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This is the On Site Guide to BS7671

@@ElectricalStudentsUK do you have a link to purchase the book I'm starting to do more testing and I'd like to read up on more just to keep up the standard !!

@nateryan7041 Here it is from amazon. Chapter 10 is testing www.amazon.co.uk/Site-Guide-7671-Electrical-Regulations/dp/1839532270/ref=mp_s_a_1_1?crid=2KA48ABV0R3IH&dib=eyJ2IjoiMSJ9.CmFov_R1ObmOJvcm_VkNDZYKGHNeakacLk3liDRpTCjc7tAdTZmRUvefNeMO1QECUCymwNujty5pDnYYQKkbtZi7319OCD3BwzHu1k4haegDkc77HWsBt5xGrl4P8hF5W9evggftMINmsuKnyBTf1DTY_TiYOUH__6rdraw-slVH6bIUDiEEjz5hhxgAaaL-1tvucKQaTlOnqofOSreJfw.tDLEThCY61VSoLESpvyNW83cTHNo_Ra0KHC48lUAhAc&dib_tag=se&keywords=on+site+guide+electrical+2024&qid=1724526865&sprefix=on+sire+guide%2Caps%2C209&sr=8-1 For more detailed testing read Guidance Notes 3, although this is aimed at a 'test and inspection qualified electrician. www.amazon.co.uk/Guidance-Note-Inspection-Electrical-Regulations/dp/183953236X/ref=mp_s_a_1_1?crid=1QW6AMLLDOZ3N&dib=eyJ2IjoiMSJ9.EB6IxV44MWZxPOCoxiKybHE6w9Vh4Y303Y0BL2neSpaKz0p9it0Nb7TUwnF75c47q6gwByl518szeqMkz2sqL9gNLQsmLj0bOSTF_Yww_hRtMLlihbJ5kOgltcHo53rwfeMiVzBsd6j1CyF9fZreGqPUPFydiNTxDxQOKPhkYwtN13DhMiNYzehQJJOowAHSkSS27ZlwELVIPv5-3-1xbQ.kmZpGsceMHVwmNqsnJq8HjUOt9DJXE1OBiUZ3hvFBq4&dib_tag=se&keywords=guidance+notes+3&qid=1724527047&sprefix=guidance+notes+3+%2Caps%2C81&sr=8-1

Hi, a closer look at the picture shows a three phase supply to the board. But the final circuit to the lights is a single phase. Imagine a commercial or industrial property. Three phase supplies to the boards, but the lighting and power final circuits from those boards would be single phase

@Badger8169 Thanks! Have a read of page 118 OSG. You should remove lamps, test, then operate any 2 way switches, test again. This is due to possibly damaging customers lamps with a 500V test. Also the second test is to test the other cables used in two way switches. Known as the strappers. I haven't any videos with flukes. I've used flukes and find them really complicated for a first time user.

@@ElectricalStudentsUK Ive bought a fluke 1664 fc and struggling ! think i should have bought a megger as all demonstrtations seem to be with one thanks for the reply

👋 😂 sorry pal. Promises it is tripping!

I have been a qualified electrician for thirty eight years. Point one what is an accredited. There is no legal requirement or regulation requirement for any spark to be registered/accredited . Never has been. The purpose of the RCD test is to determine if it will trip within a specified time ie at 1x its rated current we expect it to trip in less than 300ms at 5x in less than 40ms . We can test at the socket or the CU . If you already know what the Ze and Zs values are and you want to know the the RCD will operate at we do a ramp test which will tell how much current it takes for the RCD to operate.

Watch the video again. He did the test correctly. He clearly tested the lighting circuit and he probed onto the outgoing side of the MCB . If he did what you are talking about then he would test at the top of the RCD ie green lead on the earth bar brown probe on the RCD line and blue probe on the RCD Neutral. .

