Are any of you blokes actually qualified to give Mark your advise? Curious?

I've changed paths myself Greeny, but the last time i checked, electricity hasn't changed for over 100 years. But the only person fully qualified to take the responsibility is the guy who puts his contractor's license number on the install.

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Greenroom said..
Are any of you blokes actually qualified to give Mark your advise? Curious?

I was always of the understanding that qualification disqualifies you from providing advice on SB.

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Greenroom said..
Are any of you blokes actually qualified to give Mark your advise? Curious?

I wouldn't get to excited about asking that question. If he really cared about the answer he would ask someone with credentials.

Someone just said :

"1mm FLEX is good for 10A."

Which is absolutely terrible advice. 1mm flex is good for 10A? At what distance? 1M? 100M? The answer obviously differs, depending on what you do. It's easy to dump on someone, but far easier to offer advice that makes sense in context.

My brother and brother in-law are both electricians. I would happily trust them to wire stuff up and stick to the regulations. Knowledge about electronics? Not a chance. Understanding of why there are different ratings? Maybe. Ohms law? I very much doubt they remember it as they would never need to use it.

Hey FN, when it comes to current carrying capacity, distance is irrelevant, distance is only a consideration for voltage drop and fault current loop impedance checks (to check your protection will work properly). Flex can carry more current because the insulation on flex has a greater ability to withstand temperature rise, but you've gotta consider the energy let through of your protective device as well (ie under a bolted fault, how much energy gets let through the protective device before it trips/ruptures and will that energy cause enough temperature rise to destroy the insulation on the cable and therefore the cable?) It's a magic roundabout of protective considerations ................ anyway, back to the accounting for me

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Paddles B'mere said..
Hey FN, when it comes to current carrying capacity, distance is irrelevant, distance is only a consideration for voltage drop and fault current loop impedance checks (to check your protection will work properly). Flex can carry more current because the insulation on flex has a greater ability to withstand temperature rise, but you've gotta consider the energy let through of your protective device as well (ie under a bolted fault, how much energy gets let through the protective device before it trips/ruptures and will that energy cause enough temperature rise to destroy the insulation on the cable and therefore the cable?) It's a magic roundabout of protective considerations ................ anyway, back to the accounting for me

Yes I understand that, but in the context of '1mm flex is good for 10amps', you obviously need to consider the voltage drop for the load that you are powering. You could pass 10amp across 0.1mm if you wanted, but it's clear that you would get a higher voltage drop unless you are using a superconductor.

In the real-world no one cares if 1mm can pass 10amps. They want to know if the lead can pass the required current with only a reasonable voltage drop.

Unless of course you are the marketing department of a place that makes extension leads, then you can call your 1.5mm extension lead 'heavy duty - 15 amps' without qualifying anything else.

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Paddles B'mere said..
Hey FN, when it comes to current carrying capacity, distance is irrelevant, distance is only a consideration for voltage drop and fault current loop impedance checks (to check your protection will work properly). Flex can carry more current because the insulation on flex has a greater ability to withstand temperature rise, but you've gotta consider the energy let through of your protective device as well (ie under a bolted fault, how much energy gets let through the protective device before it trips/ruptures and will that energy cause enough temperature rise to destroy the insulation on the cable and therefore the cable?) It's a magic roundabout of protective considerations ................ anyway, back to the accounting for me

Let me get this straight....you've gone from being in some kind of electrical trade...sparky, technician.....to becoming an accountant? If you'd said maths or TAFE teacher, fair enough....but....accounting!!!???

As bizarre as it sounds .................. yes Harrow .................. I worked as a technologist/engineer for 25 years and then my wife (the accountant) needed a hand to run our little fledgling seaside accounting practice. I mainly worked with bulk materials handling so when the bottom dropped out of the engineering boom here in QLD I didn't want to get put on another FIFO roster and be sent even further away from my family any more so I went back to school to be my wife's whipping boy. The pay is krap, but she lets me windsurf or go to the MX track for my mental health breaks

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Paddles B'mere said..
As bizarre as it sounds .................. yes Harrow .................. I worked as a technologist/engineer for 25 years and then my wife (the accountant) needed a hand to run our little fledgling seaside accounting practice. I mainly worked with bulk materials handling so when the bottom dropped out of the engineering boom here in QLD I didn't want to get put on another FIFO roster and be sent even further away from my family any more so I went back to school to be my wife's whipping boy. The pay is krap, but she lets me windsurf or go to the MX track for my mental health breaks

Fair enough, I worked for my wife for 6 months after putting my hand up for a VR 4 years ago and quite enjoyed it, although I bet it's not for everyone. There are some definite advantages when you sleep with the boss.

Yep, at P&C meetings it requires full disclosure that I'm sleeping with the auditor

FN oh my bloody hell are you serious?
Yes 1mm flex is good for 10A but you have got to be a dumb carnt to think you can run flex far enough to consider volt drop. Mamma fkn mia!

