Any reference to UK regulations would be appreciated.
Shield, shield, shield with a perfect ground.
Large 3phase cables data backbones and fire security cabling may share the same man holes or draw pits, provided the cables should be properly tagged and separated with sufficient space.The man hole should be at least 660mm X 550 mm and a depth of 1800 mm. The man hole cover should be at least 660mm diameter. Distance between power cables and the fire/security cables may be referred to the local codes.
The short answer is yes. The longer answer is that there are severe electromagnetic field and physical access requirements which must be met to do this successfully. The field isolation is accomplished in three ways: group cabling according to type and use in separate ducts, keep transmission and return paths together, make ducts of materials sufficient to attenuate stray fields from the cabling within, and from outside to the cabling within. Particular care must be taken to ensure that no duct shielding is ever part of a current carrying path, and that currents induced by stray magnetic fields are adequately attenuated and diverted to local grounds to minimize field penetration within the ducts. To effect this, supply and return paths are kept close together within each duct. i.e., coaxial cables with their shields providing the returns in data ducts, phase and ground return cables for each power duct, and similar systems, must be correctly designed and installed. All connectors throughout the system, as well as the draw pit routing, must be designed to provide return paths for all signals to be completed through the shields and ground paths contained in the individual cable groups. There must be no external closed paths that would permit large stray magnetic fields around the individual groups. The individual ducts should also be designed as part of a total structure, permitting safe physical access for maintenance, etc, and also measuring interference fields and current imbalances between transmission and return of power and/or data. A great deal of insight can be obtained from the internet, not only for regulations, but by browsing actual proposals for constructing integrated power and communication systems. At the heart of all successful distributed systems is proper design of cabling and connectors to keep transmitted and return current paths as closely grouped as possible, together with proper shielding.
