Discuss TRAINEE QUESTION: Three phase motor system, non-standard wiring colours in flex? in the Electrical Forum area at ElectriciansForums.net

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sijmit

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Hi.

Just a question from a slightly confused trainee about core colours on a three phase appliance.

I was diagnosing a fault on a three-phase saw today (found it - dead isolating transformer) and found that the incoming cable (4 cores) were coloured and connected as such:

L1 Brown
L2 Black
L3 Blue
E Green/Yellow

I didn't look at the saw motor itself but made the assumption that it did not need a neutral (N terminal at the contactor was disconnected). Therefore I would expect Brown, Black, Grey and Earth. I'd only expect a blue in a TP+N system and would expect a grey core in addition in that system too.

Why is this cable coloured like this? Apologies if this is obvious to most, I am only learning at the moment but fascinated. If it helps, the saw isn't new but uses lots of Chinese components internally so I guess isn't that old.
 
Hi.

Just a question from a slightly confused trainee about core colours on a three phase appliance.

I was diagnosing a fault on a three-phase saw today (found it - dead isolating transformer) and found that the incoming cable (4 cores) were coloured and connected as such:

L1 Brown
L2 Black
L3 Blue
E Green/Yellow

I didn't look at the saw motor itself but made the assumption that it did not need a neutral (N terminal at the contactor was disconnected). Therefore I would expect Brown, Black, Grey and Earth. I'd only expect a blue in a TP+N system and would expect a grey core in addition in that system too.

Why is this cable coloured like this? Apologies if this is obvious to most, I am only learning at the moment but fascinated. If it helps, the saw isn't new but uses lots of Chinese components internally so I guess isn't that old.

Welcome to the forum :)

This probably answers your query - its china at its best selling cheap gear into the EU market that fails to comply to the LV directive be it just a cosmetic issue as you have mentioned or worse.
 
Welcome to the forum :)

This probably answers your query - its china at its best selling cheap gear into the EU market that fails to comply to the LV directive be it just a cosmetic issue as you have mentioned or worse.

I did think that might be the case. The customer said that the company he bought the saw off weren't very organised or helpful - which could still be a British company I suppose - but I wondered it had been imported from China.
 
I think the old core colours on a four core flexible cable to BS6500 were brown, blue, black, green/yellow. So if it was flex incoming this may have been correct.
I think some flexible cable still comes in those colours; just having a look at some websites for flex most state the core colours as brown, black, grey, green/yellow but the pictures still show brown, blue, black.
 
It's possible to get brown, black, and blue cable though isn't it - like this image:

TRAINEE QUESTION: Three phase motor system, non-standard wiring colours in flex? 6944X.JPG - EletriciansForums.net

I thought the reason you could get it is for domestic uses such as extractor fans etc.
 
Brown/black/blue 3 core + earth flex was standard for years, until harmonisation in 2004-2006. Most European countries previously used some combination of browns and blacks for lines, but it was understood that if only one core was black, the blue would be a line. There's still enough of it around that I don't notice when I encounter it.

It's possible to get brown, black, and blue cable though isn't it - like this image:

Agree with Pete that's red/yellow/blue/black.
 

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