Widget for joining 3-core mains flex

[Coleman]

I am in the UK. I want to ask for info about joining 3-core mains
flex on an appliance that may have to carry up to 3,000 Watts.

I usually extend the mains flex by soldering but the finished join is
too bulky when winding the flex or pulling it around a corner.

When I make my 3 joints I slightly offset each one so that it is not
beside another one. This helps make a slimmer overall joint but it
makes for a longer joint (about 2.5 to 3 inches) and with insulating
tape it is still too bulky.

(A) Is it safe to use heat shrink insulating tubing for each join
and have each join beside the other? Then I might use a single layer
of insulating tape to bind over and protect the 3 joins.

(B) Or is there some widget which can help with this? Perhaps a
small moulding which is made up of three very small metal tubes held
by moulded plastic to be close together but not touching. I could
put a wire into each end of a metal tube and then solder the wires
into it. (It's just an idea.)

Any info?

 

[TMC]

I am in the UK. I want to ask for info about joining 3-core mains
flex on an appliance that may have to carry up to 3,000 Watts.

I usually extend the mains flex by soldering but the finished join is
too bulky when winding the flex or pulling it around a corner.

When I make my 3 joints I slightly offset each one so that it is not
beside another one. This helps make a slimmer overall joint but it
makes for a longer joint (about 2.5 to 3 inches) and with insulating
tape it is still too bulky.

(A) Is it safe to use heat shrink insulating tubing for each join
and have each join beside the other? Then I might use a single layer
of insulating tape to bind over and protect the 3 joins.

(B) Or is there some widget which can help with this? Perhaps a
small moulding which is made up of three very small metal tubes held
by moulded plastic to be close together but not touching. I could
put a wire into each end of a metal tube and then solder the wires
into it. (It's just an idea.)

Any info?

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

[max4: uk.diy alt.e.e. sci.e.e. sci.e.c.]

 

[Palindrome]

I am in the UK. I want to ask for info about joining 3-core mains
flex on an appliance that may have to carry up to 3,000 Watts.

I usually extend the mains flex by soldering but the finished join is
too bulky when winding the flex or pulling it around a corner.

When I make my 3 joints I slightly offset each one so that it is not
beside another one. This helps make a slimmer overall joint but it
makes for a longer joint (about 2.5 to 3 inches) and with insulating
tape it is still too bulky.

(A) Is it safe to use heat shrink insulating tubing for each join
and have each join beside the other? Then I might use a single layer
of insulating tape to bind over and protect the 3 joins.

(B) Or is there some widget which can help with this? Perhaps a
small moulding which is made up of three very small metal tubes held
by moulded plastic to be close together but not touching. I could
put a wire into each end of a metal tube and then solder the wires
into it. (It's just an idea.)

Any info?

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.

 

[Dave Plowman (News)]

I am in the UK. I want to ask for info about joining 3-core mains
flex on an appliance that may have to carry up to 3,000 Watts.

I usually extend the mains flex by soldering but the finished join is
too bulky when winding the flex or pulling it around a corner.

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

 

[[email protected]]

I am in the UK. I want to ask for info about joining 3-core mains
flex on an appliance that may have to carry up to 3,000 Watts.

I usually extend the mains flex by soldering but the finished join is
too bulky when winding the flex or pulling it around a corner.

When I make my 3 joints I slightly offset each one so that it is not
beside another one. This helps make a slimmer overall joint but it
makes for a longer joint (about 2.5 to 3 inches) and with insulating
tape it is still too bulky.

(A) Is it safe to use heat shrink insulating tubing for each join
and have each join beside the other? Then I might use a single layer
of insulating tape to bind over and protect the 3 joins.

(B) Or is there some widget which can help with this? Perhaps a
small moulding which is made up of three very small metal tubes held
by moulded plastic to be close together but not touching. I could
put a wire into each end of a metal tube and then solder the wires
into it. (It's just an idea.)

Any info?

http://wiki.diyfaq.org.uk/index.php?title=Twisted_Flex_Joints

NT

 

[Bob Mannix]

http://wiki.diyfaq.org.uk/index.php?title=Twisted_Flex_Joints

But that is about twisted flex joints (the key is in the name ) ) 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.

 

[Lurch]

I am in the UK. I want to ask for info about joining 3-core mains
flex on an appliance that may have to carry up to 3,000 Watts.

I usually extend the mains flex by soldering but the finished join is
too bulky when winding the flex or pulling it around a corner.

When I make my 3 joints I slightly offset each one so that it is not
beside another one. This helps make a slimmer overall joint but it
makes for a longer joint (about 2.5 to 3 inches) and with insulating
tape it is still too bulky.

(A) Is it safe to use heat shrink insulating tubing for each join
and have each join beside the other? Then I might use a single layer
of insulating tape to bind over and protect the 3 joins.

(B) Or is there some widget which can help with this? Perhaps a
small moulding which is made up of three very small metal tubes held
by moulded plastic to be close together but not touching. I could
put a wire into each end of a metal tube and then solder the wires
into it. (It's just an idea.)

Any info?

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.

 

[Palindrome]

But that is about twisted flex joints (the key is in the name ) ) 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.

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.

 

[Homer J Simpson]

I usually extend the mains flex by soldering but the finished join is
too bulky when winding the flex or pulling it around a corner.

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.

Why do you need such a long cable?

 

[[email protected]]

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.

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

 

[Palindrome]

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.

You can buy Permanent Mains Flex Connectors that don't involve plugs and
sockets, eg http://www.maplin.co.uk/images/Full/VJ81C_VJ82D.jpg

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

 

[Homer J Simpson]

You can buy Permanent Mains Flex Connectors that don't involve plugs and
sockets, eg http://www.maplin.co.uk/images/Full/VJ81C_VJ82D.jpg

"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.


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[[email protected]]

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

 

[Palindrome]

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

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.

 

[Dave Plowman (News)]

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.

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

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?
So?

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.

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

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..

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.

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

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

 

[Andrew Gabriel]

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.

 

[Dave Plowman (News)]

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.

 

[Huge]

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."

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.

 

[Huge]

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.

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

 

[Huge]

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.

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.