Protecting cables running on top of and across joists

[Makeitgo]

Hi All

I have a bungalow loft whose main pitched roof is of Purlin type, with 4 x 2 joists running at 90° to rafters. As the Joists are 4 x 2 it seems that the 1mm and 1.3mm lighting T+E cables have been run over or round joists rather than through.

I’m thinking the reason was the installer wanted to avoid drilling a cable hole through joists as they are (4”) 100mm deep. Guess you wouldn’t be able to drill that would be < 50mm from the top or bottom of the joist (as per regs?).

The attached picture (with red arrow) is the worst case of cables being vulnerable (bridging multiple joists so susceptible to being trod on) and I was wondering how this should be dealt with.

Do you screw some timber between joists that’s below the top of the joist, then clip the cable to that, so that it’s not so proud and it’s also supported? I’ve looked online and can’t see any examples of how this is done (what the consensus is).

Also, if some of the “clipped to the top” cables have to stay, I’ve seen “Safeplates” you can buy to cover the cable but the joist still needs to be notched using these. As I understand it, notching is also a no no with 4 x 2 joists.

My goal is to board the loft to use for light storage, so it would be good to have a reasonably level base to start with. I don’t really have to screw 2 x 1 (or thinner) sawn timber to the tops of all the joists leaving gaps for the cables do I?

I’ve included more photos showing the general state of the cabling which surprised the carp out of me when I first saw it

I would welcome any thoughts with open arms, cheers guys.

 

[Adam_151]

The installer is quite right that roof joists should not be drilled or notched, however it does look a bit untidy/vulnerable, normally youd clip along the side of joints and then go onto the purlins(?) to get across from one to another or go at the ends, it looks like that nature of the building hasn't presented a lot of options.

Although if you are insulaing and boarding, haven't you got to run some more joists perpendicular to the existing ones in order to get a reasonable amount of insulation in?

 

[Makeitgo]

Thanks for confirming about the drilling and notching. You’re right, the building doesn’t present a lot of options, but wow.. OK, purlins, maybe.

Currently there’s only 100mm of insu in the joists, so I was going to do perpendicular timbers that might take it up to a couple of more inches, but as the rafters have none, I was thinking about using Celotex between rafter to make up the difference. It would just be good get this all tidy to some degree before proceeding.