Talk:Electrical Installation

From DIYWiki
Jump to navigation Jump to search

Great work guys! Hopefully this is the right place for me to write the following;

I've just gone through with my own minor tweaks & saved them. Below are some suggestions for additions which I don't yet have the time or skill to insert & lay out neatly. Perhaps someone else might approve of them & decide to enter the suggestions themself? They are only in rough form & need re-wording.

  • Mention in the Lifting Floors section that, when lifting boards by prying, it will often 1st be made easier by removing any stubborn nails or screws where possible. Nails or screws with damaged heads that can't be removed even with screw-removing bits, can be drilled down over the top of with a small holesaw of ~10mm diameter, through the full thickness of the board. The board can then be lifted, & the nail or screw with the ~10mm cylinder of wood that it goes through will remain in place. When replacing the board, new screws can be fitted alongside the old positions. <Photo for clarity>
  • When needing to cut access holes in solid/ chipboard, besides the Trend Routabout jig mentioned, one can use a (eg. 110mm diameter) solid board access holesaw, which fits onto drills (widely available inc. on eBay). It has 2 concentric blades which cut a hole with a rebate. The hole can be closed later with corresponding plastic covers which sit on the rebate, perfectly flush with the top of the board. <Photo for clarity>
  • Mention that sometimes larger, hand-hole sized access holes have to be made in hollow/ plasterboard walls (& ceilings). Describe the technique of cutting out a neat rectangle, & then how to patch the hole, involving fitting a short board or similar behind the hole, to create a back surface on which to fit the new piece of replacement plasterboard. <Photo for clarity>
  • Use better, & less photos to show the volt stick in action. (I can't make out what I'm supposed to be seeing in the existing photos!)
  • Include a good torch in the tool list - "very handy". For peering into holes, crawling in attics/cellars, & for when the mains lighting is out! I just love my pocket sized torch with CREE type LED - with floodlight brightness!
  • Include a cable tracker & tone generator kit in the advanced test gear list - "handy". For locating cables behind boards & panels, singling out the correct cable from a bundle of them, & for finding the break in a cable. (Also useful for testing multiple-speaker installations etc). <Photo for clarity>

- Ax

Thanks for the comments Ax. I have included most of them into the article now, plus a few extra bits they prompted me to remember! The volt stick one, yup I see what you mean - I think part of the problem is the model being demo'd is Tim's rather snazzy one with not only live wire detection, but also proximity indication. I may do some photos of my rather more mundane "lights up / beeps when it detects something" one.

Cable tracker etc I will add when I have some suitable photos... --John Rumm 04:43, 13 April 2009 (BST)

Now I'm doubly impressed John - not only with your excellent original article, but also with the speed with which you respond to updates! I could supply my own photos of the new items such as the tracker/ generator, & access holesaw with cover if they're wanted, though I expect that yours or those sourced from elsewhere on the web will be rather better.

If you could do a photo of the holesaw that would be nice. The tone gen/tracker I can do - just requires the enthusiasm to take the camera with me next time I venture to the workshop! ;-) --John Rumm 03:50, 14 April 2009 (BST)

Some minor tweaks for the next revision (not worth creating a new one just for these) include; "cuts a plug of wood from the bard" (Shakespeare?!) Also, I've just checked my plug-removing holesaw, & sorry, it is a "14mm diameter bi-metal" - the 10mm size may be harder to get hold of than I realised. Excuse my ignorance, is the "cf" in "(cf. 10mm)" the latin for "compare" or is it "circumference" - perhaps "diameter" would be better?

it was actually a finger slip - I was intending c. as in "circa" or approx. --John Rumm 03:50, 14 April 2009 (BST)

Addition of snap-off blade knife -"handy or very handy". For stripping sleeving, cutting plasterboard, trimming plastic & general use. Addition of claw hammer "very handy". For cable clips, removing nails, levering floor boards, persuading objects! Other tools could include (but how far do you want to go with the list?); ladder, spirit level (no more wonky fittings!) etc. Not strictly tools, but so useful they deserve to be considered; insulation tape (attaching cable to pull-rods, marking cables & other items, insulation!) & permanent marker pen.

Yup, there is a danger of taking this to extremes, but the marker pen is a non obvious but very useful one I find, after all one bit of T&E can look very much like the other half dozen that you have beside it! --John Rumm 03:50, 14 April 2009 (BST)

When saying "Tools - The following is a big list of tools" should the point be added that it doesn't include tools already mentioned elsewhere? Or should those also be added (pull-rods, board access holesaw, handsaw, jigsaw, padsaw, pry-bar/chisel etc).

probably better to avoid double listing of stuff since it just becomes a pain to maintain. Perhaps a note would be simpler... --John Rumm 03:50, 14 April 2009 (BST)

Finally, this article relates to electrical installations, though thus far it is clearly aimed specifically at Mains electrics. Perhaps this could be clarified, or ideally, at a later date the article widened a little to include a few references to the problems/solutions for the other types of cabling. As well as a little mains wiring, I have done a fair bit of audio/visual & data/telecoms cabling. Whilst mainly for business premises, this is becoming ever-more common in domestic set-ups so may be quite useful to people. Other cables include phone, Cat5e (broadband etc), speaker, video, satellite/aerial, control signals, alarm etc. The basic methods are the same, so nothing much needs changing & I think better to include in this article rather than to produce a whole new one. But some references may need updating, such as; (along the lines of the safety needs being lower, but the signal integrity needs being higher), mechanical protection (& care taken when pulling etc), bending radii (not applicable, or differ), support (staples, clips, ties, spiral wrap, sleeving, under carpet edges etc! - less heat-loss issues), segregation from other cables, tools/test gear (maybe a Cat5 tester, crimper etc).

