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Perforated Cable Trays

Stuart Urban

Is anyone aware of a cable tray manufacturer that makes perforated cable trays with more 30% or more of holes? I've checked a few online and they all seem to be classification C. Can this only be achieved by using basket? 

Extract from BS7671:

APPENDIX 4 (Informative)

CURRENT-CARRYING CAPACITY AND VOLTAGE DROP FOR CABLES

7.2 Other Methods

"Cable tray systems: A perforated cable tray has a regular pattern of holes that occupy at least 30 % of the area of the base of the tray. The current-carrying capacity for cables attached to perforated cable trays should be taken as Reference Method E or F. The current-carrying capacity for cables attached to unperforated cable trays (no holes or holes that occupy less than 30 % of the area of the base of the tray) is to be taken as Reference Method C."

Extract from manufacturers data sheet:

Parents
  • +1

    To get to more than 30% holes is quite see-through, and not in the realms of the sort of thing that can easily be punched from flat sheet without it all falling apart, where the holes remove  typically less than 25% of the weight and as such are mostly blocked from airflow by the cables they are supporting.

    You may look at cable ladder tray style tray

    if you want something more beefy and less easily distorted  than baskets or as it is also called mesh tray

    Mike.

Reply
  • +1

    To get to more than 30% holes is quite see-through, and not in the realms of the sort of thing that can easily be punched from flat sheet without it all falling apart, where the holes remove  typically less than 25% of the weight and as such are mostly blocked from airflow by the cables they are supporting.

    You may look at cable ladder tray style tray

    if you want something more beefy and less easily distorted  than baskets or as it is also called mesh tray

    Mike.

Children
  • 0 in reply to mapj1

    That's what I'm thinking but how many of us have assumed that the "standard"  perforated cable tray is not what BS7671 define as a perforated cable tray.

  • 0 in reply to Stuart Urban

    true - it probably ought to say 'basket or ladder' really, to avoid confusion. I'm not sure how common it is for installations to be that close to the edge though - once you start filling  basket the airflow is not that much better.

    M.

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