Electrical wiring

Zu Teil 9: Material properties

This is something Jack wants Lucy to really understand and he thinks that some explanations on this subject are very useful for her to make sure that she keeps her hands off wires.  

Lucy: So, what is it, Uncle Jack, that you want to tell me today?

Jack: What I want to tell you today is very important for your safety. We’ve talked about electricity before but there’s more to it.

Lucy: I’m not sure I will ever understand the difference between watts, volts, and amperes etc. Physics wasn’t my favourite subject in school.

Jack: To make it easier for you to understand, you can think of electricity in terms of water being pumped through pipes. Voltage is the pressure that is produced by the pump, it’s measured in volts. Current, which is measured in amps, is the flow rate, i.e. how fast the water flows through the pipes and ohm is the resistance that acts on the water. The more restrictions, the higher the resistance. Watts would be the power (volts x amps) the water could provide. Think back to the old days when water was used to power mills. So, electricity is the flow, like water, of electrons through a conductor like a wire. The rate at which electricity flows is measured as an electric current. The electric current is measured in amps. But what makes the current flow? In our water comparison we could say a battery would be the pump that makes the water flow which creates pressure in the pipe. The pressure is the voltage. And as we said before the watts are the power the water could provide. Watt is a measure of how much power is released each second.

Lucy: Oh, that was a good example. If you had been my physics teacher, my marks definitely would have been better.

Jack: Nice idea, Lucy, but I’m quite happy with my job. But now that you’ve understood all this, let me tell you some of the basics of electrical wiring. An electrical wire is made up of a material that is able to conduct electricity, known simply as a conductor. So electrical conductors are materials that allow electricity to flow through them easily. Most metals are good conductors. In home wiring systems the conductor can either be one thick strand of aluminium or copper, or it can be multiple strands of conducting material grouped together to form one single wire. Electrical insulators on the other hand are materials that do not allow electricity to flow through them. Most plastic and ceramic materials are insulators.

Lucy: What about water?

Jack: Well, good question, my dear. Some materials are insulators in pure form, but will conduct if there are small quantities of another element or if they contain impurities. Pure water is an insulator, but dirty water conducts weakly and salt water conducts well.

Lucy: So, what is the best electrical conductor?

Jack: The best electrical conductor when you have ordinary temperature and pressure, is the metallic element silver. It’s not always ideal as a material, though, because of its cost and because it tarnishes. The oxide layer known as tarnish is not conductive. Similarly, rust, verdigris, and other oxide layers reduce conductivity.

Lucy: And what other electrical conductors can you use?

Jack: You can also use aluminium foil, for example, or copper, graphite, steel, just to mention a few. But despite competition from other materials, copper remains the preferred electrical conductor in nearly all categories of electrical wiring because of its many good material properties.

Lucy: What about heat?

Jack: Materials that conduct heat are thermal conductors and there are also acoustical conductors which transfer sound. There are corresponding insulators for each type of conductor. Many materials are electrical and thermal conductors or insulators at the same time. However, there are exceptions. Don’t assume just because something conducts or insulates ​ one form of energy that it behaves the same for other forms! Metals typically conduct both heat and electricity. While carbon conducts ​ electricity as graphite, it insulates as diamond. So, the form or allotrope of a material can be important. Gold and silver are thermal conductors. Polystyrene foam, water, mineral wool and plastic, on the other hand, are thermal insulators.

Lucy: And what exactly do the different colours of the wires mean?

Jack: To prevent wires from shocking, they are insulated in a non-conductive plastic coating. The United Kingdom introduced a new wiring colour system in 2006 so that we would be in line with the rest of mainland Europe. In this way all countries of the European Union have the same wiring colour system now which is a big advantage because as an EU citizen you’re currently allowed to work in any other EU country. So, you see, Lucy, you can apply the skills you’re learning with me here also in Germany when you go back.

Lucy: Of course, Uncle Jack, provided that you have told me all about it by then.

Jack: Oh yes, sorry, I sometimes get carried away. An appropriately wired home in the UK has three colours for three different functions: brown for live, blue for neutral and yellow and green for earth. The only wires that are truly safe to touch are the earth wires coated in yellow and green plastic. They do not form part of electric circuits. They don’t carry electricity, but are instead used as fail-safe if something goes wrong with a hot wire.

Lucy: How have wiring colours changed in the UK?

Jack: The former neutral black has been replaced by blue, the red has been replaced by brown and the earth is still identified by green and yellow.

Lucy: What about the older houses that have wiring from before 2006?

Jack: Well, as the owner of such a house you should consider having them replaced by a professional electrician. The old colours are outdated and now illegal for new installations in the UK. But, of course, you still have to know the old system. There’s a simple rhyme to remember:

• Touch red and you’ll be dead.
• Touch brown and you’ll go down.

Lucy: I hope I can remember it in this way. Does this mean that all other cables have completely different colours to avoid confusion?

Jack: Unfortunately, it’s not as easy as that. TV aerial cables do not carry any voltage but many are brown in colour – the same colour as the new »live« wiring. Many satellite and cable TV customers will have a black cable going into the back of their TVs, the same colour as the old neutral wire.

