Good stuff. I generally (on an non-energised installation), disconnect the main protective bonding conductors at the MET individually so as not to pick up any parallel paths. If I'm wrong here, please correct me. 👍
Mike, you're not wrong, either end will do. I usually go for the pipework end as I want to check bonding clip to pipework anyway. The point I wanted to make to the new guys was that you must disconnect one end to eliminate parallel paths. Keep your comments coming, it all helps. Dave.
@@learnelectrics4402 Morning Dave. Yeah, I totally agree with you and your teaching method is spot on. Everybody is different in their approach and, as the youngsters coming through will soon find, the perfect environment of a classroom doesn't always relate to what you see on site. The only problem with disconnecting anything at a consumer unit/distribution board or MET is FORGETTING TO RE-CONNECT IT! Dave, you're doing a fantastic job you really are! Keep it up mate. 👍
What I tend to find is that new combi boilers will have built in supplementary bonding across the pipes, therefore if there is any connection between the bonding conductors (either via pipes or MET) that you tend to get continuity readings. To avoid this I try to disconnect both ends.
@@learnelectrics4402 I wonder if a good video would be to discuss determining whether bonding and earthing can be deemed as "adequate" as per the regulations requirement prior to carrying out any work. I often find bonding in the wrong place or under-sized earthing in the context of todays regulations and its often a barrier to getting some smaller jobs when it needs to be done.
tested this on my house,gas water pipes,with my megger,and worked out nice,made wander lead too,messure its resistance and marked on the roll ,had wander round house too and messure earths at sockets ,lights,garden shed,pond water fall power point ,good stuff to know ,love the old school sparks,know there stuff
Thanks Richard, great feedback. So glad its useful and I love it when someone actually goes and tries the suggestions. This is a good trade to be in, its taken me around the world several times. Lot's more to come, Dave.
@@learnelectrics4402 hi ,i use be a sparky ,left school 1985,thacher was in power,school leavers had yts,so i worked with my uncle,he got laid of from airbus,as a spark ,and set up on his own,i help him out and we did house bashing,sheds,garages,i got good at it after few years ,and he said i should go to collage ,be proper spark,so i did ,had 6 years at collage ,and the exam questions ,as i was taught practical by him,i visulise me doing the question on site,so work out what the answer was ,had high pass rate too,reason i watch this vid was i had high earth leakage on split consumer unit and to much hanging of 1 rcd ,earth leagage test was near the limit ,trip point ,so i rip out the board and fit rcbo instead ,had cross neutral too,you reminded me so much of my uncle ,and how he explain stuff,when on a job ,he say what customer wanted done ,and ask me to work it out ,parts,costs,time ,then he see if i made mistakes,also i had to draw circuit diagrams of how i would wire it up ,cable size,fuse,switch ect,use the nic eic book for ref ,and said iron out the mistakes at first step,his teaching methoud help me out over the years,and i help other sparks too,one had put in intermediate switches on a 2 way ,and got it wrong ,so i show him the draw a diagram way,calc runs,and he fixed it easy then , prefer 3 phase ,amour and cable trays to house bashing ,but work is work,my uncle retired now and designs wiring for hotels,warehouse ,building sites,still got my megger,old but works fine,r1 r2 zs tests ir 500v tests,wish i could of work with you ,would learn so much ,love the older sparks,they never seem stressed,just test and work out problem ,i check out the rest of your vids,refresh myself ,voltage drop over distance is another one i like ,long power cable to shed,and tt earthing ,data lines too,internet ,not done much cctv,but fitted sat dishes ,sky and polsat ,keep up the good work ,you are helping young and old sparks out ,earn good merit
Great video - another video on supplementary EB would be useful as this is often misunderstood leading to unnecessary proliferation of clamps and short green and yellow wires. An explanation of what constitutes simultaneously accessible exposed conducive parts and exposed conducive parts would be great 👍
Brilliant stuff again dave 👍👍 an update dave, I’ve enrolled at local college and start in September level 2-3 2365 c&g 👍👍 I cant wait and I’ll probably keep going over your videos as they really are good learning 👌👌 as most have said thank you very much, keep them coming 🙌🏻🙌🏻
That's fantastic news. It really is a great trade to be in and its taken me all over the world. hard work but great experiences. You'll do well at college I'm sure because you WANT to learn. Keep watching the videos, even watch them twice or more. I always say that a dripping tap will fill a bucket. You've got about 200 days before college, just think how much extra you will know by then. learn as much as you can buddy and enjoy college, its worth it. I've enjoyed the last 45 years in this game. take care, keep in touch. Dave.
