Curious on why..

[Lister1987]

Why do we have Ze, Zs , L1, L2 etc as names for tests instead of just straightforward what is being measured L-E etc and why Line and Live are used (correct me if wrong) for Brown/Black?

No doubt I'll find out the answers when I start in September, just found it curious....no doubt I'll have more stupid curiosities as I learn

 

[Deleted member 26818]

Z is a symbol used for Impedance.
Ze denotes the Impedance external to the installation.
Zs denotes the impedance of the complete system up to the point of measurement.

Not seen a test called L1, L2?

We don’t describe a test as L-E, because there are various tests conducted between L and E, and we need to identify which test result is being recorded.

Ze is the test to measure the impedance of the external L and E.
Zs is the test to measure the impedance of the complete run of L and E.
R1 + R2 is the test to measure the combined resistance of L and E.
R2 just the resistance of the E.
Then we have the insulation resistance test which tests the insulation resistance between L and E and other conductors.

We don’t describe a test as being between Brown/Black, because we might not have brown and black conductors.

Not sure about Line and Live being used for Brown and Black.
Bothe Brown and Black (along with Grey and Blue) are colours used to identify Live conductors.

A Live conductor is any which caries dangerous current/voltage.

I hope this helps.

 

[Lister1987]

Z is a symbol used for Impedance.
Ze denotes the Impedance external to the installation.
Zs denotes the impedance of the complete system up to the point of measurement.

Not seen a test called L1, L2?

We don’t describe a test as L-E, because there are various tests conducted between L and E, and we need to identify which test result is being recorded.

Ze is the test to measure the impedance of the external L and E.
Zs is the test to measure the impedance of the complete run of L and E.
R1 + R2 is the test to measure the combined resistance of L and E.
R2 just the resistance of the E.
Then we have the insulation resistance test which tests the insulation resistance between L and E and other conductors.

We don’t describe a test as being between Brown/Black, because we might not have brown and black conductors.

Not sure about Line and Live being used for Brown and Black.
Bothe Brown and Black (along with Grey and Blue) are colours used to identify Live conductors.

A Live conductor is any which caries dangerous current/voltage.

I hope this helps.

Certainly a start SpinLondon, thanks; and you're right R1 R2....head just went PlayStation on me.

Just wondered why Ze/Zs etc are used instead of something more straightforward like EI, EC, ER; earth impedance, earth circuit, Earth resistance or similar.

As for Live/Line, it could just be me. Maybe Line is used in place of Live so as not to confuse states (of whichever line/cable in question? I mean a live live, dead live, dead line etc

 

[Deleted member 26818]

Ze and Zs tests don’t just measure the impedance of the earth, they also measure the impedance of the Line.

Some test sheets use Live/Live because the test would be between Line and Neutral, or with 3 phase between each of the Line conductors.
This usually denotes the IR test, so both conductors would be dead.

 

[Lucien Nunes]

Many of these symbols aren't just abbreviations for the specific things you are testing or measuring, but references to fundamental scientific and engineering quantities and units. There are hundreds of them, and they have to be consistent across all branches of science and engineering, from astronomy to chemistry to wiring a plug. Greek letters, capital and lower case letters and various symbols all have their specific meanings that every engineer in the world will recognise, even if they don't use the words 'earth' or 'voltage' etc. in their language.

Z might look strange at first as a symbol for impedance, but having worked with it for decades, and its constituents R (resistance) and X (reactance) and their inverses Y (admittance), G (conductance) and B (susceptance), to me it is the very soul of impedance and the two are inseparable.

Re. Line and Live - for many decades the term 'live' was used for the 'brown' wire, which along with the neutral made up the circuit conductors. To avoid the specific situation that you describe, confusing the name of a conductor with what danger it poses, the definitions were changed in the 15th edition of 1981. The brown wire was renamed the 'phase', which together with the neutral made up the 'live' conductors. But 'phase' added a new ambiguity, so 17th edition of 2008 it was changed again so that the brown wire is now officially the 'line', actually an older and well established term that had been used with this meaning a century ago.

Non-electricians are unaware of this, so the letter L on a plug terminal is still read as 'live' by most of the population.

 

[Lister1987]

Many of these symbols aren't just abbreviations for the specific things you are testing or measuring, but references to fundamental scientific and engineering quantities and units. There are hundreds of them, and they have to be consistent across all branches of science and engineering, from astronomy to chemistry to wiring a plug. Greek letters, capital and lower case letters and various symbols all have their specific meanings that every engineer in the world will recognise, even if they don't use the words 'earth' or 'voltage' etc. in their language.

