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Old 7th Oct 2017, 9:17 am   #21
Philips210
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Default Re: European Black/Blue Mains Lead

Hi.

Regarding flexible cables fitted to portable appliances, I think in Britain we changed over to the new system in about 1970.
In the old system, the green earth wire is of a much darker green compared to the later green/yellow code. It also seems to have been the same with earth sleeving used for house wiring. Was that standard practice?

I've never seen a mains flex with Red, Black and Green/Yellow wires.

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Old 7th Oct 2017, 9:50 am   #22
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Default Re: European Black/Blue Mains Lead

Yes it was standard to have green earths and sleeving.
Red and black always had green earth wire, so did the 3 phase red, blue, & yellow with black neutral and green earth, though 3 phase flex is a bit less common.
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Old 7th Oct 2017, 11:07 am   #23
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Default Re: European Black/Blue Mains Lead

Quote:
Originally Posted by cmjones01 View Post
Yes, the assumption that live and neutral can reliably be distinguished, like in the UK, is very much the exception. In much of the rest of the world, it's just pot luck how the sockets are wired - even when they're 3-pin ones which can only fit one way round. This applies today as much as ever.
Split phase power is also much more common in Europe than the UK, where you only find it in the odd remote farm. Under split phase there is no neutral and both connectors are at 115V with regard to earth.
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Old 7th Oct 2017, 11:19 am   #24
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Default Re: European Black/Blue Mains Lead

Quote:
Originally Posted by Philips210 View Post

I've never seen a mains flex with Red, Black and Green/Yellow wires.
Going through (one of) Dad's boxes of "one day" junk the other day, I found a 3m length of same, unfortunately I stripped it for the cores just before I saw this post, otherwise I'd have posted a photo as proof. I've lots of current cable around, I don't like having non-compliant stuff....
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Old 7th Oct 2017, 12:46 pm   #25
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Default Re: European Black/Blue Mains Lead

Some old flexes had an earth with just bare copper wire in the outer coating.
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Old 9th Oct 2017, 10:33 am   #26
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Default Re: European Black/Blue Mains Lead

UK split phase supplies are usually at a much higher voltage than those overseas, and DO have a neutral.

230/240 volts between either live and the neutral, with 460/480 volts between the two live conductors.

Utilised when only a single phase HV supply is available. Fairly common in rural areas.
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Old 9th Oct 2017, 10:45 am   #27
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Default Re: European Black/Blue Mains Lead

I think the green/yellow earth conductor came about because people with colour blindness had difficulty distinguishing between red and green. The lighter colours plus the stripe made it easier and safer.
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Old 9th Oct 2017, 12:54 pm   #28
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Default Re: European Black/Blue Mains Lead

Parts of the Continent used to use three-phase supplies but arranged as 127V phase-to-neutral, giving 220V phase-to-phase. So neither pin of a 220V connection would be safe to touch.

I don't think the UK ever used 138V phase-to-neutral / 240V phase-to-phase, but I'm willing to be corrected .....
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Old 9th Oct 2017, 1:07 pm   #29
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Default Re: European Black/Blue Mains Lead

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Originally Posted by vidjoman View Post
I think the green/yellow earth conductor came about because people with colour blindness had difficulty distinguishing between red and green. The lighter colours plus the stripe made it easier and safer.
I believe that you are correct, persons with significantly defective colour vision should normally avoid working on the fixed electrical installation, but might well need to fit a plug.
Knowing that the stripped wire was the earth could be vital. Interchanging live and neutral seldom mattered much on a portable appliance, remembering that in many countries socket outlets were not polarised.
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Old 9th Oct 2017, 1:13 pm   #30
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Default Re: European Black/Blue Mains Lead

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Originally Posted by julie_m View Post
I don't think the UK ever used 138V phase-to-neutral / 240V phase-to-phase, but I'm willing to be corrected .....
138/240 was never widespread, but remembering the multitude of different systems used in parts of the UK, I bet someone, somewhere used it.

Some time ago, there was a discussion on these fora about the purpose of a 140 volt tapping on the mains transformer of some vintage appliance, suggesting that somewhere used 138/240.
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Old 9th Oct 2017, 5:06 pm   #31
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Default Re: European Black/Blue Mains Lead

We've just had a H&S bulletin at work detailing a three phase supply fed via a single phase isolator (at another company). Red and blue phases through the switch. Yellow phase sleeved in yellow/green and connected straight through via the earthing terminal
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Old 9th Oct 2017, 7:59 pm   #32
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Default Re: European Black/Blue Mains Lead

Quote:
So neither pin of a 220V connection would be safe to touch.
None of the power supplying conductors are intended to be "safe to touch" that is why we have an earth connexion or double insulation. IMHO isolation is better than an earth because to get a shock via two bits of kit you have to have two faults, with an earth only one fault is needed.
 
