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Types of cables acceptable in flexible conduit

Baldyhugh

Hi

I am planning an upcoming job at the moment and a query has come into my head regarding flexible conduit. Are there only certain types of cable that are acceptable to use in flexible conduit? I am installing some high level light fittings and have a horizontal run of PVC conduit which I plan to drop out of at each light position from a tee box with a short length of plastic flexible conduit to each light fitting. I am using 7 core stranded conduit cable (6491X) and looping in/out at each fitting. Is 6491x stranded conduit cable acceptable in flexible conduit or should the cable also be flexible. Also is single insulated cable acceptable or should it be insulated and sheathed? The flexible conduit will be fixed in position so wont be able to move, the only reason im using it is to save having to make rather awkward bends with pvc conduit. 

I must admit to using this type of cable many times before with flexible conduit without any thought but am now wondering if its acceptable.

Id welcome your thoughts.

Thanks

Peter 

  • 0

    I don’t see any issue. 521.1 refers to Table 4A1 which permits your proposal. So if the flexible conduit and wiring within are suitable for the external influences to which it will be subject and that it all complies with 511, crack on.

  • 0

    If you had said that you were using the flexible conduit in a way that will be regularly flexed - as part of a moving machine or to get wiring onto some fitting on door perhaps - then  fine stranding would make sense. But here it is flexible to install,  then once in position essentially a non-mover,  then the coarser stranded stuff will be fine. The plastic conduit serves the same mechanical 'double fault to danger' as a sheath on a normal flex so single insulation is fine unless the wiring is exposed at one end or the other for some reason.

    Mike.

  • 0

    I cannot see any problem at all. The only long term issue is that the conduit itself may become brittle, but if it is inaccessible, that will hardly matter.

  • 0 in reply to mapj1

    Thanks for your replies. The flexible conduit that I will be using is the heavier ribbed black plastic type with the screw on glands so hopefully it will be a bit more durable than the lighter type. I assumed but wasn’t certain that the flexible conduit acted as an ‘outer sheath’ of a cable and as such permitted single insulated cables to run through it. Thanks again for your advice

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