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padawan

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Hey guys, i have started to do some inspecting and testing, i am finding it very interesting although the certification part is a little confusing lol.  To help me i have been out and bought GN3 plus the NICEIC guide to inspecting, testing and certification, but there are some parts i am still a little unsure off so i have got a few questions if you don't mind helping me with, please bare with with me this might be a long read lol.

The installation in question is on a domestic TNS supply. The installation is in a detached garage, which incorporates the supply cable, consumer unit, 16A radial circuit, and 6A light circuit. The supply to the consumer unit is run in 6mm SWA externally and 6mm T&E (plus 6mm single for earth) internally. The 6mm supply cable is protected by a 40A switch fuse, fed with 16mm tails from henrys blocks.

I have got a few questions about filling out the EIC.

1. On page 2 of the EIC under the section SUPPLY CHARACTERISTICS, under sub section ​Characteristics of primary supply overcorrect protectective devices  On the main cut out fuse, there is no clear markings of BS EN number, so i phoned western power to enquire. When i eventually got hold of someone who could supposedly answer my questions, they told me it should be BS 88 part 2, with 16KA breaking capacity (and the Ze was 0.8 ohms for the Ze enquiry test). Its the "should be" part that I'm unsure of, do i need to keep ringing them to get a more definitive answer? Or should i just put down what he said? I was also under the impression that all domestic cut outs were supposed to be BS 1361's?

2. Under the section PARTICULARS OF INSTALLATION AT THE ORIGIN, where you have 4 boxes for:

Measured Ze, Maximum demand, Number of smoke alarms, Protection measure(s) for fault protection.

What do you put in the box entitled Protection measure(s) for fault protection? Is it switch fuse? Or is it RCD/RCCB?RCBO? Or is it EEBADS? Or all of them?

3. Again under the section ​PARTICULARS OF INSTALLATION AT THE ORIGIN, where you have the sub section Main switch/Switch-Fuse/Circuit Breaker/RCD do i fill out the details for the 40A switch fuse, and not the consumer unit RCD?

i.e  BSEN 60947-3, 2 poles, 230v, 40A etc

4.Under the section SCHEDULE OF ITEMS INSPECTED, under sub section 6.0 OTHER METHODS OF PROTECTION 6.1 Basic and fault protection, what do i put for the boxes titled:

a) SELV     LOCATION

b) PELV    LOCATION

c) Double insulated/Reinforced insulation

d) Electrical seperation for one item of equipment

For a) SELV, do i just tick the box? and what do i put in the location box, it is just garage?

For b) PELV do i just put N/A

For c) Double insulated/Reinforced insulation do i tick the box due to the SWA cable? and in location box put clipped direct/underground?

For d) Electrical seperation for one item of equipment do i just put N/A?

5. On page 4 of the EIC, should i put down 3 circuits? and not just 2 circuits for the 16A radial and 6A lights circuit

i.e

1. Garage SUpply

2. Radial Sockets

3. Lights

6. Am i right that the disconnection time for the 3 circuits should 5s for the 40A garage supply, as it is over 32A and a distribution circuit? And the 16A radial and 6A light should both be 0.4s?

7. For the garage supply cable circuit which reference method from appendix 4 do i put? `As the cable is both clipped direct and buired in ducting? Do i put ref C and B?

8. For the garage supply cable circuit do i put number of points served as 1? i.e the consumer unit?

9. For the garage supply cable circuit in the maximum permitted Zs, i am really struggling to find a definitive figure. As the protective device is a 40A 1361 fuse, which isn't listed in the tables in BS7671 or the OSG. I did read somewhere that 1361 fuses have now been reclassified as BS 88 but the only fuses listed are BS 88-3 in table 41.4, but they are 32A and 45A not 40A. There are BS 88 40A fuses listed in table 41.6 but they are for Uo of 55v.

So my question is 2 parts, i) are BS 1361 now classed as BS 88? and ii) as i can't find a tabulated figure 40A BS88? should i use manufacturers instructions, as i found this link with states the Lawson's ME40A fuse stating 1.4 ohm's?

http://help.tradingdepot.co.uk/electrical/lawson-fuses/lawson-fuses-application-data/

10. On the garage supply cable circuit for RCD operating times boxes, do i just put N/A in the boxes?

11. For the 16A radial circuit, for the maximum Zs permitted by BS7671 do i put 2.73ohm's as stated in table 41.3 for type B 60898 breakers?

12. For the 6A light circuit, for the maximum Zs permitted by BS 7671 do i put 7.28 ohm's as stated in table 41.3 for type B 6088 breakers?

13. Am i right that as if i do R1 + R2 test, i then don't have to also do R2 test?

14. For the box Maximum measured earth fault loop impedance Zs, when i do Zs test on the radial circuit and light circuit by linking Phase and CPC and testing between Phase and CPC at each accessory point, do i take the highest reading as my Zs value?

