Britains diesel scandal

[alanaslan]

Originally Posted by mss

Your units of CSA are all over the place. The correct units to use are, as an example, 10mm^2 (pronounced 10 square mm). To state 10mm squared means a CSA that is equivalent to 10mm by 10mm. To state 10mm CSA is meaningless.


You have also got the charging principles somewhat upside down.

Car batteries do not take 80% of their charge during the first hour. Rather, the batteries are designed to be fast charged such that if the charger is capable of supplying the necessary current, they can take a charge equal to 80% of the battery capacity in one hour. This scenario is relevant to the fast charge points provided at motorway service stations but not at home.

Home charge points are designed to charge at or below 7KWh over a period of about 8 hours i.e. overnight. If you now compare this with the electricity consumed by a cooker with the oven and all rings in operation or, indeed, your electric shower, the scenarios are comparable.

This means that the cable to the charging point has to be suitably sized, as is the case for a cooker or a shower, but the scope of the problem is not anything like you state.

We radio control boat modellers have been using different charging rates since about 1980 - 30 or 60 minute charging at the field and overnight charging at home. This is nothing new.

For anyone really keen, this is the definitive authority document in the UK for configuring charging installations.

IET: Code of Practice for Electric Vehicle Charging Equipment Installation 2nd Edition

Strange CSA is the standard used in the 14th, 15th, 16th, 17th and the new 18th edition. The problem with people today is they understand what things actually mean.
A classic historical example of this wound be the old “ Highly Inflammable” this was meant to mean that something was easily combustible ie would burn easily. We used this for over 70 years in the UK till we saw the error of our ways.
A 10mm by 10mm would be a new one on me I have never seen o square cable and the CSA of such a cable would be 100mm.
When you buy cable it is sold in CSA sizes.
This has always been one of my fears when we do rewrites of IEE regs, we are making the assumption that people who are using the book have a basic understanding of maths and understand where pie comes into the equation.
It used to be worse when we used concentric cable with a neutral wrap and an earth wrap then the final internal insulator before the wire outer and rubber cover.
My understanding of electric vehicles comes from speaking to the designers. I don’t dispute that my information is eight years old, as I have let things slip since I retired.
I have however taken from your post that their is a lack of basic understanding when it comes to IEE regs and will make this known to the revision committee, we will try to make these things easier to understand in the second reprint of the eighteenth edition. We will also look into changing the City and Guilds lecture pack as it seems we have failed to convey the way we measure the conductor size of electrical cable. I would like to hear your views on multi core electrical wire ie SWG. Please let me know not on the form but by email at [email protected]
I am assuming that you are either an electrical engineer or an electrician. As our publications are meant to be easily understood, and all exams are open book. If we have failed in this. Then we need to look carefully at how we write them in future.



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[alanaslan]

Originally Posted by mss

Cable diameter of 16mm? Not unless you are running a power station.

The point I was making is that there is not such measure as Xmm CSA or CSA of Xmm. It is CSA of Xmm^2 (pronounced X square mm)

You can then work backwards to calculate the diameter using the equation

CSA = Pi r^2, where r = d/2

Spot on


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[MSS]

Originally Posted by alanaslan

Strange CSA is the standard used in the 14th, 15th, 16th, 17th and the new 18th edition. The problem with people today is they understand what things actually mean.
A classic historical example of this wound be the old “ Highly Inflammable” this was meant to mean that something was easily combustible ie would burn easily. We used this for over 70 years in the UK till we saw the error of our ways.
A 10mm by 10mm would be a new one on me I have never seen o square cable and the CSA of such a cable would be 100mm.
When you buy cable it is sold in CSA sizes.
This has always been one of my fears when we do rewrites of IEE regs, we are making the assumption that people who are using the book have a basic understanding of maths and understand where pie comes into the equation.
It used to be worse when we used concentric cable with a neutral wrap and an earth wrap then the final internal insulator before the wire outer and rubber cover.
My understanding of electric vehicles comes from speaking to the designers. I don’t dispute that my information is eight years old, as I have let things slip since I retired.
I have however taken from your post that their is a lack of basic understanding when it comes to IEE regs and will make this known to the revision committee, we will try to make these things easier to understand in the second reprint of the eighteenth edition. We will also look into changing the City and Guilds lecture pack as it seems we have failed to convey the way we measure the conductor size of electrical cable. I would like to hear your views on multi core electrical wire ie SWG. Please let me know not on the form but by email at [email protected]
I am assuming that you are either an electrical engineer or an electrician. As our publications are meant to be easily understood, and all exams are open book. If we have failed in this. Then we need to look carefully at how we write them in future.