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Paddles B'mere said..
I worked as a technologist/engineer for 25 years...

So a glorified train driver! Engineers all think they are sparkies hahaha pull the other one

Seriously fellas. Why tell Mark things you believe are correct. Unless you are qualified then go for it! As far as I'm concerned the only person qualified to answer his questions is an A grade electrician or above.

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FormulaNova said..
My brother and brother in-law are both electricians. I would happily trust them to wire stuff up and stick to the regulations. Knowledge about electronics? Not a chance. Understanding of why there are different ratings? Maybe. Ohms law? I very much doubt they remember it as they would never need to use it.

Go and ask them and come back with the answer.

Yes Greeny, sparkies can be more difficult to manage than a room full of hairdressers at times ...... definitely the most high maintenance guys on site

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Greenroom said..

FormulaNova said..
My brother and brother in-law are both electricians. I would happily trust them to wire stuff up and stick to the regulations. Knowledge about electronics? Not a chance. Understanding of why there are different ratings? Maybe. Ohms law? I very much doubt they remember it as they would never need to use it.

Go and ask them and come back with the answer.

Nah, not even going to bother. It would just show the difference between someone that wires stuff up and someone that understands electronics.

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FormulaNova said..

Greenroom said..

FormulaNova said..
My brother and brother in-law are both electricians. I would happily trust them to wire stuff up and stick to the regulations. Knowledge about electronics? Not a chance. Understanding of why there are different ratings? Maybe. Ohms law? I very much doubt they remember it as they would never need to use it.

Go and ask them and come back with the answer.

Nah, not even going to bother. It would just show the difference between someone that wires stuff up and someone that understands electronics.

Hahaha electronics!

Bwahaha ................ that's my understanding of electronics too .................... why isn't the box black with no windows

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Greenroom said..
Seriously fellas. Why tell Mark things you believe are correct. Unless you are qualified then go for it! As far as I'm concerned the only person qualified to answer his questions is an A grade electrician or above.

Does AS3000 dictate how long an extension lead someone can use in their driveway to run a particular compressor?

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Greenroom said..

FormulaNova said..

Greenroom said..

FormulaNova said..
My brother and brother in-law are both electricians. I would happily trust them to wire stuff up and stick to the regulations. Knowledge about electronics? Not a chance. Understanding of why there are different ratings? Maybe. Ohms law? I very much doubt they remember it as they would never need to use it.

Go and ask them and come back with the answer.

Nah, not even going to bother. It would just show the difference between someone that wires stuff up and someone that understands electronics.

Hahaha electronics!

When I was doing my associate diploma in electrical engineering at TAFE, one of the courses included a hands-on electrical wiring subject.

We went into this classroom, the teacher gave us instructions to wire up the boards according to the diagram on the blackboard, and then he disappeared.

We all wired it up, and then stood around talking for an hour before he came back. He looked at all the boards, looked puzzled, and then told us something like 'my last class would still be going'.

I think that tells me the difference between someone that wires stuff up and someone that understands why.

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FormulaNova said..
.... Just like all these people that attach a plug onto both ends of a lead to power a caravan from an internal socket.

I meant to ask, when do you see people doing that? Why aren't they happy with using the external socket on the caravan?

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FormulaNova said..

Greenroom said..

FormulaNova said..

Greenroom said..

FormulaNova said..
My brother and brother in-law are both electricians. I would happily trust them to wire stuff up and stick to the regulations. Knowledge about electronics? Not a chance. Understanding of why there are different ratings? Maybe. Ohms law? I very much doubt they remember it as they would never need to use it.

Go and ask them and come back with the answer.

Nah, not even going to bother. It would just show the difference between someone that wires stuff up and someone that understands electronics.

Hahaha electronics!

When I was doing my associate diploma in electrical engineering at TAFE, one of the courses included a hands-on electrical wiring subject.

We went into this classroom, the teacher gave us instructions to wire up the boards according to the diagram on the blackboard, and then he disappeared.

We all wired it up, and then stood around talking for an hour before he came back. He looked at all the boards, looked puzzled, and then told us something like 'my last class would still be going'.

I think that tells me the difference between someone that wires stuff up and someone that understands why.

Ah so you wired up a light switch and a power point yew!

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Harrow said..

FormulaNova said..
.... Just like all these people that attach a plug onto both ends of a lead to power a caravan from an internal socket.

I meant to ask, when do you see people doing that? Why aren't they happy with using the external socket on the caravan?

I think some people would be worried about the weather proofing of the external plug. That's the only thing I can think of.

I remember as a kid helping to clean out a caravan that an auntie had just bought, and there was a plug lying in a cupboard, which was the end of the a cable where the plug was already plugged into one of the caravan points. A death-trap but the person that did it probably thought 'yeah, its okay, I know its there', and ignoring the now live external plug.

