
Minimum 25 mm O.D
Maximum 50 mm O.D

Viscous Drag

Max. operating pressure 12 Bar


For Ducts with an Inner Diameter of: Minimum Flow Acceptable 

0 up to 25mm   : 4m³/min 150 CFM
26 up to 30mm : 5m³/min 185 CFM
31 up to 35mm : 7m³/min 250 CFM
36 up to 40mm : 10m³/min 375 CFM
41 up to 44mm : 12m³/min 450 CFM


LENGTH: 295 mm
HEIGHT: 74 mm
WIDTH: 170 mm
WEIGHT: 4 kg

Cable Overblowing Junction Box

Ordering Info

Product NoDescription
C-1253-32 32mm Duct O.D.
C-1253-40 40mm Duct O.D.
C-1253-50 50mm Duct O.D.

 Other sizes available on request