Conduit / Heat Dissipation

[clicon357]

Probably thinking too much again but.........does the reference method vary as to whether fitting T&E in OVAL or ROUND conduit and again whether that conduit is steel of PVC. Just thinking that steel might have better heat dissipation properties than PVC etc.

 

[malcolmsanford]

I have yet to see a formula that takes into account any factors for T and E in conduit. Most formulas including appendix 5 in the OSG deals with singles either stranded or solid conductors and factors in length of run, bends etc etc.

Table 4D5 in the BRB does show T + E in a conduit to be erection method A and is derated accordingly, but does not distinguished between oval or round, but does say that is if in an insulated wall, so I would treat oval and round as exactly the same.

To be honest if you are getting to the point of worrying what containment form is better for dissipation I think we may need to redesign the circuit.

 

[clicon357]

No particular circuit. Helping my son with his homework about energy efficiency around the home and was discussing the various wall constructions over the years. I was just musing on the conduit shapes/volumes/materials and then over the shall we say potential "benefits" of the common method of burying T&E directly in an UNINSULATED solid wall (mine are 13" brick - no cavity). No good in terms of insulation but "cold" all year round. Wondering on the effect of the thermal mass of the wall in lowering the ambient temperature that the cable is working in. Albeit for only short runs of the cable length as when it then starts running through loft spaces etc it all changes again. Must stop thinking!

 

[La Poste]

I thought this correction factor for heat dissipation and grouping was only used when the cables were going to operate at there full working temperatures.

I mean what sort of temperatures are we talking about if a 2.5mm single or even a 2.5mm T and E is running 10 Amps at room temperature?



I don't have the regs handy to check this.