As you say, much of the technique is the same. There is a [[Low_Voltage_Wiring|LV] wiring article in existence, but beyond listing wire types is relatively content free at the moment. Not sure where the best place to add extra info would be. Oddly things like minimum bend radii are often easier to find for datacomms/av cables than housewiring.
The issue of segregation etc is worth adding a section for. I have added a new bit on cable routing right at the top of the cabling section. Feel free to augment as you see fit. --John Rumm 03:50, 14 April 2009 (BST)

Food for thought! -Ax

Ta for the suggestions - many now included.

As a general point, feel free to make edits to the article yourself - its not "mine", but the collected wisdom of a number of folks - so no one will object. --John Rumm 03:50, 14 April 2009 (BST)

No problem, John. I just didn't want to spoil your "baby" with any large changes - especially since I'm still unfamiliar with the editing & other features found in this site! I'm also aware that too many minor tweaks saved separately make the edit history harder to track should something need to be undone later on. Re the idea of widening the topic to cover all types of cabling, I'd have thought the various differences could just be incorporated where needed as provisos or additions to what's already there.

I've added the access holesaw photo, & managed to keep the filesize pleasingly small.

Keep up the good work! Ax --Wwikidiyfaqq1 17:31, 15 April 2009 (BST) (....just found the sig button!)

FAQ material

Putting it here for now...


By Richard Gethin 25/11/1996

Tie a small piece of cloth to a piece of string and use a vacuum to suck this through the pipe. If the pipe is small you won't need the cloth tied to the end. Then use the string to pull the cable through.


(Can't remember author of next paragraph:Â
Please identify yourself to claim credit! Matthew Marks 7/5/1996)

It can be very difficult to drop a cable down a cavity wall and retrieve it through a small hole into the cavity. Make the hole large enough to feed a loop of old steel measuring tape through it. As you push the tape into the hole, it will expand into a loop along the sides of the cavity. When you dangle the cable approximately above the hole, it will go through the loop, and pulling the tape out will then retrieve the cable.

By John Stumbles 13/5/1996

I'd add that you may be better off going for something easier to manipulate than the cable you want pulled through eventually. I find the sort of plastic-covered springy net curtain rail stuff quite useful for this. Once you've got that through you can use it to pull the cable itself or, if the cable is heavy and/or there's a lot of resistance in the run, pull some strong string or light rope through first. I got some 4 or 5mm polypropylene rope from a camping and climbing shop, and it's quite smooth, strong and moderately stiff. It can help when pulling electrical cable through to lubricate it with something like KY jelly or Vaseline. Other tricks for getting cables through various spaces in buildings (e.g. under floorboards) include 'fishing' with lengths of electrical conduit: this is about 3/4" diameter, comes in 3 metre lengths and is quite flexible. I have a variety of lengths I use for this sort of work. You can feed it into the space under a floor where you have removed one board, and use it to get a string or light rope (e.g. your 4mm polywotsit rope) to another access point. Where you don't have large holes at each end of the run - I recently had to wire under a chipboard floor, and had to cut out one piece of board to get any access at all and didn't want to do that all over the place - then you can get away with one main hole, ideally large enough to stick your head into to see what you are doing, and holes just 6 or 10 mm dia at the other ends. Thread some thin wire or string through the 'fishing' pole with a loop of thin wire at the end:

                     fishing pole (conduit)                 __
wire      ------------------------------------------------ /  \
or -------------------------------------------------------     |
string    ------------------------------------------------ \  /
                                                         wire loop

Dangle some wire (or your 4mm poly cord stuff) down the hole at the other end of the run and fish for it with the pole. A good torch to see under the floor, a light above the small hole, and an assistant to dangle the cord are useful/essential. When you've got the cord through the loop then pull the string/wire at your end of the fishing pole to snare it and you should be able to draw back the pole and cord - then you have a draw-wire to pull cables though with. If keep some thin wire or string tacked up at either end of the run then you'll be able to pull further cables through in future: when you want to pull a new wire through use the keeper string to pull through a stronger drawstring (yer 4mm stuff again) and use that to pull through the new cable and at the same time pull the keeper string back for another day.

When, in a previous job, we had to install wires in the voids above suspended ceilings, over runs many metres long, we sometimes used a crossbow to fire a nylon line down the void, to save having to lift umpteen ceiling tiles along the way. Finding someone to catch the bolt at the other end wasn't easy though ;-)

By Jim Mortimer 16/5/1997

I find that curtain wire, of the type used to hang net curtains on is ideal for this kind of job, as well as a drawstring for running cables or hoses through any complicated route as it's so bendy.

By Richard Gethin 19/11/1998

The lid from 16mm mini trunking is very good for pushing along voids/hooking cables in voids.

By Mungo Henning 16/5/1997

Buy a small length of ferrous chain (like the stuff which would be used in the dog-lead of a small mutt) of about three or four inches long (or long enough to be 'sufficiently' weighty: depends on the quality of the links) and tie it to a bobbin of twine. Drop this down the cavity, having inserted a magnet at the place where you wish to retrieve the cable. With a strong enough magnet, the chain will stick and you will be able to pull the twine through.

I now have an old 35mm-film container which contains the chain connected to the twine, and a separate magnet attached to an old telescopic aerial (neat for the tool-case). Works a treat so long as you don't drop the chain onto Live and Earth!

Another idea is to connect a Lilliput bulb via bulb holder onto some co-ax cable (of the same diameter). Connect the other end to a suitable battery. This helps when you need to see into a cavity hole. The light has been worth its weight in gold over the last few years.