cable route under stairs

[zap]

I'm aware of drilling and notching limitations in joists but do they apply to the area under the flat platform (4 steps from the top) on a 90 degree bend in a staircase?
Any guidance would be welcomed.

 

[telectrix]

if less than 50mm deep and not in prescribed zones, then 30mA RCD and steel plate or earthed conduit is required.

 

[Richard Burns]

I would say that the requirements are not specifically designed for this situation, but consideration should be given to the fact that this is still a supporting structure for a floor area, however small.
I think that the best approach would be to use as small a penetration as you can and consider the anticipated strength reduction you would impose on the joist.
IF there is space to go below the joists rather than through them this would be preferred. (does depend on what is in the cupboard under the stairs, if any.)

 

[zap]

Thanks for all your input.
The area under the stairs will be a wc and yes, there is a window.
The ceiling in this area (not including the slope of the stairs, is roughly 1m x 1.5m with the joists across the 1m. Currently the joists are visible so drilling would be quick and easy. The ceiling will be plasterboarded and the fire rated led lights sunk into it.
The joists are too small to be drilled i.e. < 100mm deep. Therefore, according to the regs. notching appears to be my only alternative. This means dismantling the staircase to create the notches and protect with metal plates.
I don't think my client will like this solution, in fact I can already hear the, "WTF".
Maybe this is one of those occasions that a judgment call is made, which I think Richard intimated.

 

[polo1]

Can you not notch the joists without dismantling the staircase - say using a Fein? Got to be easier that stripping down part of a staircase (and you're unlikely to rebuild it as tight as it was).Regards

 

[ayjay]

just drill the blo--y things

 

[zap]

Thanks polo1.
I've youtubed a Fein and I must admit I've never heard of them. I was impressed!
Good call, I'll speak to a chippy mate and maybe get a demo/borrow.

 

[Guitarist]

Or drill through near the surface and plate over the point where the cables pass through at <50mm