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Hello everyone!
I have just entered my 4th year of Appliance Engineering. I feel a bit anxious as there are still some things that are not clear in my mind that I really think should be cemented into my brain by now this far into the apprenticeship. Mainly about how electricity works, especially in appliances and circuitry. I am more looking for clarification than actual answers.
You might be wondering why I don’t just ask my boss. The quicker answer that I can give is that I am afraid to. If I may, would it be possible to post some questions here that I am struggling with and the experts can answer in there own time?
Any help you could give me would be gladly appreciated.
Re: Questions from a 4th year Apprentice
i would post them and see what happens
a point to note though is you are posting on a public forum where we have to be guarded about what we say
why dont you apply for trade membership, I am sure your boss wont say no to that and will help with the references reqd. After that you will have access to a wealth of knowledge
Dave
Re: Questions from a 4th year Apprentice
Newbiegoeasy wrote:Hello everyone!
I have just entered my 4th year of Appliance Engineering.
May we ask what your current job entails exactly? Appliance engineering is a very generalised term after all.
In answer to your question, there is a wealth of reference books you can take out of your local library covering every single aspect you seek. I suggest you take advantage of this for free, you can borrow the books for up to 5 months (you will need to renew every month though to retain them). Basic electrical and electronic theory covering all sorts of applications including domestic appliances.
Re: Questions from a 4th year Apprentice
Thanks very much for your responses guys.
I am sure your boss wont say no to that
Haha unfortunately no, Dave. I can imagine my bosses reaction to that.
May we ask what your current job entails exactly?
We repair domestic appliances i.e. washing machines, ovens, dishwashers etc. There are a lot of good looking books out there Martin – to the point I’m not sure which to pick. As i should be learning enough from my teacher, i thought it might be best just to ask a few basic questions on a likeminded forum rather than diving into more books (I have read a lot of Haynes manuals for various appliances).
I’ll post here and see what happens as Dave advised.
All i basically want to know is how the neutral wires works exactly in appliance circuitry.For example, before i started my apprenticeship, i always thought that on any and every circuit the live wire has current going into the load and the purpose of the nuetral wire was to curry current away and back to source. So without a neutral wire a closed circuit was not possible and a heater element, for example, could not operate.
That’s how i thought it worked. But when i relayed this to my boss i was made to feel very stupid. I was told that both a live wire and a neutral wire will carry current into a component. I read up on it but could not find anything anywhere which confirmed exactly what my boss said. Everything explained neutral the same as the example i gave above.
It actually was quite a while later before in realised that my idea of how nuetral worked was relevant to DC electricity. How my boss explained the way neutral worked in appliances was due it being AC. Is this correct? (I’m very serious when i say this was never explained to me).
So, as i understand it – both the live and neutral wires carry current into the component (heater element). As it is AC the current is oscillating back and forth slightly at a really fast rate. This is how current flows in an AC circuit and how the appliance is powered. The live wire carries the voltage whereas the neutral carries very little.
Is this correct?
Re: Questions from a 4th year Apprentice
Newbiegoeasy wrote:So, as i understand it – both the live and neutral wires carry current into the component (heater element). As it is AC the current is oscillating back and forth slightly at a really fast rate. This is how current flows in an AC circuit and how the appliance is powered. The live wire carries the voltage whereas the neutral carries very little.
Is this correct?
In both AC and DC circuits the wires transmit the current created by the load (the load in this example being a heating element). The live wire is ‘the supply feed’ the neutral ‘the return’.
I suspect your “boss” doesn’t truly understand electric circuits hence why you’re searching for answers elsewhere. I once had a boss like that and I was asking questions on how a refridgeration circuit worked. I realised he had no clue and I too asked others for answers and subsequently cooled his overblown ego.
So yes my friend, ask away.