The reading i am getting is 0.31 ohm's,

and since  Zs = Ze + (r1 + r2) 

                 Zs = 0.22 + 1.34

                 Zs = 1.56

So surely my reading should be 1.56 ohm's not 0.31 ohm's

Sorry for the war and peace post, and sorry for so many questions, i hope you don't mind answering all my questions and can excuse my ignorance but i am learning haha

Cheers

 
Hey guys, i have started to do some inspecting and testing, i am finding it very interesting although the certification part is a little confusing lol.  To help me i have been out and bought GN3 plus the NICEIC guide to inspecting, testing and certification, but there are some parts i am still a little unsure off so i have got a few questions if you don't mind helping me with, please bare with with me this might be a long read lol.

The installation in question is on a domestic TNS supply. The installation is in a detached garage, which incorporates the supply cable, consumer unit, 16A radial circuit, and 6A light circuit. The supply to the consumer unit is run in 6mm SWA externally and 6mm T&E (plus 6mm single for earth) internally. The 6mm supply cable is protected by a 40A switch fuse, fed with 16mm tails from henrys blocks.

I have got a few questions about filling out the EIC.

1. On page 2 of the EIC under the section SUPPLY CHARACTERISTICS, under sub section ​Characteristics of primary supply overcorrect protectective devices  On the main cut out fuse, there is no clear markings of BS EN number, so i phoned western power to enquire. When i eventually got hold of someone who could supposedly answer my questions, they told me it should be BS 88 part 2, with 16KA breaking capacity (and the Ze was 0.8 ohms for the Ze enquiry test). Its the "should be" part that I'm unsure of, do i need to keep ringing them to get a more definitive answer? Or should i just put down what he said? I was also under the impression that all domestic cut outs were supposed to be BS 1361's?

You will get the hang of this with experience, however you can put BS88 with a note on your certificate that this was established by enquiry. In some cases whilst not 'proper' it is possible to put LIM

2. Under the section PARTICULARS OF INSTALLATION AT THE ORIGIN, where you have 4 boxes for:

Measured Ze, Maximum demand, Number of smoke alarms, Protection measure(s) for fault protection.

You already know the answer to this if you think about it, is it one measure or multiple measures that are all contributing to disconnection of supply in the event of a fault, is this manual or automatic?

What do you put in the box entitled Protection measure(s) for fault protection? Is it switch fuse? Or is it RCD/RCCB?RCBO? Or is it EEBADS? Or all of them?

3. Again under the section ​PARTICULARS OF INSTALLATION AT THE ORIGIN, where you have the sub section Main switch/Switch-Fuse/Circuit Breaker/RCD do i fill out the details for the 40A switch fuse, and not the consumer unit RCD?

i.e  BSEN 60947-3, 2 poles, 230v, 40A etc

It is the ORIGIN, that is where the supply enters the building.

4.Under the section SCHEDULE OF ITEMS INSPECTED, under sub section 6.0 OTHER METHODS OF PROTECTION 6.1 Basic and fault protection, what do i put for the boxes titled:

a) SELV     LOCATION

b) PELV    LOCATION

c) Double insulated/Reinforced insulation

d) Electrical seperation for one item of equipment

For a) SELV, do i just tick the box? and what do i put in the location box, it is just garage?

For b) PELV do i just put N/A

For c) Double insulated/Reinforced insulation do i tick the box due to the SWA cable? and in location box put clipped direct/underground?

For d) Electrical seperation for one item of equipment do i just put N/A?

This is a big question, you only fill out any boxes if you have installed or used that means of protection. You must read the books you have bought as this question could take an hour to fully explain and understand.

5. On page 4 of the EIC, should i put down 3 circuits? and not just 2 circuits for the 16A radial and 6A lights circuit

i.e

1. Garage SUpply

2. Radial Sockets

3. Lights

It is good practice to inspect and test all circuits you are working on and that would mean the supply cable as well.

6. Am i right that the disconnection time for the 3 circuits should 5s for the 40A garage supply, as it is over 32A and a distribution circuit? And the 16A radial and 6A light should both be 0.4s?

Again you know the answer but doubt yourself, confidence will come with experience.

7. For the garage supply cable circuit which reference method from appendix 4 do i put? `As the cable is both clipped direct and buired in ducting? Do i put ref C and B?

As a rule I always put the reference method down for the longest run over any method, however if any derating is higher I will always include that in my assessment.

