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3 minutes ago, Tracy D'arth said:

I try to get the strands well twisted together and then double them back on themselves so that the connection is full of wire before tightening the screws. Then go over the screws again before you finish.

 

Never has a burnt connection like the one shown doing it this way, or with solder.

 

I remember when copper was in short supply, after Rhodesia became independent I think, and we had to use aluminium cables for mains wiring. The existing accessories with one screw were not good at getting a solid connection and the aluminium  was brittle, snapped off easily where the screw bit into the conductor if stressed.

A range of accessories with clamp plate connections were made, like CU MCBs are now, much better connections.

Quicker to fit a ferrule.

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33 minutes ago, Tracy D'arth said:

I do understand the use of ferrules on flex cable connections but how ever did we survive a whole 2 centuries not using them?

 

33 minutes ago, Tracy D'arth said:

 

 

 

As a lad we ALWAYS fitted MK plug tops. They came with a threaded post and a captive washer to clamp the flex. but every lamp holder, ceiling rose etc had holes and screws

Edit

Just seen Loddon's post

Edited by ditchcrawler
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5 minutes ago, Loddon said:

 

MK used to produce 13amp plugs that could be considered suitable for stranded cable (pic below) but they are a pain to wire neatly, not sure if they still do.

Tinning is a last resort.

 

 

MK-BS1363_13_Amp_White_Fused_plug_inside.jpg

The best plug top ever made, with many great features - one of the best being that all the cores are cut to the same length!

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4 minutes ago, Loddon said:

Most people don't know what Speakons are ?

I had to go and look at one in the workshop to remind myself of the clamping arrangement the flange makes all the difference ?

MK used to produce 13amp plugs that could be considered suitable for stranded cable (pic below) but they are a pain to wire neatly, not sure if they still do.

Tinning is a last resort.

 

 

MK-BS1363_13_Amp_White_Fused_plug_inside.jpg

These MK plugs are long gone sadly, a good design. though I was not too fond of the plastic strain relief inserts. They were better than the scruffy bit of fibre and 2 screws though.

The earlier one with separate washers was a pain, frequently dropped a washer.

The plastic reversible clamp now used is much better, able to grip thin and thick cable equally well.

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24 minutes ago, Loddon said:

Most people don't know what Speakons are ?

I had to go and look at one in the workshop to remind myself of the clamping arrangement the flange makes all the difference ?

MK used to produce 13amp plugs that could be considered suitable for stranded cable (pic below) but they are a pain to wire neatly, not sure if they still do.

Tinning is a last resort.

 

ETA I started in the Audio industry in the days when the  EP series were the standard speaker connections before Speakon was invented?

 

 

MK-BS1363_13_Amp_White_Fused_plug_inside.jpg

Those MK plugs had a horrible habit -- when wired up by careless people  -- of allowing one fine strand of wire to end up free instead of clamped down, with amusing consequences...

 

Before EPs became popular (and afterwards) XLRs were all the rage, again leading to amusing incidents when speaker and mic cables use the same connector. And before that (or when XLRs were too expensive for some people) it was all 1/4" jacks, even more amusing... ?

Edited by IanD
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50 minutes ago, IanD said:

Others would indeed disagree because solder creeps under stress and runs away from the load, so the terminals work loose again -- in fact this is probably worse than using stranded copper wire...

 

I've seen this happen on multiple occasions with things like high-power speaker leads, though I haven't seen anyone mad enough to do it with mains...

We will agree to disagree 

Plenty of suppliers of mains equipment are happy to send pre tinned ends on their flex and many of the ferrule suppliers say Crimp or lightly solder...

 

Im not saying soldering (and I mean light tinning) is best or worst just something that might help the OP

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5 minutes ago, IanD said:

Those MK plugs had a horrible habit -- when wired up by careless people  -- of allowing one fine strand of wire to end up free instead of clamped down, with amusing consequences...

 

Before EPs became popular (and afterwards) XLRs were all the rage, again leading to amusing incidents when speaker and mic cables use the same connector. And before that (or when XLRs were too expensive for some people) it was all 1/4" jacks, even more amusing... ?

I started in 1969 so well remember that era, there are countless stories that I have forgotten ?

Metal clad Hubbel connectors for mains were fun if the screws came loose, it hurt.

I remember the days before Switchcraft  when only Cannon XLR were available in the UK, at least there were no screw connections.

 

As for the MK plugs it appears they are still available

https://cpc.farnell.com/mk/646whi/13a-safety-plug/dp/PL00465?st=mk 13a plugs#anchorTechnicalDOCS

I looked at the tech docs and it shows the old style although it says the screws are captive making it harder to wire ?

9 minutes ago, jonathanA said:

Im not saying soldering (and I mean light tinning) is best or worst just something that might help the OP

They will struggle to solder that cable with the amount of oxidation that has happened.

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37 minutes ago, Tracy D'arth said:

Only if you have one the correct size, wrong size crimps are worse than nothing at all.

 

Boat AC wiring tends to be the 2.5mm2 'arctic' cable so you only need one size, not difficult to get a bag of them and 'have enough for life'.

 

£11 for 100. You only do the job once.

 

100 x RS PRO Crimp Bootlace Ferrule, 10mm Pin Length, 2.6mm Pin Diameter, 2.5mm² | eBay

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15 minutes ago, Alan de Enfield said:

 

Boat AC wiring tends to be the 2.5mm2 'arctic' cable so you only need one size, not difficult to get a bag of them and 'have enough for life'.

 

£11 for 100. You only do the job once.

 

100 x RS PRO Crimp Bootlace Ferrule, 10mm Pin Length, 2.6mm Pin Diameter, 2.5mm² | eBay

86p from CPC as mentioned by me at the start of this thread ?

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1 hour ago, jonathanA said:

We will agree to disagree 

Plenty of suppliers of mains equipment are happy to send pre tinned ends on their flex and many of the ferrule suppliers say Crimp or lightly solder...

 

Im not saying soldering (and I mean light tinning) is best or worst just something that might help the OP

I don't think we're disagreeing here -- tinning *of strands* is not [see later post] OK, solder *inside* a ferrule is OK.

 

What isn't OK is what many people think "solder" means, which is turn the separate strands into a single copper/solder strand, where the rigidity comes from the solder.

 

Put this into a terminal and tighten the screw down as much as you want, if you come back months or years later (or even days...) it won't be tight any more. Or if you're unlucky you'll have a scorched mess, or even a fire.

 

Seen this more times than I've had hot dinners...

Edited by IanD
correction about tinning
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1 hour ago, Tracy D'arth said:

Only if you have one the correct size, wrong size crimps are worse than nothing at all.

If you dont carry a select of various terminals and ferrules as any good boater should have on board.  

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39 minutes ago, Keith M said:

Dont forget that the IET regulations are for only domestic installation, not marine.

So what do the equivalent regulations for marine say?

 

The creep risk is exactly the same -- in fact worse if anything, since some bits of boats are hotter than most things in houses -- so I'd expect a similar rule.

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Interestingly when I worked Offshore all terminations back to distribution board were via Klippon Terminals which are saddled to securely hold all cable strands.https://www.weidmuller.co.uk/en/products/connectivity/terminal_blocks/screw_connection.jsp

The cable was 7 strand armoured cable so thicker conductors than flex, perfectly matched to the connectors in fact. However one installation carried out in the latter years insisted in using crimp connectors on the ends of all cables so introducing another point of failure. 

Screw connection with clamping yoke technology

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