House needs a rewire, as does the workshop. Now that the price of copper has fallen a bit, it's time to start work 8-)
Any advice on estimating this?
Both cables & sundries, but obviously cable lengths are the first thing. The number of conduit saddles in the workshop is hardly a major budget item, but it's still a pain to run out at the weekend.
As the workshop is going to be in 20mm PVC conduit, is there anything to choose between running single wires, or T&E ? T&E is cheaper (about the same as two cores), presumably owing to the greater sales.
I played the game of installing the ring circuits without cutting the conductors, which meant making sure I bought a long enough reel to do the whole ring in one piece. Not something I would advocate unless you like a challenge or are OCD on perfection;-)
I didn't worry about buying too much (although it wasn't expensive back then). I tend to keep stocks of leftovers, which are often useful later on.
Singles are much easier in conduit. I was about to say you probably wouldn't get 2 T&E's in a 20mm conduit, but I just tried and you can. Wouldn't like to pull it any distance or around corners though, and you'd have to pull both in togther in one go (although you're supposed to do that with singles too, to reduce risk of damage).
I have got a full bill of materials list for my garage and workshop, plus also a 3 bed semi rewire I did fir the previous neighbour if it helps. Got circuit topology diagrams in Visio as well (could export to a image file probably)
The workshop I have got now was in 20mm conduit. I scrapped most of that and did flush mount in the lining. (the previous owners idea of adequate sockets as something like 3 doubles). I stuck about 14 doubles in there IIRC.
Singles are easier to thread round corners etc. Having said that, if you are using inspection elbows then T&E is not too difficult.
For the cables, bite the bullet and pace it all out. For the accessories, do drawings showing locations of all accessories and take a bill of materials from same. For sundries, don't sweat it.
Depending on the size of your house and the extravagance of your wiring, you'll probably end up needing 100-200m of 1.5 T&E, 100-200m of 2.5 T&E and 50-100m of 1.5 3&E.
Everything else (cooker, shower, bonding, tails, etc) buy as cut lengths (unless you get close to 50m or 100m), but be generous in your estimates.
I'd be interested in those to see how it ought to be done (a.k.a plagiarise shamelessly). Can you please drop the Visio files somewhere or mail them to me at usenet{AT}robinwillis.com?
Lighting in 1.5mm^2 or 1? I can see 1.5 for some runs to a whole floor, but not for every individual switch. Even the big workshop lights, 250W SON-Es (I have dozens of the things, from an auction years ago), are only pulling 1A per circuit.
What's with all the 3+E, as opposed to 2 reds/browns+E ? I've a couple of two-ways to do on the stairs, but otherwise I was expecting to be using more of the 2 phase+E than 3+E. Are you pulling this down to every switch as standard?
Andy Dingley coughed up some electrons that declared:
I'm running a mixture. 10mm2 T+E will not fit in 20mm conduit and 25mm is a bit too much wall chasing. So I'm running my cooker and heating (which has
9kW electric backup) in singles in conduit - but the runs are fairly direct. The rest in T+E. I will probably do my roof void inspection lamps in conduit and singles as it's easier to support a bot of conduit overhead between rafters than dangle T+E where it might get damaged.
For 1.5mm2 and 2.5mm2 I would just get 100m reels. When that runs out (and it will) take a guess at a 50m reel or whether you are so close to finishing that a cut length is better.
Gilflex conduit from
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is dirt cheap. Used some today. The difference between it and MK Egatube (which they also sell for much more dosh) is the quality of the plastic. Gilflex is slightly rough, Egatube is smooth and shiney. However, both seem strong, solvent weld and bend OK (though bending did handle differently).
For shoving in a wall or roof spaces, Gilflex should be fine. For better presentation, I think I would by Egatube or some other "better" brand.
Get a conduit bending spring (or any bending spring about the right size) - no need for swept bends unless you need an inspection type, it bends easily by hand.
For overall estimation, I started with TLC's website
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and priced everything off there - they have most common stuff, and though the prices can be bettered, their not outrageous for an estimate.
Thanks. I finally got around to looking at them this morning. Helpful. And I was comforted to see that even you had not rattled off plans, 2 elevations and an overview with perspective :)
Realised my only real question is buying 50m vs. 100m rolls. I don't save by buying more, I won't be buying cut lengths for anything except shower cabling. I won't pull more than 50m of cable in a day anyway.
Then I get to TLC and find they only have 100m rolls anyway, and they "don't get much call" for twin-brown 2P+E (!?) so it looks like all the switches will be run back to their loopins as 3+E anyway.
I must admit I never bother buying small reels (for common sizes) - you always find a use for any leftovers in time.
Quite often when I internet order form them, they spend a couple of days shuffling stuff to the local branch from others it seems. That suggests that turning up on the door hoping for less common stuff may leave you disappointed more often than not.
I've found that internet ordering (for collection from you local branch) takes longer that getting the branch to do it for you. Most things I seem to want they'll have in stock and get those not usually by the next day. Internet orders seem to take 2-3 days to get there.
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