@@learnelectrics4402 Love this saying " dripping tap will fill a bucket" .I remember I've really struggled when been doing Project for 2365 Level 3 with Adiabatic Formula, shame a haven't seen your video than... It looks like every college has its own preferences for a testing procedure for testing. We've only done a continuity test on earthing clump and copper pipe, I see now why you have to physically remove bonding .. Thank you Dave. I'm listening to your channel every day as I;'m going to work. Keep coming with new videos!👏🏻👏🏻
Dear sir the 16mm calculation not matching the calculation can recalculate and correct that please. Thank you for your video it fantastic and happy new year
Check your calculation and the order that you put the data into your calculator. Square root comes at the beginning of the written calculation but you need to do square root at the end.
What determines the max fault current that can flow. We calculated the max allowed for a disconnection 0.4 seconds that does not overheat the cable. Is it the prospective fault current ?
All the resistances in the circuit affect the current flowing. If its a water heater it will be 230 volts divided by the resistance of the cables to the heater plus Ze, in other words Zs for the heater circuit. Prospective Fault current is measured at the Consumer Unit as this is the worst case position. i.e 230 volts divided by Ze. Dave.
If it is difficult to access the bonding clamp, (e.g. hidden in the floor, but appears good visibly) could you also reverse the test by disconnecting all the earthing conductors at the consumer unit bus bar and test the individual earthing cables from the end at the CU to the other end e.g. by a bathroom radiator?
@@learnelectrics4402 I think that was what I was trying to say, same as the video just from the other end? I notice in new builds they often have the earth bonding on show in bathrooms by the radiators but this is quite unsightly. Is it OK to place this below floor level as long as tests ok? I'm theory you can service by cutting a hole in the ceiling from below.
dear sir the you calculation 16mm cps its not matching with my calculation can you recalculate or may be some errors I have try your formula but not same answer so I will be happy if explain thank you very nice explain step by step it very helpful . thank you
Check your calculation and the order that you put the data into your calculator. Square root comes at the beginning of the written calculation but you need to do square root at the end.
Hi. can you tell me please, where can i find answer for this question on amedment2 WR book? an earth busber connected to a 250A per phase supply, must not be thans 1. 50mm2 2.16mm2 3. 10mm2 4. whatever the guidance 54.8 explain i know its in chaper 54 but i cant find answer. can you give me more information or i have to use calculation form?
Does a oil boiler incoming pipe need bonded if it comes into outhouse with copper pipe but insulated with white coating at point of entry? If it does need bonding what size of cable.
Can I ask a question please about size of earth please. How do you choose correct size earth for fly lead from banjo on an swa where armourings are the cpc?? Many thanks
The fly lead should be the same size as the conductors or a minimum size of 2.5mm inside the housing or 4mm if connected outside the distribution board or housing. Hope this helps. Dave.
@LEARN ELECTRICS Thanks Dave. Everytime I've seen a fly lead from swa it's on inside of DB from banjo and thought people just used 6mm as standard regardless of size of swa. He certainly asking what size should be
Thanks for the video. My maths isn't what it used to be but I agree with the 6mm answer (1090 amps) but get different answers for 10mm (1818 amps) and 16mm (2909amps). Am I missing something?
Thanks Grumpy G. You are correct as is Terence. I think that was the calculator that I actually threw in the bin yesterday, I suspected it was faulty and bought a new one today. I know the story of blaming your tools but that's the truth on this occasion. Anyway, so glad you actually tried the calculation. I'll correct it. Dave.
Thanks Terence, yes, you and Grumpy G are right. That calculator is now in the bin - seriously - it kept failing on me. New calculator bought today and I agree with your results. Good practice for you, and thanks for the heads up. Dave.
Excellent tutorial as ever from Learn Electrics. Clear, consice instructions and diagrams. Many thanks
Glad you liked it and thanks for the support. Dave.
Good stuff. I generally (on an non-energised installation), disconnect the main protective bonding conductors at the MET individually so as not to pick up any parallel paths. If I'm wrong here, please correct me. 👍
Mike, you're not wrong, either end will do. I usually go for the pipework end as I want to check bonding clip to pipework anyway. The point I wanted to make to the new guys was that you must disconnect one end to eliminate parallel paths.
Keep your comments coming, it all helps. Dave.
@@learnelectrics4402 Morning Dave. Yeah, I totally agree with you and your teaching method is spot on.
Everybody is different in their approach and, as the youngsters coming through will soon find, the perfect environment of a classroom doesn't always relate to what you see on site.
The only problem with disconnecting anything at a consumer unit/distribution board or MET is FORGETTING TO RE-CONNECT IT!