Z might look strange at first as a symbol for impedance, but having worked with it for decades, and its constituents R (resistance) and X (reactance) and their inverses Y (admittance), G (conductance) and B (susceptance), to me it is the very soul of impedance and the two are inseparable.

Re. Line and Live - for many decades the term 'live' was used for the 'brown' wire, which along with the neutral made up the circuit conductors. To avoid the specific situation that you describe, confusing the name of a conductor with what danger it poses, the definitions were changed in the 15th edition of 1981. The brown wire was renamed the 'phase', which together with the neutral made up the 'live' conductors. But 'phase' added a new ambiguity, so 17th edition of 2008 it was changed again so that the brown wire is now officially the 'line', actually an older and well established term that had been used with this meaning a century ago.

Non-electricians are unaware of this, so the letter L on a plug terminal is still read as 'live' by most of the population.

Cheers for the detailed explanation, make a bit more sense

 

[Silly Sausage]

Further reading ...

SI units

The International System of Units (SI units) is a globally agreed system of measurements that has been in place for more than two centuries.

www.npl.co.uk

 

[telectrix]

and the metric system was invented by head choppers in France c. 1800. based on an inaccurate measurement of the earth leading to the kilometre. but because even the most ignorant onion seller, garlic breath , froggie could multiply by 10, as long as he's not lost any fingers when being careless around the guillotine, it was adopted as a standard. gawd knows why since we had a perfectly good system of yards, chains, rods, furlongs and fathoms.

 

[Pete999]

and the metric system was invented by head choppers in France c. 1800. based on an inaccurate measurement of the earth leading to the kilometre. but because even the most ignorant onion seller, garlic breath , froggie could multiply by 10, as long as he's not lost any fingers when being careless around the guillotine, it was adopted as a standard. gawd knows why since we had a perfectly good system of yards, chains, rods, furlongs and fathoms.

Old is best Tel, a very good analogy of our friends across the Channel, the English Channel that is, not the French Channel, God forbid, just imagine the Garlic eaters would be charging us for using it, forgetting of course that we, along with the US and others saved their collective backsides just over 70 years ago. Sorry for rant.

 

[Bobster]

The metric system is far, far superior than imperial era weights/measures.

 

[Pete999]

The metric system is far, far superior than imperial era weights/measures.

Only because evert other country uses it Rob. LOL

 

[Bobster]

Only because evert other country uses it Rob. LOL

Spend most of my time in the states Pete, they're still in the past.

I know how to use imperial weights and measures, I learned it in school.

Start using imperial systems past basic measuring of a length of wood etc.. No thanks. Also process control and commonality between measurements. Far easier in base 10 (what we use to count).

 

[telectrix]

The metric system is far, far superior than imperial era weights/measures.

in what way...... confusing old ladies that want a pound of sausages and can't work out the cost per pound when it's quoted in kg. or is it petrol/diesel sold in litres so a 2p price increase looks minimal till to see that it's actually 9p (almost 2 shillings ) a gallon increase, or is it just that the modern generation can't multiply by 12 without using a calculator.

you could measure a yard with a decent stride, but those of us under 6ft.3" can't manage a metre. a football pitch is 1 acre. gawd knows how that translates into hectors. a horse is measured in hands. we all have hands, but who goes to buy a horse with a metric (ach.spit.) tape measure? and what about our cherished poets.... full fathom five your father lies... don't seem right as full 30 metres (ish) your father lies.
feet, yards, tons, weeks. that should be the new standard. i.e . a rewire uses 300 yards of T/E, weight of all supplied cable and equipment is 1/5 ton. job takes 2 weeks. what's hard about that?

 

[telectrix]

Only because evert other country uses it Rob. LOL

not every. U.S.A. have managed since 1776. even if their gallons are miscalculated. it's all a EU plot . good job we're leaving or we'd end up with the euro and driving on the wrong side of the road before me and pete enter sparky heaven.

 

[Pete999]

not every. U.S.A. have managed since 1776. even if their gallons are miscalculated. it's all a EU plot . good job we're leaving or we'd end up with the euro and driving on the wrong side of the road before me and pete enter sparky heaven.

Perish the thought!