ALDI Wall chaser

I'm not quite sure of the purpose of this oval trunking. For most things it's unlikely you could replace a cable or add one at a later date - and if PVC gives no real extra protection to nails, etc, in the wall. I just use a few cable clips and plaster over.

Reply to
Dave Plowman (News)
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Run the conduit/trunking outside, you know its going to be easier.

Why not run SWA?

Reply to
dennis

dennis@home coughed up some electrons that declared:

Yes indeed, but see below.

The thought did occur. Unfortunately theres a doorway in between and no space over the door (bungalow). I did actually consider going down, underground, along and up, which isn't actually a stupid idea, except for this bit:

Currently we have 2 adjacent jewson (meter) boxes. One has meter, other has current CU (don't ask). Both are >3m from the site of the new CU (indoors) though not by much, but being pedantic, I'm going to put a fused-switch in place to abide by DNO rules 'cos I need them to reterminate the tails, so it's better to be by-the-book. If I can get the switch-fuse inside, I can lose the surplus jewson box. One's ugly enough, two are hideous.

Here's a drawing of the best theory to date:

----------------------------------- Ceiling | |**************** | SF | * ------ *

----*---------------------*------- Picture rail * | | * * | | * * | | ------- *Meter | | | | *Outside | DOOR | | CU | * | | ------- | | | | | | | | | | ==================================== Floor

  • = 25mm2 cable runs.

SF = Switch-Fuse

Bottom of the left hand cable run has a 90** degree bend straight through the wall.

Top run can go behind coving, but still needs mechanical protection under the 17th and due to the nature of the circuit, the otherwised required 30mA RCD protection for not having protection isn't viable. The new CU and down run of conduit will be in a 200mm deep full height new wiring cupboard (boxed in with ply). This bit works really well as SWA terminations are done low in the cupboard and go down through the floor and outside for external final circuits (shed, gate lights etc). All the rest of the final circuits go up into the roof void.

With the above, I *should* be able to limit each run to 1 bend, possibly even using a preformed fitting so I've only got the thread cutting to deal with. Might need a second bend on the conduit to meter box depending on whether I'm feeling brave enough to core drill through the back of a populated box or whether I go in the side near the base (coward's method, I like being a coward)

The room is a hallway and utility area, but I'd prefer to avoid surface conduit if possible, except where I can hide it under the coving.

It's all good fun :)

Cheers

Tim

Reply to
Tim S

I've done both, quite easily. It's a bit harder with capping as one side of the channel is rough. However, I managed to draw new wires through all except one piece of the existing capping when rewiring an early 1950's bungalow.

Reply to
Andrew Gabriel

During my last experience of wiring - which, as it happens, was the last time I used my Aldi wall chaser - I used capping which I'd nailed roughly into place (not very well) just to support it while the plastering was done.

The plasterer came and did his stuff in my absence, and later on when I came to test the wiring I found a short in that cable drop (ie between ceiling and socket) and I ended up just taking that socket out of the ring altogether rather than trying to get fresh cable to that socket). I'm convinced that the plasterer must have bashed another nail through the capping to hold it better in place, and caught a cable in doing so (I sure as hell didn't do so myself!).

Anyway, that's another vote for oval trunking next time I have to do it!

David

Reply to
Lobster

Could you run SWA outside over the door, and conceal it (and the areas of wall made good post-removal of "jewson boxes") with some trellis and climbing plants?

Owain

Reply to
Owain

Owain coughed up some electrons that declared:

Hi,

Unfortunately, there isn't an "over the door" as such - the soffits are more or less level with the top. I'll see if there's any clearance above the soffit boards (they need to come off anyway). Might be able to notch out their supports a bit. Worth a look.

Cheers

Tim

Reply to
Tim S

I was just going to suggest taking the soffits off. The rafters/trusses shouldn't be structural at that point (assuming there are no joint plates) so you can drill quite large holes to thread SWA through. You can probably just run it in the attic without cutting anything. If so fix it to the underside of the roof so it doesn't get covered by insulation, then you don't have to de-rate.

Reply to
dennis

Unless things have changed,whenn using steel conduit all cores of an AC circuit should run within the same conduit to cancel out the magnetic field to prevent eddy currents in the steelwork.

