Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This Question of the Day, concerning the sizing of cable basket and tray, is answered by Legrand:
|
| Legrand's Topaz cable ladder. |
|
|
| Cable tray - how to size it? |
|
|
Question: I am doing a project where all of the PVC/PVC T&E cables and SWA sub-main cables are run on cable trays above a suspended ceiling. Can you please tell me how to define the size of cable tray I need?
Answer: For cable trunking, i.e. containment, it needs to comply with the Wiring Regulations (BS7671), which states that the installer should not exceed the 45% space factor. When using cable support systems, such as tray, there are no rules regarding space factors, and it is not covered by the Wiring Regulations. All you need to do is multiply the height by width of the cable tray to obtain the cross sectional area (CSA).
Then, for each cable size, multiply the number of cables by the outside diameter and then add the totals together to give a grand total. Obviously, this must not exceed the CSA of the tray.
Just one note - the Wiring Regulations require segregation where cable systems have different operating voltages and different levels of cable insulation. This can be achieved by fitting a divider into the tray.
To see many more Q & A in Voltimum UK's Experts Area, please click on the link: http://www.voltimum.co.uk/consult.php?universe=consult.index.questions
|
Related contacts
|
Legrand Electric Ltd.,
Great King Street North,
Birmingham B19 2LF
Tel: 0870 608 9000
Fax: 0870 608 9004
Email: legrand.sales@legrand.co.uk
Web: www.legrand.co.uk |
Legrand
|
| Source: Legrand & James Hunt |
|
|
Back