Rating factors
Revit Guides
Data Management
Rating factors are divided into the nominal rating of the circuit protective device (In) to determine theminimum current-carrying capacity (Iz) of a cable in a circuit. For example:
Iz = In/(Ca x Cg x Cc x Ci x Ch)
Rating factors:
Ca –ambient temperature
Cc –buried installation methods 70 to 73 (Cc = 0.9)
Cd –for depth of burial
Cf –BS3036 protective device (Cf = 0.725)
Cg –grouping
Ci –cable run through insulation
Cs –for thermal resistivity of soil
Ch –3rd harmonic current
Separation Gap for Primary and Secondary Life Safety Cable Trays Roof Installation)
UK electrical and fire safety standards do not prescribe a fixed minimum separation distance for roof-mounted life-safety cable trays. However, BS 7671, BS 8519, and BS 5839 collectively establish that life-safety circuits must be installed on dedicated containment and be either separated by barriers or adequately distanced to ensure circuit independence.
Level of information need
Ever feel like you’re drowning in BIM data you don’t need, or scrambling for details that should’ve been there? Enter the concept of Level of Information Need. It’s a straightforward idea buried behind a not-so-straightforward name (looking at you, BS EN ISO 7817-1:2024). In plain English, a Level of Information Need defines exactly what information should be delivered – no more, no less – for a given BIM use case or project stage.