8. For the garage supply cable circuit do i put number of points served as 1? i.e the consumer unit?

Yes

9. For the garage supply cable circuit in the maximum permitted Zs, i am really struggling to find a definitive figure. As the protective device is a 40A 1361 fuse, which isn't listed in the tables in BS7671 or the OSG. I did read somewhere that 1361 fuses have now been reclassified as BS 88 but the only fuses listed are BS 88-3 in table 41.4, but they are 32A and 45A not 40A. There are BS 88 40A fuses listed in table 41.6 but they are for Uo of 55v.

So my question is 2 parts, i) are BS 1361 now classed as BS 88? and ii) as i can't find a tabulated figure 40A BS88? should i use manufacturers instructions, as i found this link with states the Lawson's ME40A fuse stating 1.4 ohm's?

http://help.tradingdepot.co.uk/electrical/lawson-fuses/lawson-fuses-application-data/

Again this is where you need to research and ask around when not sure.

10. On the garage supply cable circuit for RCD operating times boxes, do i just put N/A in the boxes?

If there is no RCD then yes

11. For the 16A radial circuit, for the maximum Zs permitted by BS7671 do i put 2.73ohm's as stated in table 41.3 for type B 60898 breakers?

Again read your books you purchased the answers are all there.

12. For the 6A light circuit, for the maximum Zs permitted by BS 7671 do i put 7.28 ohm's as stated in table 41.3 for type B 6088 breakers?

As above

13. Am i right that as if i do R1 + R2 test, i then don't have to also do R2 test?

No you are wrong, if you look at the forms it states 'For all circuits' this would imply that a R2 reading is required.

14. For the box Maximum measured earth fault loop impedance Zs, when i do Zs test on the radial circuit and light circuit by linking Phase and CPC and testing between Phase and CPC at each accessory point, do i take the highest reading as my Zs value?

The reading i am getting is 0.31 ohm's,

and since  Zs = Ze + (r1 + r2) 

                 Zs = 0.22 + 1.34

                 Zs = 1.56

So surely my reading should be 1.56 ohm's not 0.31 ohm's

You always record the highest reading, there is a very good reason why your measured reading is lower than your calculated. What do you think would make it lower? There are possibly two of these in the building you are inspecting.

Sorry for the war and peace post, and sorry for so many questions, i hope you don't mind answering all my questions and can excuse my ignorance but i am learning haha

Cheers

See my red and have a good read of your books.
 
for the suppliers fuse I always put down  N/V  [not verified]

as, if I cannot physically determine it myself then I cannot state it to be, and, as we are not permitted to pull the cut-out fuse then I cannot verify what it is.

 
I was filling out a cert the other day and looked at the main fuse, someone had helpfully written '80A IIb' on the side of the fuse carrier. On closer inspection I realised it was my handwriting, I must remember to do that more often!

5. On page 4 of the EIC, should i put down 3 circuits? and not just 2 circuits for the 16A radial and 6A lights circuit

i.e

1. Garage SUpply

2. Radial Sockets

3. Lights
Fill the cert in for the board in the house, use a continuation sheet for the garage board.

 
13. Am i right that as if i do R1 + R2 test, i then don't have to also do R2 test?

No you are wrong, if you look at the forms it states 'For all circuits' this would imply that a R2 reading is required.

Am I reading this right? It doesn't state ring or radial. So for radial circuits you don't always have to record R2. It's stated in the OSG dependant on which test method you've employed?

 
I am not wrong just use a form with obviously more information required than the one's you use. On my certificates it has 5 columns for circuit impedance.

3 for ring circuits r1 rn and r2 then 2 for what the header describes as ' all circuits' r1+r2 and r2.

Therefore my statement is correct.

 
But you don't have to do both though, if your form said do Ze whilst wearing only one shoe it wouldn't make it a requirement.

 
Not exactly Lurch, however I do not like to leave any blank or unfilled columns on my certificates as it looks like you have not bothered. I know you could put N/A but it only takes a couple of minutes to actually do the test and fill in a value. It is also a valuable reading to have when you come to fault finding for instance at a later date.

 
I'm not disagreeing with that and you can do whatever you want, but it still doesn't make it a requirement. If you are going to say both R1+R2 and also R2 are required you should qualify it by saying it is your own personal preference and not a requirement of the regulations.

 
I wasn't saying you where wrong I just questioning your statement. :B-

My certs have 5 columns same as the ones you use as they are copies of the ones in the BYB. They don't state 'all circuits'. As Lurch has pointed out recording R2 isn't a requirement of BS7671 so the OP wasn't wrong with his statement in point 13.

 
I will stand by my statement. I recall in the back of my mind the words that make me test and subsequently record r2. I do however take your comments on board and acknowledge them.

 
The model forms in BS7671 state

"Continuity

(ohms)

(R1+R2)

or R2"

So whilst you may like to do both (and it may be a valuable reading to record) it isn't a requirement

 
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