Dave, you're doing a fantastic job you really are! Keep it up mate. 👍
What I tend to find is that new combi boilers will have built in supplementary bonding across the pipes, therefore if there is any connection between the bonding conductors (either via pipes or MET) that you tend to get continuity readings. To avoid this I try to disconnect both ends.
@@learnelectrics4402 I wonder if a good video would be to discuss determining whether bonding and earthing can be deemed as "adequate" as per the regulations requirement prior to carrying out any work. I often find bonding in the wrong place or under-sized earthing in the context of todays regulations and its often a barrier to getting some smaller jobs when it needs to be done.
tested this on my house,gas water pipes,with my megger,and worked out nice,made wander lead too,messure its resistance and marked on the roll ,had wander round house too and messure earths at sockets ,lights,garden shed,pond water fall power point ,good stuff to know ,love the old school sparks,know there stuff
Thanks Richard, great feedback. So glad its useful and I love it when someone actually goes and tries the suggestions. This is a good trade to be in, its taken me around the world several times. Lot's more to come, Dave.
@@learnelectrics4402 hi ,i use be a sparky ,left school 1985,thacher was in power,school leavers had yts,so i worked with my uncle,he got laid of from airbus,as a spark ,and set up on his own,i help him out and we did house bashing,sheds,garages,i got good at it after few years ,and he said i should go to collage ,be proper spark,so i did ,had 6 years at collage ,and the exam questions ,as i was taught practical by him,i visulise me doing the question on site,so work out what the answer was ,had high pass rate too,reason i watch this vid was i had high earth leakage on split consumer unit and to much hanging of 1 rcd ,earth leagage test was near the limit ,trip point ,so i rip out the board and fit rcbo instead ,had cross neutral too,you reminded me so much of my uncle ,and how he explain stuff,when on a job ,he say what customer wanted done ,and ask me to work it out ,parts,costs,time ,then he see if i made mistakes,also i had to draw circuit diagrams of how i would wire it up ,cable size,fuse,switch ect,use the nic eic book for ref ,and said iron out the mistakes at first step,his teaching methoud help me out over the years,and i help other sparks too,one had put in intermediate switches on a 2 way ,and got it wrong ,so i show him the draw a diagram way,calc runs,and he fixed it easy then , prefer 3 phase ,amour and cable trays to house bashing ,but work is work,my uncle retired now and designs wiring for hotels,warehouse ,building sites,still got my megger,old but works fine,r1 r2 zs tests ir 500v tests,wish i could of work with you ,would learn so much ,love the older sparks,they never seem stressed,just test and work out problem ,i check out the rest of your vids,refresh myself ,voltage drop over distance is another one i like ,long power cable to shed,and tt earthing ,data lines too,internet ,not done much cctv,but fitted sat dishes ,sky and polsat ,keep up the good work ,you are helping young and old sparks out ,earn good merit
Astute! Many thanks for this simplified explanation. Can do an OPL with the various segments of the explanations. Thanks a lot once again.
Glad it was helpful. Thanks for watching. Dave.
Another great informative video. Please make one for supplementary bonding as well
Will do Imran, its on the list now. Dave.
Great video, thank you for your work
My pleasure, and thank you for watching.
Great video - another video on supplementary EB would be useful as this is often misunderstood leading to unnecessary proliferation of clamps and short green and yellow wires. An explanation of what constitutes simultaneously accessible exposed conducive parts and exposed conducive parts would be great 👍
No probs Bagpuss, it is on the list to be done. Thanks for suggestions and for your support. Dave.
Brilliant stuff again dave 👍👍 an update dave, I’ve enrolled at local college and start in September level 2-3 2365 c&g 👍👍 I cant wait and I’ll probably keep going over your videos as they really are good learning 👌👌 as most have said thank you very much, keep them coming 🙌🏻🙌🏻
That's fantastic news. It really is a great trade to be in and its taken me all over the world. hard work but great experiences. You'll do well at college I'm sure because you WANT to learn. Keep watching the videos, even watch them twice or more. I always say that a dripping tap will fill a bucket. You've got about 200 days before college, just think how much extra you will know by then. learn as much as you can buddy and enjoy college, its worth it. I've enjoyed the last 45 years in this game.
take care, keep in touch. Dave.
@@learnelectrics4402 Love this saying " dripping tap will fill a bucket" .I remember I've really struggled when been doing Project for 2365 Level 3 with Adiabatic Formula, shame a haven't seen your video than... It looks like every college has its own preferences for a testing procedure for testing. We've only done a continuity test on earthing clump and copper pipe, I see now why you have to physically remove bonding .. Thank you Dave. I'm listening to your channel every day as I;'m going to work. Keep coming with new videos!👏🏻👏🏻
Great video as always Dave, thanks for sharing👏👍
Thanks Daddy B, much appreciated. Dave.