Lucy: What are the signs that old wiring should be replaced?

Jack: If your electrical appliances trip regularly, or you find lights flickering and dimming unprompted, you may find that your wiring is getting unreliable. More worrying is a burning smell, any sign of charred switches or receiving mild shocks when touching a light switch. In any of these instances, call for the assistance of an electrician immediately. Always be on the safe side with electricity and if you’re in doubt, call Jack Wire.

Lucy: End of advertising for today, Uncle Jack. We’re done.

Linking words (Verbindungswörter)

Linking words show how one piece of a conversation is connected to another piece of a conversation.

Addition (Zusatz)

moreover; in addition; additionally; further; further to this; also; besides; (außerdem; des Weiteren; ebenso; außer)

• Additionally, there are many more materials with good conductivity.
• Besides plastic, you could also use rubber.

Example (Beispiel)

for example; for instance; such as (zum Beispiel; wie zum Beispiel)

• Silver for example is the best conductor.
• Materials such as silver and gold are too expensive.

  Contrast (Gegensatz)

between two separate things, people, ideas, etc. However; in contrast; yet; despite the fact that; in spite of the fact that; nevertheless; nonetheless; on the one hand ….. on the other hand; but; although; even though; while
(jedoch; im Gegensatz dazu; trotz der Tatsache, dass …; trotzdem; auf der einen Seite ... auf der anderen Seite; aber; obwohl; während)

• Even though silver is the best conductor, it is too expensive.
• However, there are exceptions.

Cause and effect (Ursache und Wirkung)

As a result of; because of; so; thus; due to (this fact); consequently; for this reason
(Daher; wegen; so; auf diese Weise; aufgrund (dieser Tatsache); folglich; aus diesem Grund)

• As a result of the new legal regulations in the UK, all old wiring systems should be replaced.
• Thus, electricians can earn a lot of money.

Expressing a condition (Bedingung)

If; in the event of; as long as...; provided that...; assuming that...; given that....
(Falls; wenn; solange…; vorausgesetzt, dass…; angenommen, dass…)

• If a house is older than 20 years, the wires will still have the old colours.
• You’re always on the safe side, provided a certified electrician has installed the wiring.

Conclusion (Schlussfolgerung, Abschluss)

As a result; consequently; in conclusion; to sum up; to summarize
(Folglich; infolgedessen; abschließend; zusammenfassend)

• As a result of the new colouring system for wires, many people find it confusing to remember the colours correctly.
• In conclusion you can say that it´s a good thing to have a uniform colouring system in the entire EU.

  Such linking words are either placed at the beginning of a sentence or to connect two sentences.  

Conditionals/if-clauses (Bedingungssätze)

Meaning and use

Conditional sentences express a connection between two actions or states. One thing happens because of another.

Zero conditionals

We use them to talk about general truths and scientific facts. One thing happens and because of this something else happens.

If and when have the same meaning in zero conditionals.

 If-clause: Present Simple, main clause: Present Simple

If you heat water enough, it boils.
Wenn man Wasser ausreichend erhitzt, kocht es.

Water freezes outside when/if it is cold enough.
Wasser gefriert draußen, wenn es kalt genug ist.  

First conditionals/If-clauses type I

Used when we want to talk about something that is likely to happen in the future under certain circumstances, the condition.

If-clause: Present Simple, main clause: Future (will+infinitive)

If you replace the old wiring, you will be on the safe side.
Wenn man alte Leitungen ersetzt, ist man auf der sicheren Seite.  

I will use my umbrella if it rains.
Wenn/falls es regnet, nehme ich meinen Schirm.  

Second conditionals/If-clauses type II

Refer to an imagined present result of an unlikely or impossible present condition.

If-clause: Past Tense, main clause: Conditional I (would + infinitive)

If you replaced the old wiring, you would be on the safe side.
Wenn du (man) die alten Leitungen ersetzen würdest (würde), wärst du (wäre man) auf der sicheren Seite.

I’d travel around the world if I had a lot of money. (I don’t have the money)
Ich würde um die Welt reisen, wenn ich viel Geld hätte.

If I were you, I would (I’d) go home now.
Wenn ich du wäre, würde ich jetzt nach Hause gehen.
Exception: the verb »to be« takes »were« in 1^st and 2^nd person instead of »was« in 1^st person.

Third conditionals/If-clauses type III

Refer to an imagined past result of something that didn’t happen in the past.

If-clause: Past Perfect (had+3^rd verb form/past participle), main clause: Conditional II (would+have+3^rd verb form/past participle)

If you had replaced the old wiring, you would have been on the safe side.
Wenn du die alten Leitungen ersetzt hättest, wärst du auf der sicheren Seite gewesen.

You would have met Jane if you had come earlier.
Du hättest Jane getroffen, wenn du früher gekommen wärst.

Form

Conditional sentences usually have two parts, the if clause/conditional clause) and the result clause/ main clause.

The clauses can come in any order. The sequence of tenses (Zeitenfolgen) in the two parts of the sentence may not be changed! If the if clause is first, the two clauses are separated by a comma.

There is never a comma before »if«!

Never use »will« or »would« in the if-clause part of the sentence!