2382-622 exam question

[IvayloP]

Hi there. I am a student part time for level 1 &2 in UK. I will have an exam 2382-622 but I stuck to one of the questions. Actually when I looked for information around and make some thinking about it I think the answer would be,B - Maximum demand, because everything else can be directly measured or calculated. Am I right with that though.
I don’t know why the picture can’t be attached. The answers are
A- nominal voltage
B- maximum demand
C- prospective fault current
D- earth fault loop impedance

 

[westward10]

Seeing the question might help.

 

[IvayloP]

Hi there. I am a student part time for level 1 &2 in UK. I will have an exam 2382-622 but I stuck to one of the questions. Actually when I looked for information around and make some thinking about it I think the answer would be,B - Maximum demand, because everything else can be directly measured or calculated. Am I right with that though.

Seeing the question might help.

Yes I agree Just edited it. There was some problem with the picture.

 

[westward10]

Which one of those is a characteristic which can be obtained by enquiry?
I have repeated the question because you need to rule out the three which are not found by enquiry.

 

[mainline]

Hi there. I am a student part time for level 1 &2 in UK. I will have an exam 2382-622 but I stuck to one of the questions. Actually when I looked for information around and make some thinking about it I think the answer would be,B - Maximum demand, because everything else can be directly measured or calculated. Am I right with that though.
I don’t know why the picture can’t be attached. The answers are
A- nominal voltage
B- maximum demand
C- prospective fault current
D- earth fault loop impedance

How would you determine the nominal voltage.

 

[IvayloP]

How would you determine the nominal voltage.

With direct measurements?

 

[IvayloP]

Which one of those is a characteristic which can be obtained by enquiry?
I have repeated the question because you need to rule out the three which are not found by enquiry.

Ehmm the nominal voltage can be measured as well as prospective fault current and earth fault impedance. Let to clarify my view. I am on site and have to connect new house for example. There is the main intake power cable and I can to measure what voltage is present also PFC and earth fault impedance. The thing that I don’t know is how much power the grid company is allowed to be used from it. But in other point of view, the regular electrician like me shouldn’t do that and I will find the main disconnector before the meter and probably two pole switch after it. From the value of the fuse before the meter I will know the maximum demand. Or maybe I missed something

 

[mainline]

Ehmm the nominal voltage can be measured as well as prospective fault current and earth fault impedance. Let to clarify my view. I am on site and have to connect new house for example. There is the main intake power cable and I can to measure what voltage is present also PFC and earth fault impedance. The thing that I don’t know is how much power the grid company is allowed to be used from it. But in other point of view, the regular electrician like me shouldn’t do that and I will find the main disconnector before the meter and probably two pole switch after it. From the value of the fuse before the meter I will know the maximum demand. Or maybe I missed something

Look at 313.1

 

[Tom256]

Ehmm the nominal voltage can be measured as well as prospective fault current and earth fault impedance... Or maybe I missed something

Do you understand the meaning of the word 'nominal'?

 

[IvayloP]

Do you understand the meaning of the word 'nominal'?

What you mean? The nominal voltage on the public supply is 230 for one phase and 400 for three phases. What you understand under public supply? Or you told me that the nominal voltage is the thing that only energy company can give me?

 

[IvayloP]

Look at 313.1

Thanks I will see it later, the book isn’t with me now. The tutor said all information is there but something is still missing to me.

 

[Tom256]

What you mean? The nominal voltage on the public supply is 230 for one phase and 400 for three phases. What you understand under public supply? Or you told me that the nominal voltage is the thing that only energy company can give me?

If you did not know the nominal voltage of the UK, could you take a voltage measurement at the new home in your example and know what it was?

 

[IvayloP]

If you did not know the nominal voltage of the UK, could you take a voltage measurement at the new home in your example and know what it was?

Yes of course. Actually it can be achieved only with seeing the type of the cable but this is less likely to be asked into that exam . Do you think the answer is the nominal voltage?
Wait!! I think I’ve got your point . I can do a direct measurement and will find some voltage there, but I will not know that this is the nominal voltage. The nominal voltage is kind of knowledge or if someone tells you what value it should be. Same as the nominal voltage of appliances you can’t measure it , you only can check the label or ask the manufacturer. Is that true?

 

[Tom256]

Yes of course. Actually it can be achieved only with seeing the type of the cable but this is less likely to be asked into that exam . Do you think the answer is the nominal voltage?
Wait!! I think I’ve got your point . I can do a direct measurement and will find some voltage there, but I will not know that this is the nominal voltage. The nominal voltage is kind of knowledge or if someone tells you what value it should be. Same as the nominal voltage of appliances you can’t measure it , you only can check the label or ask the manufacturer. Is that true?

The question relates to the * supply characteristics * this is the first key phrase. The first consideration is, from the available answers offered, which are characteristics of the supply. That is being tested first, can you identify what are characteristics of the supply.
The maximum demand of the installation is a very important first step aspect of determining the supply intake availability to be provided yet it, in itself, is a characterisitc of the load.