It is difficult to make videos for different levels. If you're doing a cable calc from the OSG, then it's basic and you will be a level 2 student. When you start using BS7671, you'll be completing a much more indepth cable calculation, using all of the correct tables, depending on what type of cable you have. My videos are aimed at college students who are just starting out in their career. Which is another reason I'm trying to expose them to the many different C factors and reference methods. I'm glad you've found the video helpful in some way! 😊

The Green earth lead goes in the green L2 port on the back of a Megger Multifunction tester. Other testers will he different. You do not double the value for 3 phase. The earth fault current will only travel down one of the phase cables in 3 phase, to activate the protective device. Therefore even in 3 phase, the calculated Ipf will always be 230/Zs

Your teacher is indeed correct. Some voltage sensitive devices such as an OVR and even some RCBOs can be damaged having 500V put through them. You are also correct, if your installation is a simple one, with no voltage sensitive equipment, like my small test board in the video, then it is fine to test the entire board this way. Look in Chapter 10 of your OSG and it gives pictures on performing this test

@@ElectricalStudentsUK Thank you!

Thank you, I hope my explanations help with your learning journey

@@SpinSkins your explanation really helped me understand some things that were Ambiguous to me. Thanks 🙏

See post above. The test you have performed is incorrect and is only testing the RCD for the DB and is not recorded on the sheet you have used. The RCD test for a circuit should be carried out at the furthest point of the circuit. This will take into account the circuit resistance R1+R2 and Rn. The test you carried out is only using the external impedance Ze at the DB and not the fault circuit as a hole. The aim of the test is to take the total resistance of the circuit, the fault path, which will determine how quick the RCD will trip under fault conditions, the higher the resistance the slower the trip time. Therefore the RCD test requires to be done on every circuit and recorded in the location you used. The test you carried out is recorded on sheet 2 under, Main switch / Switch Fuse / Circuit breaker / RCD, under "If RCD main switch". I would take this done before someone gets hurt and is traced back to your UA-cam. I am retired now but I am an Accredited Electrician.

Hi there, if you're doing the correct cross connections for the R1 + R2 test, as shown on p117 OSG. Then that reading is the correct R1 + R2 value. The test you would have done before, the end to end test for live, neutral and earth. Its those values, if you add the live and earth end to end value together, then divide by 4. You should get the same as the R1 + R2 value.

Brilliant thank you so much mate

Ring circuit do you mean to do your L-L , N-N and CPC -CPC for step 1 And step 2 and 3 you do R1 +Rn and R1 +R2 but use the plug on the socket to step the process?????

@@SpinSkins Would you know the formula on how to work out the Iz of a 4mm ring circuit?

Thank you mate, glad my videos help you

Yes you remove all sensitive devices and also if you had a fault within a circuit you only did live to earth not live to neutral, good presentation but more detail needed

The RCD setting on most tester will test any type of RCD. You only need to change the mA setting that matches the mA rating of your RCD

No you are only required to test the RCD/RCBO on the Ac setting at it rated close ie 30ma regardless of what type the RCD is and you only need to test at one times half time and five times test is no longer required.you can do them if you want to but you are not required to do them.

If you do not know the size of the cpc, then you match it to the size of the line conductor. In this instance, the live was 6mm. Looking at table I1 OSG, the milli ohm per metre value of 6mm live and 6mm earth is 6.16. This value is used to find out R1+R2 which eventually leads to the adiabatic equation of calculating S, the minimum csa size of the cpc

Thank you@@ElectricalStudentsUK

Yes well spotted! Sorry for my mistake

Thanks for your informative educational videos. 👍

No worries mate. Anything you're unsure of and want me to go over for you, let me know

Are you doing level 2 or level 3?

@@ElectricalStudentsUK level 2 & 3 😁

​@Djredsielofficial Good pal, check out the website www.electricalstudent.co.uk for loads of mock test questions, all formula sheets and guide sheets to help with all of your exams!

@ElectricalStudentsUK Thanks mate . signed up mate Waiting for confirmation 👍

No worries. Glad the video has helped you

This video will really help you, check out my level 3 formula videos when you start the maths and scientific principles module. There are formula sheets and a step by step cable calculations guide in my shop at www.electricalstudent.co.uk They will be really helpful to you

Hi pal. They are exam style questions I make up for students like you. For more exam style questions, formulae sheets and guides, check out www.electricalstudent.co.uk

Hi am just wondering when you add up the total I got 188.8 I don't understand how u got you're answer can you please show me thank you

​@craigrod5728 you have added the first 12.43. Only add everything that has been underlined. Using diversity, you only use 75% of 12.43, which is 9.3. When totaling up the maximum demand, we only include the 9.3, not the 12.43

Oh ok got that thanks

Glad to have helped you pal. Head over to www.electricalstudent.co.uk to find more tips and guides to help you pass your level 3 exams. Good luck in your upcoming exams!