Dear sir the 16mm calculation not matching the calculation can recalculate and correct that please. Thank you for your video it fantastic and happy new year
Check your calculation and the order that you put the data into your calculator. Square root comes at the beginning of the written calculation but you need to do square root at the end.
Very educative as always. Thank you.
My pleasure Mwita. So glad that you found it useful and thanks for watching. Lots more to come. Dave.
What determines the max fault current that can flow. We calculated the max allowed for a disconnection 0.4 seconds that does not overheat the cable. Is it the prospective fault current ?
All the resistances in the circuit affect the current flowing. If its a water heater it will be 230 volts divided by the resistance of the cables to the heater plus Ze, in other words Zs for the heater circuit. Prospective Fault current is measured at the Consumer Unit as this is the worst case position. i.e 230 volts divided by Ze. Dave.
If it is difficult to access the bonding clamp, (e.g. hidden in the floor, but appears good visibly) could you also reverse the test by disconnecting all the earthing conductors at the consumer unit bus bar and test the individual earthing cables from the end at the CU to the other end e.g. by a bathroom radiator?
Why not disconnect just the circuit under test at the CU and use a wander lead to test to the earth clamp. That will also eliminate parallel paths.
@@learnelectrics4402 I think that was what I was trying to say, same as the video just from the other end? I notice in new builds they often have the earth bonding on show in bathrooms by the radiators but this is quite unsightly. Is it OK to place this below floor level as long as tests ok? I'm theory you can service by cutting a hole in the ceiling from below.
dear sir the you calculation 16mm cps its not matching with my calculation can you recalculate or may be some errors I have try your formula but not same answer so I will be happy if explain thank you very nice explain step by step it very helpful . thank you
Check your calculation and the order that you put the data into your calculator. Square root comes at the beginning of the written calculation but you need to do square root at the end.
Hi sir it not work any other calculations please
Hi. can you tell me please, where can i find answer for this question on amedment2 WR book?
an earth busber connected to a 250A per phase supply, must not be thans
1. 50mm2
2.16mm2
3. 10mm2
4. whatever the guidance 54.8 explain
i know its in chaper 54 but i cant find answer. can you give me more information or i have to use calculation form?
Main earth terminals and earth bars will be found in 542.4 of the brown book, amendment 2. Good luck. Thanks for watching. Dave.
Does a oil boiler incoming pipe need bonded if it comes into outhouse with copper pipe but insulated with white coating at point of entry?
If it does need bonding what size of cable.
It would normally be bonded Ciaran as the copper pipework is probably earthy at some point. Dave.
Hi Dave
Superb videos as alway
Can you do a video as to why we have the bonding conductors 16mm and 10mm.
Why are they that size?
What a great idea Andrew. Its on the list to be done. Thanks for watching. Dave.
excellent video thank you again
Thanks Azizur, thanks for your support, appreciated. Dave.
Thanks Dave
Thank you David. Thanks for supporting the channel, it means a lot. Dave.
Can I ask a question please about size of earth please. How do you choose correct size earth for fly lead from banjo on an swa where armourings are the cpc?? Many thanks
The fly lead should be the same size as the conductors or a minimum size of 2.5mm inside the housing or 4mm if connected outside the distribution board or housing. Hope this helps. Dave.
@LEARN ELECTRICS Thanks Dave. Everytime I've seen a fly lead from swa it's on inside of DB from banjo and thought people just used 6mm as standard regardless of size of swa. He certainly asking what size should be
Thanks for the video. My maths isn't what it used to be but I agree with the 6mm answer (1090 amps) but get different answers for 10mm (1818 amps) and 16mm (2909amps). Am I missing something?
I got the same numbers as you.i think the table is wrong or we both are 🧐
Thanks Grumpy G. You are correct as is Terence. I think that was the calculator that I actually threw in the bin yesterday, I suspected it was faulty and bought a new one today. I know the story of blaming your tools but that's the truth on this occasion.
Anyway, so glad you actually tried the calculation. I'll correct it. Dave.
Thanks Terence, yes, you and Grumpy G are right. That calculator is now in the bin - seriously - it kept failing on me. New calculator bought today and I agree with your results. Good practice for you, and thanks for the heads up. Dave.
great video!!!
Glad you liked it and thanks for watching. Dave.
hi can you please do lesson about emergency light with emergency switch
thank you
Thanks for watching Mohammed. I've put your request on the list. Dave.