cable access rods

[Stephen]

Hello,

As you may know from my other threads, I have been wall chasing. I have a house without a hall, so you have to walk through the lounge. The lounge has two doors but only one light switch. So I was hoping to rewire the light to two way switching. The problem is that I need to access three points: the first switch, the second switch, and the light itself. Now due to the layout of the house, each one of these is under a different bedroom. I didn't fancy having to roll-up the carpet in three rooms and lift three sets of floorboards, so I bought a set of cable access rods thinking I could do some keyhole surgery. It hasn't been as easy as I thought. Can anyone give me some pointers on the correct technique?

The Screwfix catalogue says that its po9les can fit through an 8mm hole, of course I need a slightly larger hole for the 3&E! I actually bought mine from Toolstation because they were a few pounds cheaper and had free delivery too.

The rods have to be rigid so that they go where you put them rather than kinking like wire would on its own. But I find their rigidity is a weakness as well as a strength. They are fine for pushing through the hole above the light fitting because there is room to push them from any angle but I find that the poles are too rigid to push up from above the light switches. the wall is in the way so they angle is quite tight and they won't flex sufficiently. I have "solved" this by pulling the rods down rather than pushing them up.

Are there any tricks to make using them easier or do they have their limitations?

Thanks.

[Bob Eager]

I've never actually used them. Opened out coat hangers are rigid, yet flexible, and you can form and re-form the end with pliers. Not necessarily as long, but it is possible to join them...

[Andrew Gabriel]

I've never bought the screw together rods either. I have nylon draw wire, but being a coil, that's useless other than for drawing wires into conduit.

Other things I've used very effectively are for fishing wires through voids...

Expanding tape measures sprung steel waste pipe unblocker mini trunking lids

With the metalic ones, make damn sure there's no chance you'll push them into a live connection.

If you have modern plaster coving around a room, you affectively have a nice piece of trunking there. You can drill through the front with a large flat spade bit, and then draw cable through the void (expanding tape measure works best for this one). If you hit a blockage, drill though to clear it. The holes are easily filled with pollyfila and if the coving is painted white, you probably won't even need to repaint it.

[Appin]

The message from Stephen contains these words:

Those sentences are somewhat confusing. I'm not quite sure why you would be pushing them UP from ABOVE the light switches.

Yes, of course they have their limitations. Different makes and models have different degrees of flexibility, but in general terms they're one of the genuine innovations of recent years and they're a great help. I generally find the skinniest ones are the most useful. These things save hours and hours of time. As with all such things, a mate makes a big difference and can be essential when fishing round corners. Ingenuity goes a long way and there are variations on old tricks that can be adapted for use with these fibreglass rods.

[js.b1]

Essentially you have 3 holes into the underfloor void:

- 2x light switch oval conduit, 1x light ceiling rose

Underfloor void is typically:

- Runs of joists, separated by oblong or X-strap blocking

- Oblong blocking may "occlude" cable rod access if joist offcuts

- Joists may be of differing depth per room depending on span

You need cable access rods &/or cable tape, plus chain & magnet. You need access to the underfloor void "somewhere" - typically the stair landing or box-room or some other small bedroom.

Typically push a short cable rod with loose chain up the conduit or ceiling rose hole so the chain dangles on the plasterboard. Then push lengths of cable rod/tape with magnet on the end along the "duct" formed by the joists/floor/ceiling until you hear the chain snap to the magnet. You may have to twirl the access rods holding the chain. When you hear it snap, unscrew the chain from the access rod & tie on a piece of string, withdraw the other access rods to pull through the string then cable.

Alternatively you could try a flexible cable tape pushed up which eventually makes its way along the ceiling void, this is usually quite difficult - but go with what works with any given situation.

You will probably need to drill holes to "cross" joists from the other light switch.

The only other alternative is to use MK Echo (or similar) wireless light switches & receiver at the ceiling rose, or an occupancy sensor and dispense with conventional light switches (might be buying a spare occupancy sensor if ever going cheap).

There are true "extending fishing rod" access rods which are used in lofts from the loft hatch to feed cable around ceiling rose & oval conduits. They are quite expensive, about =A376, but work incredibly well - you just poke rods with long flexible chain up the ceiling rose/ switch drop and use the rod to snap onto them, typically with end- mounted LED & magnet (double fitment).

Most cable access rod kits lack the flexible open-link chain, but you can make one and open a link to feed it through an "eyelet" fitting on the cable access rod. You need steel chain, not brass, for magnets to work. Glue the magnet if it feels loose, the Silverline ones tend to be quite strong but poorly retained in the fitting (nothing more than a weak interference fit).

Cable access rods do not conform to the same thread standard, do a Google on a previous post. You can also buy "magnet on bendy-rod to handle" - quite useful but the magnet head is too large. Beyond that the next tool is a boroscope camera, such as a USB type or the type with LCD display on the other end (no PC/laptop required). Electricians in a hurry will rip down a ceiling as it is quicker if you have walls on floors or tanks on floors preventing access, only needs some pieces of plasterboard and a skim.

[bof]

In message , Andrew Gabriel writes

I find I use these much more than anything else for running cables, the

1cm wide plastic ones are the best, you can put semi permanent bends in them, make them turn in different directions by twisting them and easily extend them by taping a couple together.

[John Rumm]

A trick here is to make the hole in the ceiling large enough to get a finger + the rod through (sine this is normally directly above the chase, it will be covered when the chase is filled. The trick is to slide your finger up the back of the chase behind the rod. Now you can curl your finger a bit to bend the rod away from the wall in the ceiling void - you should be able to get enough flex to start it off in the right direction. Even if you need to hit it against the underside of the floor above a few times to trap the angle you have got so far, and then release it and apply a bit more deviation each time.

Also you will find many rod sets come with a short (about 3") nylon leader that you can screw onto the rod. This can be pre bent such that it starts the rod deviating in the desired direction when it hits the underside of the floor.

As with all things there are tricks. A little depends on which set of rods you have, and hence what toys to attached to them. Most come with a hook for example - these will let you fish for one rod from the side and pull it towards you. A magnet and chain set makes this even easier. Some of the posher sets have different thickness rods that can be used where extra bend is required.

[Stephen]

I had to have an L-shaped run of wire: across the floor upstairs and down the wall to the light switch. I thought I could do this one of two ways: either across and down working from upstairs, or up and across working from downstairs.

Care to share? ;)

[Stephen]

[mini trunking lids]

Sorry, I can't quite picture what you are doing. Do you mean you take a length of trunking, discard the main body and take the thin top and use that?

[Stephen]

I wondered what that was for. Thanks for all the tips.

[bof]

In message , Stephen writes