Easiest way to surface mount cables on hard wall

[David]

I will be reworking the electrics in my Dad's double-length garage, because they are currently a bit of a mess. I'll be installing a ring in 2.5mm sq. twin and earth with maybe six double sockets, and a lighting circuit in 1.0mm sq. Probably an additional radial circuit or two too. There is already a modern garage CU installed, but I'll be moving that. I'm minded to use metalclad accessories.

My concern is that the brick walls seem really hard (it's quite an old building), and I don't relish hammering in hundreds of cable clips. What would people advise for ease of installation (and adherence to regs)? I'm open to suggestions, but lack practical experience with alternatives:

a. Using round (PVC) trunking, with a minimum number of screwed-in saddle clips? I've not used trunking before, but it would look the business I think... b. Clipped direct, but with some kind of clips that are hammered in to drilled holes? c. Extra-tough nail-in clips? Any recommendations? d. Something else?

I've read the

Wiki page. Thanks for your help!

David

[Clive Arthur]

I've used 'nail plugs' with standard cable clips with good results. A long time ago, they're like this...

[Harry Bloomfield, Esq.]

David explained on 26/10/2021 :

Fix wood laths long the walls, where you need to run cables, then you can clip where is suits you. Fix the laths (1/2" thick x wide enough) with screws and plugs to the wall.

[Theo]

If you're using metalclad sockets, any reason why metal conduit isn't on the list?

Easy attachment with saddle clamps. A bit more annoying to cut than PVC, but more resistant to dust, damage, UV, etc.

I've not used it myself, but would seem to be a tidier aesthetic than bare cable clips.

Theo

[Chris Green]

Remember that as of recent revisions cable clipping must be fireproof so your trunking + (metal) saddle clips would be OK as long as the screws are in fireproof (i.e. also metal) wall plugs.

I'd personally advise against any ring circuit, two radials wired in

2.5sq mm are simpler, safer and much easier to modify and extend.

[Chris Green]

Won't comply with latest regulations for fireproof cable fixings I don't think.

[Chris Green]

Not fireproof.

[Theo]

This is an outbuilding not a residence - I didn't think the metal cable clips requirement applied there? Although if it's attached to the house then it might be needed (eg a risk of falling cables blocking a route of egress from the house).

+1. A ring in a garage doesn't buy you very much.

Theo

[The Natural Philosopher]

rectangular plastic trunking glued on with whatever 'sticks like shit' glue is currently fashionable?

[Robin]

or with hard bricks just fit the saddles with concrete screws

[David]

I didn't know an outbuilding doesn't necessarily need fireproof clipping - I'll check.

Dad has a massive oil-filled Oxford arc welder (with a 13A plug on its flex), so when he's using that in the winter with a 2kW fan heater to stay warm, I guessing that would likely trip a 16A MCB on a single radial circuit. Whereas a ring with a 32A MCB isn't going to trip. And I think the cables wouldn't be overloaded, even if they were in conduit.

[John Rumm]

Well one easy option is a SDS drill with a 5.5mm bit, and box of pin plugs:

Drill hole, pop plug in hole, and drive the nail into the plug.

Trunking or conduit?

Either will work, and offer some protection the cables. Conduit is easier to wire with singles rather than T&E. Significantly more work than clipped direct T&E though.

Much depends on how much mechanical protection you need.

Conduit works well with surface mount metal clad sockets etc. Unless you really need maximum physical protection the heavy wall plastic conduit is easier to work than steel.

See above

Some clips have masonry nails. The Tower branded ones from TLC have toughened nails and will penetrate some masonry.

[John Rumm]

Sprinkle in a few of:

Depends on layout - not much in it in many cases.

Why?

Less fault tolerant...

Not convinced.

Also keep in mind that using 2.5mm^2 radials means dropping the MCB to

20A. Not in itself usually a problem but if lots of tools are in use you might need to start thinking about how to loads are spread to avoid nuisance trips.

(e.g. my 3kVA site transformer will regularly trip a 20A type B MCB at switch or, but is fine on a 32A one)

[Dave Plowman (News]

I'd use trunking with a clip on top. Comes in various sizes. You'll need to drill fixing holes, though.

[Dave Plowman (News]

You need to cut and thread it at the sockets, though. But as you say nice and strong for use in a workshop.

[Tricky Dicky]

Trunking and conduit for my garage

I used D-Line clips in the trunking approx. Every 1.2m

Just be careful which trunking you use I used Tower 50X50 which unfortunately has a small ridge for a divider just where the screw for the clip needed to go.

Richard

[Theo]

That looks nice. Is that PVC conduit or metal?

Theo

[newshound]

I've sometimes used those special plastic "rawlplugs" that are designed for cable clips where I have needed to clip to stone or engineering brick. Would they count as sufficiently fireproof in this application?

[Tricky Dicky]

PVC

Richard

[ARW]

Then you should have come to Leicester last year and given me a hand wiring up a reasonably large house using steel conduit:-)

"A bit more annoying" is the understatement of the year.

Bending, threading, cutting, carrying, chasing in in this case.

I have some surface mount stuff to do at HMP Moorlands if you want to give me a hand:-) Obviously not in a cell as surface steel conduit is a ligature point.