Boys, boys boys...

There is a passage in the good book that states "dont cast your pearls before swine" If realy silly people want to do their own wiring and not pay any attention to rules etc (oh and I forgot OHM'S LAW that has never been repealed). Then so be it. As an ex electrician you will not get one squeek of advice from me on how to kill yourself!

BTW I had a good laugh at some of the foolish posts on this thread.. FFS Get an electrician!!!!!

JEEEEEZZZZZZZZ!!!!

rockylizard wrote:

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Gday...

Don't ya jest LOVE electrical threads?

Cheers - John

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YES

Especially when non qualified people give advise  on such a potentially dangerous subject.

Even worse ,when they insist they "know"

The sad thing is that many ELECTRICIANS are not aware of the Standard covering "Transportable Structures"AS/NZS 3001 & it's specific requirements that are in additional to the "Wiring Rules !!!

Also, while Im on the subject.

As a 6 year old kid my Dad (RIP) got me an electric train set for an Xmas pressy one year. Now the transformer had NO plug on the end for what ever reason (1956). I saw him poke 3 wires in the wall socket and switch it on and the train set worked.

I wanted to play with it early one morning. Poked in the 3 wires and blew the crap out of the transformer, blue the main fuse in our fuse box and more than likely the street feed fuse...

What you see is not what you get in electrical. PLEASE dont take the pee out of my old man. He stuffed up and could have killed me had I been hanging onto the metal case of the tranny.. EASY lesson here, dont get a 6 year old to wire your house or caravan.... BTW a 6 year old and a non licenced person have the same electrical skills set IMHO.

BTW Ive been an electrician most of my working life and IM STILL HERE!!!!!!

robol wrote:

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Dicko it would be better to use flex cable ( as noted on first page ) instead of the cable used in household fixed wiring. Flex will stand up much better to the constant vibration caused by travelling.
Cheers Rob.

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 In my post I stated I use "stranded" cable. Had a family room extension wired up by sparky to cater for 8 power points, the cable used was the one in the photo...does not look like an extension cable to me but permanent and is flexible to withstand some movement as in a caravan. I use similar type cable for my odd jobs.

rrobor wrote:

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Choice of cable is quite simple.

[1]If you have multi stranded cable with thin copper wire it will create more resistance. That creates heat

.[2]For internal wall wires the thicker the strands the better.

[3]As you increase frequency this becomes more important. At UHF frequencies the signal does not go down the inside of the wire it goes down the skin.

 

[4]So the reason you would not use extension wire inside a wall is the strands are thin to be flexible It is for temporary use.

 

 

 

 

Well part of above is partly correct

[1]Multi strand cable with thin copper with the same cross sectional area of copper has exactly the same Ohmic resistance,as a cable with fewer but thicker strands.,or even solid copper  That applies with DC & normal mains power frequencies.

[3]Skin effect only come into the picture at high frequencies ,[the higher the frequency the greater the effect,' so is of no concern for general power use

That Skin effect is put to good use with high to ultra high frequencies for purposes such as induction heating,  silver soldering assembled components that have fillings that could be damaged by normal methods ,case hardening,  localised stress relieving of welded joint in critical applications

 For those sorts of applications ,the frequency can range from 2000Hertz to many mega Hertz ,[often using water cooled inductor coils ]

Yes, I KNOW because I have worked with & repaired such units

[2]With 240V  @ supply frequencies :

[a]It makes NO difference as far as resistance is concerned if the cable is multi strand or solid !

Single strand copper cable is now rarely used ,even in domestic situation, the norm is now multi strand

[4]  NO ,being thin  has nothing to do with the reason ,why it should not be used for permanent /fixed wiring,so you can keep guessing 

 

Have You ever worked out why a say an 0 B&S cable [ 53mmx sectional area only has a continuous current rating of around 210A,yet a 20 B&S cable with around 1% of that cross sectional area has a current rating of  5A ??

Dick0 wrote:

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 In my post I stated I use "stranded" cable. Had a family room extension wired up by sparky to cater for 8 power points, the cable used was the one in the photo...does not look like an extension cable to me but permanent and is flexible to withstand some movement as in a caravan. I use similar type cable for my odd jobs.

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YES , THat is NOT extension lead or classed as flexible cable 

Standards approved multi core [twin & earth ,  plastic sheathed  [TPS] for permanent wiring ,under cover or protected from the elements. 

Shall NOT BE USED AS A FLEXIBLE CABLE!!

This is FLEXIBLE  CABLE "'Flex Cable 2C+E 2.5mm2 50/0.25mm PVC Flex 250/440v O/Duty Grey "

good old "O/Duty " {ordinary duty },not even heavy duty ,GREY flexible cable, for such as EXTENSION leads & leads on appliances /devices etc

rrobor wrote:

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1..  If you have multi stranded cable with thin copper wire it will create more resistance. That creates heat. For internal wall wires the thicker the strands the better.

2..  As you increase frequency this becomes more important. At UHF frequencies the signal does not go down the inside of the wire it goes down the skin. 

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 1..  The thin wires used in electric cords do have a higher resistance than the thicker house wiring wires, individually. However when you add the wires together to produce the same cross sectional area then the result is the same resistance in both cables. The same resistance will produce the same power loss for a given length of cable no matter how many wires go up to make the required cross section.

2..  Skin effect is only important in each wire in a cable if the wire is big enough for it to take effect. AT 60 Hz the skin depth is about 8.5 mm (200 mm2) so for any cable below 16 mm diameter we can discount skin effect at our mains frequency. If you don't insulate the strands of a multi stranded cable then the skin effect is taken over the whole diameter of the cable, that's why they developed Litz wire.

You should have quit some time ago whilst you were still ahead. You are becoming more stupid as you go along.

rrobor wrote:

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It is amazing how people attack what was meant to be a simple explanation of current flow in a conductor. Perhaps attack and try to kill is your best defense.
Electrons flowing through a conductor repulse other electrons. At DC or low frequency, electrons flow within the conductor and skin effect does not come into it. If you have 2 x 1mm conductors and a 2 mm solid conductor conducting current and you care to put an oscilloscope on both lines, you would find more white noise on the thinner wire. White noise is the impedance caused by electrons to other electrons flowing in the conductor. Try it gents. Rob.

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Ohh my God  & he talks about simple explanations!!

I guess you are "trying to explain  the electron theory of current flow

A typical example of a little knowledge but not much else!!

What an utter load of crap.

This forum is about Normal MAINS frequency  & DC ,of which you seem to know little!!

Very, very, few members have any interest in subjects dealing with high & ultra high frequencies.

Please tell us YOUR Qualifications ,

How did you earn the right to call yourself an Electronics" technician "?

Do you have any recognised certifIcates?

ps I spent a major part of my working life in the industrial electronics field .

Come on people,       I am sweating on Four Pages on this Post.  Better than watching Peyton Place   

Thanks everyone for your input on this but I think I'll close this thread now. Just a reminder to please keep posts friendly and respectful.  Although we welcome differing points of view, we do not allow personal attacks.