Dear Experts,
My cooker circuit is 10mm^2 singles in 20mm steel conduit. Currently it has a 32A RCBO and supplies only a 16A oven, though it did have a 40A MCB at some point in the past.
It runs under my living room floor, which is currently a 75mm void between concrete/screed and wooden floorboards. I am about to insulate this. This conduit will need to run in some sort of channel through the insulation.
My options include:
- 25mm PIR board on top of the screed, conduit laying on top of that, 30mm gap, flooring. (This is what I am doing for the water pipes. The conduit could be in the same space as the cold water pipe, but it will be well-separated from any hot pipes.)
- Conduit in contact with screed, 30mm gap, 25mm PIR board, flooring.
- Conduit in contact with screed, no insulation above or below.
I don’t have a handy table of the current-carrying capacities for singles in steel conduit. I have a vague feeling that it’s the same as PVC T&E of the same diameter - is that right? Nor do I have any numbers about how this should be derated for the installation near insulation. Can anyone help?
It’s unclear to me whether it’s better to have insulation below (since heat rises) or insulation above (since that would allow heat to conduct into the cold concrete).
(As an aside, I just went to check if the cables were definitely 10mm^2 and found that the live was completely loose in the terminal in the cooker switch. There was a tiny bit of melting of the insulation but otherwise it’s in amazingly good condition!)
My cooker circuit is 10mm^2 singles in 20mm steel conduit. Currently it has a 32A RCBO and supplies only a 16A oven, though it did have a 40A MCB at some point in the past.
It runs under my living room floor, which is currently a 75mm void between concrete/screed and wooden floorboards. I am about to insulate this. This conduit will need to run in some sort of channel through the insulation.
My options include:
- 25mm PIR board on top of the screed, conduit laying on top of that, 30mm gap, flooring. (This is what I am doing for the water pipes. The conduit could be in the same space as the cold water pipe, but it will be well-separated from any hot pipes.)
- Conduit in contact with screed, 30mm gap, 25mm PIR board, flooring.
- Conduit in contact with screed, no insulation above or below.
I don’t have a handy table of the current-carrying capacities for singles in steel conduit. I have a vague feeling that it’s the same as PVC T&E of the same diameter - is that right? Nor do I have any numbers about how this should be derated for the installation near insulation. Can anyone help?
It’s unclear to me whether it’s better to have insulation below (since heat rises) or insulation above (since that would allow heat to conduct into the cold concrete).
(As an aside, I just went to check if the cables were definitely 10mm^2 and found that the live was completely loose in the terminal in the cooker switch. There was a tiny bit of melting of the insulation but otherwise it’s in amazingly good condition!)