Old 9th Oct 2017, 8:22 pm   #33
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Default Re: European Black/Blue Mains Lead

My late brother-in-law's house in France was originally wired with a three-ohase supply in which green insulated cable was used for the three individual phase conductor connections from the main company fuse to the local distribution boards. There did not seem to be any standardisation in the wiring of the final circuits, which seemed to have all the colours of the rainbow. French installation practice for domestic wiring seems to be to use flexible corrugated plastic conduit with individual wires, and the Bricomarches sell coils of flexible plastic conduit pre-loaded with the appropriate sizes and numbers of conductors.
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Old 9th Oct 2017, 8:30 pm   #34
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Default Re: European Black/Blue Mains Lead

Quote:
Originally Posted by merlinmaxwell View Post
IMHO isolation is better than an earth because to get a shock via two bits of kit you have to have two faults, with an earth only one fault is needed.
Isolation is great, but then it's possible to have one fault in the system (one live conductor getting earthed by accident) which goes undetected until a second fault occurs and you have a completely unprotected shock hazard. That's why isolated systems powering any more than one appliance are supposed to have insulation monitoring devices so that first fault can be detected and dealt with. I believe some ships are wired this way to give their wiring a measure of fault-tolerance.

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Old 9th Oct 2017, 8:41 pm   #35
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Default Re: European Black/Blue Mains Lead

Quote:
I've never seen a mains flex with Red, Black and Green/Yellow wires.
See below! Very much a transitional product.

Quote:
green insulated cable was used for the three individual phase conductor connections
Was standard in Holland with a red neutral. Very counter-intuitive when brought up on UK colours!
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Old 9th Oct 2017, 9:24 pm   #36
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Default Re: European Black/Blue Mains Lead

Quote:
Originally Posted by merlinmaxwell View Post
None of the power supplying conductors are intended to be "safe to touch" that is why we have an earth connexion or double insulation.
In the UK, the Earth and Neutral are joined at the substation and again at every building; so that is good multiple redundancy.

Now, obviously a break in the wiring inside the customer's premises can still cause the neutral wire to become live. So I agree the Neutral is not necessarily safe to touch, especially under fault conditions (including cross-wiring from one circuit to another; fine with wire fuses, but replace the consumer unit with one using double-pole MCBs and now you have a situation where the neutral return wire can become live .....) (But that's why you use a neon screwdriver on it, and also on a known live terminal before and after, so you can be sure the neon did not light because the wire isn't live and not because it's faulty, and then approach it cautiously with the outside of your hand so if it is live, your muscles will tense and pull you away. Or whatever modern trendy digital instrument they're using nowadays; neons are so last century .....)
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Old 9th Oct 2017, 9:36 pm   #37
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Default Re: European Black/Blue Mains Lead

Looking back at the photos I took, Red was indeed used for the incoming neutral as per Dutch practice, although for most of the ongoing wiring, White was used.. Blue, Green, and Red were all used for various onward Phase conductors. At least the original installers had written on the conduits where they led to. The house was built in the mid-1960's and subsequently converted to single phase without amending the original wiring, leaving two 3-phase power sockets in situ with all three poles live and connected to the same phase. The wiring was actually installed to a high standard, and in accordance with the then-current French practice, plug-in non-rewirable ceramic cartridge fuses were proved at every light switch and every socket outlet. You had to unscrew the socket or switch to gain access.

A good reason for the use of striped insulation for the earth to avoid ambiguity with legacy continental wiring.
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Last edited by emeritus; 9th Oct 2017 at 9:42 pm.
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Old 10th Oct 2017, 12:04 am   #38
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Default Re: European Black/Blue Mains Lead

Quote:
Earth and Neutral are joined at the substation and again at every building
Only if the supply is visibly TN-C-S (i.e. the Main Earthing Terminal is connected to the neutral bar in the service terminal equipment) and/or there is a sign indicating the presence of PME, can you assume this. There are areas with mainly TN-S services, eg with legacy distribution and service cables, where the earth is taken from the sheath independently of the neutral, the two being common only at the substation. Then there are the many buildings where the supplier makes no connection to the Main Earthing Terminal and that is earthed solely to a stand-alone local rod. In some situations, such as building sites, caravans etc where it is expressly prohibited for the CNE (combined Neutral / Earth) conductor to be connected to the MET. Even if the supplier provides a PME service, one must again configure as TT and earth to the rod only.

Quote:
Or whatever modern trendy digital instrument they're using nowadays; neons are so last century
Only a GS38 Approved Voltage Indicator is acceptable. Testing with a neon screwdriver (or even a multimeter) in industry will likely land you in hot water.
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Old 10th Oct 2017, 9:09 pm   #39
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Default Re: European Black/Blue Mains Lead

~2.5mm Blue/Black and plain copper earth?
Go to Norway, Clas Ohlson. It's what they have.

In any house of some age, blue and black might be swapped at any socket, the earth wire might be connected through or not. Fun.

Start over from the distribution board which was 115/115 + Earth I found out. Fuse in each side. Take out 2 or regret it....

And I almost forgot - later versions have aluminium foil overwrap. That means when you strip it you bleed from a thousand cuts. It's thin but very sharp.
Assume it's in contact with earth, good for the hum on pantry transmitters perhaps?

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Old 10th Oct 2017, 9:50 pm   #40
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Default Re: European Black/Blue Mains Lead

Norway still has some systems of 2wires at 127 volts giving 220 across the 2 with no neutral I think that now they have RCDs they cant wire 127 volt appliance between the un metered phase and a local earth rod which once was common practice.
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