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Hi Alan,

Thanks for your really helpful post. Also, reading my original response to yourself, it will have come across as being a little terse. That was not my intention but I typed it in between lawn mowing duties and in a hurry. So my apologies for the tone of the response.

I am not an electrician but an engineer - I studied City & Guild in General Engineering, followed by an ONC in Engineering & Technonogy and then a BSc degree in Computer Systems & Electronics but also took all the optional modules available in Power Systems/Networks and Microwave Engineering. Then followed it up with a Masters in Advanced Digital Communications and Signal Processing. So, whilst being practically biased, I also enjoy the engineering application of mathematics in some depth, hence my desire to ensure precision in terms of units and the size of cables.

The IET regs are fine and outstandoing pieces of work. It is the trade that is responsible for much of the confusion . They use terms like 10mm cable, which non-trade people then translate into either 10mm outer measurement or, as in the case of a number of posts here, 10mm conductor diameter. I don't think the engineering professionals such as yourself will ever be able to curtail such heresy.

Given your role in the regs, I hope we meet one day as we could natter endlessly about such things . I have just finished my 37-year career in the design and delivery of signal processing systems and telecommunication networks. Earlier in my career, I used to be part of the UK delegation at CCITT SG17 that defined world modem modulation and coding standards and documented them for inclusion in the red books. So I can fully understand the challenges that you face.

Take care.

[MSS]

Originally Posted by Darcydog

I think the response from Maninder above says it all.

Inflated ego and bu99er real knowledge or ability to read what is there.

In my experience one sometimes comes across people who feel that they should be much bigger and better than they are. When they realize that this is beyond their capability, they attack those who actually are better than them.

This is nothing new and unfortunately we see it in relation to may topics. An example would be the diesel and 1.8k drivers who keep highlighting V8 engined cars with headlines that they are not worth the money.

Such is human nature!

[alanaslan]

Originally Posted by mss

Hi Alan,

Thanks for your really helpful post. Also, reading my original response to yourself, it will have come across as being a little terse. That was not my intention but I typed it in between lawn mowing duties and in a hurry. So my apologies for the tone of the response.

I am not an electrician but an engineer - I studied City & Guild in General Engineering, followed by an ONC in Engineering & Technonogy and then a BSc degree in Computer Systems & Electronics but also took all the optional modules available in Power Systems/Networks and Microwave Engineering. Then followed it up with a Masters in Advanced Digital Communications and Signal Processing. So, whilst being practically biased, I also enjoy the engineering application of mathematics in some depth, hence my desire to ensure precision in terms of units and the size of cables.

The IET regs are fine and outstandoing pieces of work. It is the trade that is responsible for much of the confusion . They use terms like 10mm cable, which non-trade people then translate into either 10mm outer measurement or, as in the case of a number of posts here, 10mm conductor diameter. I don't think the engineering professionals such as yourself will ever be able to curtail such heresy.

Given your role in the regs, I hope we meet one day as we could natter endlessly about such things . I have just finished my 37-year career in the design and delivery of signal processing systems and telecommunication networks. Earlier in my career, I used to be part of the UK delegation at CCITT SG17 that defined world modem modulation and coding standards and documented them for inclusion in the red books. So I can fully understand the challenges that you face.

Take care.

Thanks, I have noticed over the passed ten years during the last two reprints of the 17th edition we had a great many domestic sparks failing their exams.
I feel part of this increase must be due to the way we have written the books. As the exam are open book the candidate has access to all the information they need to answer the questions correctly. Perhaps it needs us to understand those taking the courses better.
I have always found it difficult to put myself in a place where no prior knowledge is assumed.
Further to this the trades way of describing different conductors, wires, cables, SWA, T&E, flexes, single core conductors, multi core conductors.
To many it must seem very confusing. I wish we knew a way to simplify the whole thing.
Thank you for being so understanding.
Alan


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