Of the three remaining options if an enquiry is made to the DNO they will provide values for each. However, for the external earth loop and the prospective fault current 'rule of thumb' values from Engineering Recommendations P23 and P25 will be provided to you. (side question: Do you know what they might be?).

The second key phrase therefore is 'NOMINAL voltage'.
The nominal voltage as you say is at a fixed value of 230 volts on a single phase supply, this is stated within the ESQCR, yet it is permitted to be within tolerances of +10% to -6% of that value at the supply intake position. If you take a measurement of the voltage at the intake of the property you could therefore read from 216 volts up to 253 volts.
If you did not know what the nominal voltage was set at then a measurement at the premises would not give you this defined value due to the permitted tolerances.

At least that is the way I am reading the question. Could have it totally wrong but at least I have done as was once always required at school and "show your working out boy".

 

[IvayloP]

The question relates to the * supply characteristics * this is the first key phrase. The first consideration is, from the available answers offered, which are characteristics of the supply. That is being tested first, can you identify what are characteristics of the supply.
The maximum demand of the installation is a very important first step aspect of determining the supply intake availability to be provided yet it, in itself, is a characterisitc of the load.

Of the three remaining options if an enquiry is made to the DNO they will provide values for each. However, for the external earth loop and the prospective fault current 'rule of thumb' values from Engineering Recommendations P23 and P25 will be provided to you. (side question: Do you know what they might be?).

The second key phrase therefore is 'NOMINAL voltage'.
The nominal voltage as you say is at a fixed value of 230 volts on a single phase supply, this is stated within the ESQCR, yet it is permitted to be within tolerances of +10% to -6% of that value at the supply intake position. If you take a measurement of the voltage at the intake of the property you could therefore read from 216 volts up to 253 volts.
If you did not know what the nominal voltage was set at then a measurement at the premises would not give you this defined value due to the permitted tolerances.

At least that is the way I am reading the question. Could have it totally wrong but at least I have done as was once always required at school and "show your working out boy".

Yeah maybe I have a different view about something. In my country when the electrician should make a new DB he must now the maximum demand of the supply , what that main cable and power company can provide. This usually is the amount of the MCB after the meter , the power batch - 10kW, 15kW e t c. Only after that he can do thinking about how the DB will be made and what circuits should include to fit in that. And then the maximum demand of the load comes to each circuit. Maybe this is wrong interpretation because of the two different languages and because of that, that I have knowledge from other country make me to think different on such questions. But thank you about your help. Tomorrow will be my exam, I hope it will be successful. Have a great day

 

[westward10]

B - has nothing to do with supply characteristics.
The answer you are looking for is on page 510 of BS7671.

 

[IvayloP]

Look at 313.1

Because of 313.1 I am stuck on that. They said- shall be determined by calculation, measurement, enquiry or inspection.
Nominal voltage, PSCC , earth fault loop impedance, maximum demand e t c.
And then “the above information should be provided by distributors on request “
So everything from above can be measured or gets from the energy company. But the question is which of these can be ONLY determined from enquiry- and the once that isn’t there is PFC . But it can be achieved when earth fault loop impedance is done with the multimeter or by calculating.

 

[IvayloP]

B - has nothing to do with supply characteristics.
The answer you are looking for is on page 510 of BS7671.

Yes but in EIC all of the four answers are under the supply characteristics, but which of these can only be obtained by enquiry?

 

[westward10]

Do you have BS7671 because the answers is on page 510. B does not fall under supply characteristics, it may be one of the answers but it is not a characteristic.
If you don't have BS7671 then I will post a pic of the page.

 

[IvayloP]

Do you have BS7671 because the answers is on page 510. B does not fall under supply characteristics, it may be one of the answers but it is not a characteristic.
If you don't have BS7671 then I will post a pic of the page.

Yes I have it. The page 510 is EIC certificate. Yes all four answers are under supply characteristics. But the question is which of these can ONLY be obtained by enquiry. Not by measurement or calculation ,only by enquiry the grid company.
By my latest opinion from the answers here I think the nominal voltage Only can be obtained by enquiry.

 

[IvayloP]

Do you have BS7671 because the answers is on page 510. B does not fall under supply characteristics, it may be one of the answers but it is not a characteristic.
If you don't have BS7671 then I will post a pic of the page.

 

[westward10]

Do you have BS7671?

 

[Tom256]

Yeah maybe I have a different view about something. In my country when the electrician should make a new DB he must now the maximum demand of the supply , what that main cable and power company can provide. This usually is the amount of the MCB after the meter , the power batch - 10kW, 15kW e t c. Only after that he can do thinking about how the DB will be made and what circuits should include to fit in that. And then the maximum demand of the load comes to each circuit. Maybe this is wrong interpretation because of the two different languages and because of that, that I have knowledge from other country make me to think different on such questions. But thank you about your help. Tomorrow will be my exam, I hope it will be successful. Have a great day

Yes you need to know the demand when designing in the UK, but as I and Westward have said, the demand is not a supply characteristic it is a characteristic of the load so it can be ruled out. See my post number 14

 

[westward10]

All he need do is look on page 510 of BS7671 the answer is there.