Reply to
<me9

snipped-for-privacy@privacy.net coughed up some electrons that declared:

You're right about the eddy currents, which is why I would be forced to use

32mm steel for me meter tails (11mm outside diameter for double insulated tails, not quite fit in 25mm).

But methinks you may have missed the context:

Cable != wire, conduit = plastic oval, not steel (that'll be the other branch of this thread thread I'm wittering in, re meter tails)

and this is what I meant:

=== is oval conduit, on a ring or radial socket circuit: Conduit contains exactly 1 twin+earth cable

Socket ==================================== Socket ^^^ Sink new box here to get

Socket ============== Socket ============== Socket

One cable, each half. It's probably not going to ever be necessary if one installs enough sockets to start with, but, well...

The original point was, that if you do this, you don't get enough spare cable to terminate to the new middle socket. But with oval (any) conduit you do get to pull new bits in.

Never mind, it was a silly point anyway. :-O

Cheers

Tim

Reply to
Tim S

I was under the impression that it /was/ for meter tails buried in a wall, and thus needing more protection than plastic would give. Perhaps I got my threads crossed.

Reply to
<me9

snipped-for-privacy@privacy.net coughed up some electrons that declared:

This thread's rather gone off on several tangents. We've got oval conduit, meter tails and general wall chasing. The only thing that's not here is Dribble, he's busy marvelling at ALDI plumbing tools

;->

Reply to
Tim S

Somehow I had the idea that it was verboten to bury meter tails in a wall - they obviously can pass through a wall however, as they do here. The meter is 'outside' in a Permali box and the CU's inboard of it.

Reply to
Frank Erskine

In my ignorance, what would be the outcome of getting eddy currents in my steelwork?

David

Reply to
Lobster

I've only seen it once where there were two steel conduits feeding a multiple switch plate which included neons as tell tales, and a 'tidy' sparks had run all the feeds down one conduit and returns down the other. The conduit got hot. So it is wasting electricity at best.

Reply to
Dave Plowman (News)

Lobster coughed up some electrons that declared:

As you know, current down a wire produces a magnetic field and AC makes for alternating magnetic field.

Alternating magnetic field and induce current in conductors, and the effect is *much* stronger if magnetic (eg ferrous) materials are involved.

Normally, none of this is a problem if all phases and the return neutral of a circuit are contained together because the sum of the magnetic field is zero. So for single phase, L+N should always run through the same aperture in any ferrous enclosure, including pipe. This includes entry holes in equipment too, though the issue can be mitigated by cutting a thin slot between two adjacent holes and using them.

The final effect of strong alternating magnetic fields is induced alternating current in the steel pipe or whatever, which working against the resistance of the material produces, as someone else said, heat.

Cheers Tim

Reply to
Tim S

It adds unwanted impedance in the circuit increases voltage drop. It can interfere with motor starting, especially for motors which have to start on load and will stall if there is insufficient starting torque. Where line and CPC paths are separated in this way the earth fault loop impedance could become too high to ensure that overcurrent protective devices operate to clear an earth fault, leading to a serious fire risk.

So it's a complete and utter no-no.

Reply to
Andy Wade

dennis@home coughed up some electrons that declared:

Good news for me. Done a bit more investigation. Upon making a hole in the soffitts, I can see the inner leaf of the wall. It stands about a foot higher than the outer leaf and seems clear of obstructions on the cavity-side face.

I think I've found the place to clip either cable or conduit.

I could probably argue that I could run tails without mechanical protection as they would be > 50mm from the face of the wall (that's wall, not leaf). Technically they are not in the cavity either, they are over it.

But I would probably use protection anyway, though steel trunking would also be viable.

So, I can manage a fused switch in a 2nd meter box, conduit, trunking or SWA to CU. Or fused switch above picture rail, tails straight in through the back. Conduit would require 2 90 bends, so use fittings.

Well, down to a couple of sensible arrangements now. And either would work.

Cheers for all the ideas etc.

Tim

Reply to
Tim S

PS

Don't forget it's 8kg SDS+ and core drills day at ALDI today!

Reply to
Tim S

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