Widget for joining 3-core mains flex

Nor would I pull leads around corners.

I would either replace the lead on the appliance with one long enough for my purpose or use an extension lead fully unwound the get near to the point of use and plug the appliance into the lead.

Where the lead on the appliance is very short say a couple of metres I use an extension lead with a rubber socket on one end and an RCD plug on the other

For the load you describe I would use a 2.5 t&e cable fully unwound

Tony

I don't know of any safe way of making an inline cable joint that will allow the joined cable to be wound neatly on a small diameter drum. As well as providing electrical insulation, the material has to provide strain relief, abrasion resistance, water tighness and a load more.

The nearest thing is probably crimped sleeves used to make offset joints to the wires, with heatshrink tubing insulating individual cores from each other and an adhesive-lined heat-shrink extra-thick outer tube overall. The outer tubing extending far enough along the cables for the adhesive to give strain relief. But that will be much less flexible that the typical continuous cable and the strain relief will be much inferior to that provided by continous cable - particularly if the cable is subject to self, or extrnal, heating. It may be ok for some fixed wiring but certainly is not for cable being wound on a small diameter drum.

If the cables to be joined have clean and uncontaminated rubber outers, self-vulcanising tape can be used in place of, or under, the adhesive-lined outer tube. That will be able to take higher temperatures and still maintain some form of strain relief. But is still far inferior to that required for safety.

The only safe solution is to replace the whole of the two cables with a single one.

Why not just replace the flex with one of the length you want?

NT

But that is about twisted flex joints (the key is in the name :o) ) rather than soldered joints, which is what the OP was talking about. Hardly ideal but still not twisted flex joints and therefore not subject to the dangers described in the article.

On Fri, 01 Jun 2007 09:00:59 +0100, Coleman mused:

New flex with no joins.

I'd only entertain the idea of joining a mains flex if it were with a plug and socket arrangement or soldered\crimped if it were on a piece of equipment that wasn't dragged round corners on regular intervals.

I would suggest that soldered joints covered with normal heat shrink and insulating tape, "lack tensile strength, abrasion resistance, general robustness, spillproofness (they can make a small spill live), good insulation, petproofness & small childproofness."

The marginal advantage of soldering the joints has to be balanced against the greater risk of failing during flexing, as the soldered joint will form a flexure discontinuity and stress points.

Of course, soldering with acid flux would be an even greater problem.

Then you are dangerous beyond belief. You cannot do this - it violates UK regulations.

You must add a socket and a plug to connect the two cables.

Any other joining method will result in potential loss of fire insurance and possible prosecution.

I also thought it was pretty obvious what also applied to soldered joints. Solder is weak stuff too, though I've not seen any significant failures from soldering pretwisted flex (at LV). But not everyone twists enough before soldering.

NT

You can buy Permanent Mains Flex Connectors that don't involve plugs and sockets, eg

"Waterproof" versions are also available, for outdoor use.

These are frowned on in many jurisdictions, however if they are approved in the UK then they can be used there.

Whats the problem with them? Ours all have cord grips.

NT

In the UK portable equipment has to be provided with a fitted plug - in recognition of the fact that many people were incapable of correctly fitting (and fusing) one themselves.

So, what are the chances that one of those will correctly choose and wire one of the above? Or use a non-rugged one outdoors, drag it around corners, let it fall into a bucket of water, etc?

Many (most?) do not have anything to limit the bending radius of the cables at the point of entry close to the fixed cord grip. So strands of the cores break, leading to the risk of fire, failure, etc.

Few are vapour-tight or even water-tight. As the are often dragged around through damp grass, left in the shed, etc - there is a real risk of corrosion..

Bear in mind that a typical application is to "repair" an electric garden tool - where the user has cut the cable...

Replacing the two cables with a single, contiguous, one is by far the best solution.

Or in recognition of the fact that everywhere else in the world gets a fitted plug.

So?

The ones I've seen have cable grip and strain relief at each end similar to that found on plugs

I'd suggest that most things likely to be used in the garden will use the garden tool type of plugs since a ready made extension can be bought for less than the cost of extending the lead.

Maybe. But most garden tools have a plug/socket arrangement at the appliance to make lead changing easy.

That's a safety break, for many reasons. If you drop something like a hedge trimmer, it won't be left dangling around your nuts on the cord looped over your shoulder.

Indeed. Also makes storing the tool easier - or adding an extension. And those extensions with the appliance plug/socket on them often can be bought for less than the cost of the cable from the same store.

Methinks you worry overmuch. I've been doing this for years, although it's solder, adhesive heatshrink (don't forget to put it on *before* soldering the joint), more adhesive heatshrink over the whole thing then insulating tape. OK, it isn't that bendy or pretty, but it'll go on a drum and I've never, ever, had a joint fail, and there's one in the lead for my big mains drill.

Jesus Christ, do you drive? You're about 300 times more likely to die in a car crash. Get a grip.

My recently purchased Bosch trimmer, although it had the inconvenient "needs 2 hands" feature (the reason God created gaffer tape) did not have a plug/socket, making it inconvenient to store. I fitted one.