Re: Questions from a 4th year Apprentice
If your Boss bit your head off through lack of knowledge then I have little respect for him. there must have been many times when he was learning that he got the wrong idea
To understand better you need to know how the supply comes into a house
the electric supply is carried round the country at very high voltages to reduce losses. but in the end it is tranformed down to 230V. The neutral wires is then bonded to an earth plate in the substation. This means that the neutral wires voltage is at or just above earth potential. So you could touch the neutral and not get a shock
all that asside no circuit will work without a current flow, and current in an AC circuit changes direction, so both wires carry the current to the load but 1 wires voltage is almost at earth potentialin fault conditions its the voltages you measure that give the game away. take a simple vacuum cleaner where the wire to the appliance has broken. if you measure no voltages on the terminal block then the live circuit has broken but if you measure all lives then the neutral has broken
Dave
Re: Questions from a 4th year Apprentice
Thanks very much for your help guys!!! It means a lot. Really.
My boss means well there is just little room for patience.
In both AC and DC circuits the wires transmit the current created by the load (the load in this example being a heating element). The live wire is ‘the supply feed’ the neutral ‘the return’.
This was what i originally assumed. But I’m not sure i fully understand this in regards to AC, Martin. If the current is constantly changing direction then how can it go into the load via the live wire (supply) and then out via the neutral (return)?
Or is it as Dave says where
current in an AC circuit changes direction, so both wires carry the current to the load
?
This makes more sense to me as it shows that both wires carry the current to the load although the voltage is in the live as the neutral voltage is relevant to ground.
Make sense?
Re: Questions from a 4th year Apprentice
its not easy but some of us have done a lot of electrical theory during our apprenticeships.
in some ways all you need to understand is how the circuit functions. all electrical wiring goes in circles, without 2 wires coming to and from the generating source nothing would work. forget about in and out its not relevant in an AC circuit.
if i am testing a valve to see if its energized first i will check for voltage across the valve and if i don’t get anything i will check again with 1 lead on the earth so i know whether its live or neutral missingDave
Re: Questions from a 4th year Apprentice
Also the convention in DC theory that it flow from +ve to -ve is also flawed after they discovered electrons where negatively charged and flowed the other way
http://www.mi.mun.ca/users/cchaulk/eltk … e/ivse.htm
Dave
Re: Questions from a 4th year Apprentice
Sounds like your boss is stuck in the dark ages, the whole point is to ask questions when your not 100{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} certain on something
Hopefully the answers on here will help. Good luckRe: Questions from a 4th year Apprentice
Hi guys,
I have been away the past couple of weeks so sorry for the lack of response.
So, just to summarise; it seems that my original assumptions were correct? The reason online tutorials weren’t telling me about neutral wires carrying current into a load (as my boss had explained) is because they were explaining the basic function of neutral in a circuit rather than the details of neutral in an AC circuit specifically? Is that correct?
Dave are you referring to a continuity test? Also, i had no idea about the discovery that electrons flow the other way. That is very interesting!
Re: Questions from a 4th year Apprentice
continuity test will tell you if a component is open circuit but will not tell you when its energised. the only way to do this is to look for voltages when the unit is powered up.
prob against all the health and safety regs these days but a darn site quickeras for the neural theory i would have to read the text to see where they are coming from
Dave
Re: Questions from a 4th year Apprentice
Ah right, using a multimeter? I need to get more proficient at that.
Not really, all basic explanations say that live goes in and neutral goes out. I just want ti know what my boss means by neutral carrying current in (to a load).
Re: Questions from a 4th year Apprentice
is a bit of a non argument. both wires carry the current that allows the load to do its work. so both wires carry load current. the only difference it you cant get a shock off a neutral as its bonded to earth
Dave
Re: Questions from a 4th year Apprentice
Newbiegoeasy wrote: I just want ti know what my boss means by neutral carrying current in (to a load).
This is really good news as it appears that last time you were on here communication between yourself and your boss were somewhat strained. Now he’s talking it’s a good time to ask him for clarification over his comment. Like electrofix I too am at a loss as to what he meant by that. 🙁
4 years into the job and only now are you getting help with very basic electrical. 🙁
You referred to a multimeter in your last post. Have you also been given access to using an insulation tester?
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