Hopefully with RCDs now everywhere that is reduces the risk of this, and hopefully people now do the right thing.

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FormulaNova said..

I think some people would be worried about the weather proofing of the external plug. That's the only thing I can think of.

They balked at the price of 15 amp stuff vs. 10 amp stuff. You'd buy 20 or 30 ten amp plugs for the price of a caravan inlet and a 15 amp socket. Hard to find a 10 amp caravan inlet.

Is an extension lead with a 10 amp plug on one end and a 15 amp socket on the other legal? i.e..for someone wanting to power up a caravan when they pull up at a friends place with 10 amp outlets?

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Ian K said..

FormulaNova said..

I think some people would be worried about the weather proofing of the external plug. That's the only thing I can think of.

They balked at the price of 15 amp stuff vs. 10 amp stuff. You'd buy 20 or 30 ten amp plugs for the price of a caravan inlet and a 15 amp socket. Hard to find a 10 amp caravan inlet.

Is an extension lead with a 10 amp plug on one end and a 15 amp socket on the other legal? i.e..for someone wanting to power up a caravan when they pull up at a friends place with 10 amp outlets?

I think they may be legal, may even be available at a retail level. I have a vague memory of seeing one at a hire firm that had been tested and tagged..

One thing is for sure, they are pretty common.

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kk said..

Ian K said..

FormulaNova said..

I think some people would be worried about the weather proofing of the external plug. That's the only thing I can think of.

They balked at the price of 15 amp stuff vs. 10 amp stuff. You'd buy 20 or 30 ten amp plugs for the price of a caravan inlet and a 15 amp socket. Hard to find a 10 amp caravan inlet.

Is an extension lead with a 10 amp plug on one end and a 15 amp socket on the other legal? i.e..for someone wanting to power up a caravan when they pull up at a friends place with 10 amp outlets?

I think they may be legal, may even be available at a retail level. I have a vague memory of seeing one at a hire firm that had been tested and tagged..

One thing is for sure, they are pretty common.

No they aren't legal, but a supplier has come up with a solution which has a 10am plug on one end and a 15amp socket on the other, with a RCD/MCBO inbetween. The idea is that it cannot operate at more than 10amps, hence not able to draw too much through the 10a GPO.

I think Supercheap even sell them now, and I have seen them advertised somewhere else. I suggested to my father that he buy one but he thought they were too expensive, but they aren't that bad at all as they give you a legal solution.

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FormulaNova said..

Greenroom said..

Ah so you wired up a light switch and a power point yew!

That's not what you should be applauding, you should be worried about the apprentices doing the same subject that couldn't.

Just like any trades there are people that know their stuff and people that just do whatever they have done before. If you can tell me '1mm is fine for 10amps' but not tell me why, then I guess I know which bucket you are in.

I do this for a living. 5th generation and my son is 6th. Calculating volt drop, cable selection, conduit sizes, maximum demand, installing it all while being compliant, testing and recording it on thousands of dollars worth of meters and fit off down to the very last switch and gpo.
Rather not cast pearls before swine

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Greenroom said..
FN oh my bloody hell are you serious?
Yes 1mm flex is good for 10A but you have got to be a dumb carnt to think you can run flex far enough to consider volt drop. Mamma fkn mia!

This might be the quote behind Formula's erroneous assumption. You seem to be saying voltage drop is negligible over any practical distance you might run an extension lead. In which case wouldn't energy dissipated in the cable also be negligible? If so why don't they use a 0.5 mm copper core to do the same job? ( Grading conductors in mm infers we are referring to the diameter of the conductor, some specs seem to infer that it's the cross sectional area - what is it ? )

Always cross sectional area in Australian Standards Ian.

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Ian K said..

Greenroom said..
FN oh my bloody hell are you serious?
Yes 1mm flex is good for 10A but you have got to be a dumb carnt to think you can run flex far enough to consider volt drop. Mamma fkn mia!

This might be the quote behind Formula's erroneous assumption. You seem to be saying voltage drop is negligible over any practical distance you might run an extension lead. In which case wouldn't energy dissipated in the cable also be negligible? If so why don't they use a 0.5 mm copper core to do the same job? ( Grading conductors in mm infers we are referring to the diameter of the conductor, some specs seem to infer that it's the cross sectional area - what is it ? )

Ian, I would have to assume he meant to say 'you have got to be a dumb carnt to think you can run flex far enough to NOT consider volt drop, but I could be wrong. I think this thread got going when it considered that too low a voltage puts more stress on motors, so does this now mean the voltage drop IS or IS NOT an issue?

We know the resistance of the cable, we know the voltage drop, so does a 2.2hp compressor, already on the limit for a 10a circuit, have a problem with a 20M extension lead?

I guess we see the problem with offering advice without more detail. Run a 2.4kw bar heater on an extension cable 2m versus 20M? Does the voltage drop matter to the heater? Probably not. Does it matter to a heavily loaded motor. Probably.