 

[Tom256]

All he need do is look on page 510 of BS7671 the answer is there.

Yes it is.
I wanted to offer him a way of understanding the questions also

 

[mainline]

as I and Westward have said, the demand is not a supply characteristic it is a characteristic of the load so it can be ruled out. See my post number 14

This may have caused him a bit of confusion when trying to omit answer B.

313.1
The following characteristics of the supply or supplies, from whatever source, and the normal range of those characteristics where appropriate, shall be determined by calculation, measurement, enquiry, or inspection:

(v) The suitability for the requirements of the installation, including the maximum demand


These characteristics shall be ascertained for an external supply and shall be determined for a private source. These
requirements are equally applicable to main supplies and to safety services and standby supplies.

 

[IvayloP]

This may have caused him a bit of confusion when trying to omit answer B.

313.1
The following characteristics of the supply or supplies, from whatever source, and the normal range of those characteristics where appropriate, shall be determined by calculation, measurement, enquiry, or inspection:

(v) The suitability for the requirements of the installation, including the maximum demand


These characteristics shall be ascertained for an external supply and shall be determined for a private source. These
requirements are equally applicable to main supplies and to safety services and standby supplies.

Exactly what I meant About that everything can be measured calculated or obtained by enquiry. But guys the question is which of these four things can be ONLY determined by enquiry. Or with other words- which of these cannot be determined with calculation or measurement.

 

[IvayloP]

All he need do is look on page 510 of BS7671 the answer is there.

On page 510 is Electrical Inspection Certificate.

 

[Tom256]

Exactly what I meant About that everything can be measured calculated or obtained by enquiry. But guys the question is which of these four things can be ONLY determined by enquiry. Or with other words- which of these cannot be determined with calculation or measurement.

The maximum demand is needed to ensure the supply provided meets the requirements of the use of the installation.

Anyway, the answer is The Nominal Voltage. The reasons why have been set out if you need more please ask.
Confirmation of this answer is clearly stated on the notes that Westward pointed you towards within page 510

 

[mainline]

Exactly what I meant About that everything can be measured calculated or obtained by enquiry. But guys the question is which of these four things can be ONLY determined by enquiry. Or with other words- which of these cannot be determined with calculation or measurement.

It's not about being able to measure it, as already said its knowing what It's supposed to be.

 

[westward10]

On page 510 is Electrical Inspection Certificate.

Correct and if you look it tells you the answer as to which one of the four it is.
Can we please not give him the answer he needs to find it.

 

[Tom256]

Correct and if you look it tells you the answer as to which one of the four it is.
Can we please not give him the answer he needs to find it.

Understood and quite correct.

 

[IvayloP]

I had to open this sait throgh the computer. So here are the picture ofte question and page 510 from BS7671. Nominal voltage,PFC and Earth fault loop impedance are characteristics of the supply. Maximum demand is characteristic of the load but the question here is - Which characteristic of a public supply can ONLY be determined by enquiry? So here isn't importatnt what is included into the characteristics of the supply,they asked only which of them can't be measured or calculated and only can be achieved by enquiry. This is the way that I understood that qiestion. If the maximum demand isn't supply characteristic so we can exclude it from that, because they asking about the characteristic of a public supply. I hope now everithing is clear. What are your assumptions?
Edit i saw it . There is a little note under nature of supply parameters. Number 1 can be determined only by enquiry,an number 2 enquiry and measurement. So by enquiry Nominal voltage and Nominal frequency, and because there isn't Nominal frequency among the answears the correct answear is Nominal voltage. Someone here led me to that conclusion on previous posts. We can measure the voltage but we wouldn't know that this value is the correct value before it be confirm from power company. Alright guys , thank you about your help. Now I am ready for the tomorrow's exam- I hope

Nominal

 

[Tom256]

What are your assumptions?

I do not understand what you are asking.

 

[IvayloP]

I do not understand what you are asking.

Didn't you see the pictures into the post? Tom you were the person who gave me a clue about the nominal voltage .

 

[Tom256]

All the best in the exam.
Understanding how the questions are worded and what is being asked of you is important in your future exams.

Someone here led me to that conclusion on previous posts. We can measure the voltage but we wouldn't know that this value is the correct value before it be confirm from power company

Pleasure to assist. The key word is Nominal. Taking time to understand the reason will serve you well.

 

[westward10]

Good luck let us know how you get on.

 

[mainline]

Good luck

 

[IvayloP]

I did it guys. Actually this was my second attempt because the first one was fail. I was pretty sure that I had found at least 50 from 60 answers in direct text into the book. There was a technical error at the end of the exam but it seems it was uploaded. After it all system went down and we were unable to do the next four exams. About me sometimes was wrong and about that it was failed. After that I did four times 2382 exams in home and the lowest result was 73% . Today on the sheet was marks achieved 55.000 . I am not sure what does it mean- 55% of 100 or 55 correct of 60 . I can’t believe this is percentage but I don’t know. At least it is successful

 

[Tom256]

Excellent. Well done.