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Three Phase Flex - two black cores?

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DNS1

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Hi chaps,

Spent today repairing a load of 63A and 125A three phase flexes.

When taking the damaged plugs off I was somewhat surprised to find that two of the cores were the same colour...

Can anyone explain why I've got two black cores and one brown? I was expecting to find black, brown and grey...
 
Hi chaps,

Spent today repairing a load of 63A and 125A three phase flexes.

When taking the damaged plugs off I was somewhat surprised to find that two of the cores were the same colour...

Can anyone explain why I've got two black cores and one brown? I was expecting to find black, brown and grey...

Are the cores marked L1,L2 L3 and id the machine American?
 
That's the point I'm making, you can't identify the cores without a continuity tester which seems really odd!

I have worked with cables like the ones you are on about, sometimes you are supplied with cable like this, yes an initial problem but 5 mins with a continuity meter job done.
 
Were the machines old soviet stuff. I worked with a slovakian several years ago and he was telling me the old ussr machines would have 2 black cores and both were lives.

This is just spmething i was told and i in no way stand over above statement lol
 
usually they have numbers on that are hard to see, it might be further down the cores than you can see.

or maybe not, a friend bought some twin that was brn,brn.

he only knew which was which because he used the top as one and bottom as two (using the manufacturer's markings on sheath)
 
Yes a lot of older black rubber flex has two identical black cores in it, I think it is a relic of the days when electricians were taught to use their brains.

We've got a fair amount of it in our hire stock of 63A and 125A extension cables.
 
usually they have numbers on that are hard to see, it might be further down the cores than you can see.

or maybe not, a friend bought some twin that was brn,brn.

he only knew which was which because he used the top as one and bottom as two (using the manufacturer's markings on sheath)

Twin brown is hardly a novelty. It is for your strappers in a two way lighting cicuit
 
Sometimes I'm also convinced it's where the dye process has just made the grey too dark. Like Tel says, in the dark you don't stand a chance!
 
Brown/black/black was standard in a number of EU countries before harmonisation and a lot of EU-made flex had those colours. If you look into the end of the cable the three lines will usually be laid up together and I always wire them so that they run in order i.e. L2 is the black next to L1 brown. The advantage of these colours, if you like to cheat, is that you know which is L1 and you can arrange the other two to suit, to make your machine go the right way!

I'm surprised so few people have seen it. Like Davesparks I've had miles through my hands and it was bog standard until 2004.
 
I've see it a few times but never realised it was an EU standard at one time or other. Like Rockingit I also thought it might be the dying process making the gray too dark to distinguish from the black but never got around to looking into it any further.
 
Read the previous posts and you might realise

The only time you have to "bell out a twin brown" would be at multiple switch positions, hardly a big job is it better than fiddling around with bits of sleeving, or tape in some cases, people will be wanting twin brown labled Line and Switch line next.
 

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