Hi,
The ongoing plans of the bungalow... Will be doing a rewire under LABC notice in a few months. Part of bungalow renovations include stripping the dormer conversion back to the skeleton, so an excellent time to get plumbing and cable management right. All existing services are to be stripped out first.
I have a triangular-cross-section void running horizontally right around the perimeter of the house, minimum size about 35-45cm horizontal width and
35-45cm height. In several places this opens out into relatively large areas.It would be nice to run all the electrical circuits principally around the perimeter void, coming along the sides of joists for drops. This avoids butchering the already butchered joists any more (of course the myriad notches and holes won't be where I want them...)
For the joist runs, clipped direct in the conventional fashion is fine.
But, what about the perimeter run? This is where novel ideas are sought.
The best I've come up with so far is wire mesh basket tray. Trunking is out due to high cost, and the excessive derating and grouping factors I'll need to apply will pretty much kill any chance of using "standard" cable sizes. I'm really not up to getting into discussions with the inspector about circuit diversity as a way to reduce the cable sizing, so keeping things simple would be good.
Ideally, it should be possible to tie the cables to maintain gaps between each cable to allow neglible grouping factor (1.00 for a single tray, BS7671:2008 Table 4C4 method 32, max 6 spaced cables). In fact multiple trays would be OK, grouping factors not much worse.
Due to the void containing hot + cold water pipes I will probably have to apply ambient temperature derating - needs more consideration, though I can probably vent the void back into the living space.
A second idea: a poor mans cable tray consisting of a vertically oriented plank of wood running around with cables clipped in horizontal runs and spaced out vertically. Almost conventional then.
Don't really want to do anything too controversial, but - well, what would you do to get neat cabling?
Cheers
Tim