Electrical Capstone Practical Exam Fault Finding -Earth Continuity
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- เผยแพร่เมื่อ 13 ก.ค. 2024
- Tutorial and tips for fault finding earth continuity.
Main Earth Resistance -Less than 0.50ohms
Equipotential Bonding -Less than 0.50ohms
Protective Earthing Maximum Resistance -Refer to Resistance values in Table 3.2 ASNZ 3017
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Thanks a lot for your help, I just passed my capstone, and your videos helped me a lot 💡🎉🎉🎉
Well done you're a real cobber to all those stumping up to the capstone exam 👍
4th year sitting capstone in May - thank god for your videos! Only experience I have had with a switchboard/mandatory testing is at tradeschool (and they don’t teach you much because they expect you to know it all already!!! Shame not all of us do!!!!)
Thank you so much for your videos. I’ll be watching them on repeat for the next 2 months! Thank you thank you!!!!
This is why I created the videos. I was just really lucky to have some good teachers at my TAFE who did the precapstone tutorials who explained it in a commonsense way.
Sitting capstone next week, your vids have been amazing, thank you!!!
How did you go?
Nice work. I like what you have done.
perfect, very good demonstration thank you
yes. wish she had more content. its very useful
Sitting my Capstone soon, your videos are so helpful! Thank you!!
Absolute champion, thank you so much
Unreal that I have to go to TH-cam to find resources like this, great work though! Apprentice in WA, sit the Capstone next week.
How did you go?
@@theea3466 Passed! Your vids really helped!
@@Jdawg6000 Well done!!! Your hard work has paid off.
Hey, I’m a second year in WA too! Did you make your own capstone board up? I’m trying to figure out all parts I need to give me best shot at practical stuff!
@@carawithnell7723 it may change in two years time but from memory, 63A Main Switch, 2x C10 CBs, 2x C15 CBs, C20 CB, C25 CB, 2 RCDs, a din rail switchboard, 4x double GPOs, 4 lighting points, 2 isolators, main earth stake, 2 2 gang switches, pretty similar to the set up she has in vid but we do things a little differently in WA. I didn’t make one myself but it’s a great idea to help.
Doing my capstone at the moment , helped a lot thanks 🙏
How did you go?
I’m finding this really helpful
Super helpful thank you !!
You are a hero, thanks for helping so many people.
I don't consider myself a hero but I'm grateful for the positive feedback. Is there any particular subject areas you'd like more videos on?
@@theea3466 maybe safe isolation and DOL
Thank you so much absolute legend !
This is great. Preparing for my Capstone prac later in the year ...
Good luck bud. If there is any topics you need help with let me know.
I will thank you. Great to see other female sparkies out there smashing it. I’m a 4th year at the moment.
You'd be just out of your time now I imagine Nikki, love the video!
Got my capstone on the 30th, never had any trouble with the theory but have always struggled with the practical side of things, thanks for this
Congrats on passing capstone. So glad you got through it and yip that's why I made the videos.
Thanks a lot of these videos. A lot of these points seem to have been neglected from my course.
Something I did notice is that earth continuity cannot be done with a normal multimeter. Not sure if they allow this in the capstone.
AS/NZS 3017 says the test equipment must comply with AS 61010.1 and IEC 61557.
In IEC 61557-4 Resistance of earth connection and equipotential bonding states:
4.2 open circuit voltage shall not exceed 24 V and shall not be less than 4V
4.3 Measuring current within the minimum measuring range according to 4.5 shall not be less than 0.2A
4.5 Measuring range within the operating uncertainty in accordance with 6.2 is maintained, shall include the values between 0.2 and 2 Ohms
normal mustimeter do not measure at 200mA and are not accurate for these low resistance values. Hence why it is only giving you one decimal place. Just something to keep in mind as it caught me out too.
AS/NZS 3017 Page 8 says test equipment should comply with requirements of IEC 61557 and Page 6 states 3017 refers to IEC 61557 Parts 3 & 5.
4.3 is saying your testing range needs to be larger than 0.2ohms.
Ideally you'd use analogue ohmmeter as figures show in AS/NZS3017
My multimeter reads more than 1 decimal point as I show in the video and multimeyer ranges do go below 200mA.
Different multimeters have different ranges, accuracy and resolution..
❤nice, thanks 😊 best of luck with your exams 😊
😎😁💪🍻🍕
Good luck to all the lads and ladies studying hard. Should all be proud of yourself.
you are champion
Nice
👏👷♀️👍
I miss being an apprentice hahah fun day.
Thanks for your great videos they help. Do you still have your board?
Yes and No.
I had to pinch parts for jobs I needed to do.
Hi Could you give me a clue as to how you test the earth continuity
on a underground cable connecting the MSB and a sub-board. Thank you
Depends on why your doing it?
Keep in mind I'm not a teacher but will explain it the best I know how.
If you know that N is sound and not intermixed you can attach the Neutral to earth at either the MSB or sub board. Then go to the other board that's not attached remove earth and Neutral from bars and test resistance if the resistance of both cables are lower than the maximum resistance according to table for cable size and CB size you know it complies.
If it is strict testing like in capstone. You'd use a trailing lead or in fact any cable you have that is long enough to reach your MSB and Sub board.
Step 1 Test the resistance of your trailing lead or cable. Write the ohms result down on paper or cardboard or enter into your phone.
Step 2 attach lead or cable to the underground earth cable at one location either at at MSB or Sub board.
Ask yourself what am I attaching this lead to? Have I attached the earth cable only for this cable under ground?
Then walk the trailing lead to the other board. Remove the earth cable for that cable underground out of the earth bar.
Test between Earth of the underground cable and trailing lead or connected wire in cable.
Write the result ohms down.
Then subtract the trailing lead or cable reading that you wrote down before.
This will leave you with your restistance reading for just the underground cable.
Does this help?
Please don't be afraid to ask your teacher. Chances are if you don't know half the class won't.
@@theea3466 Thanks heaps great reply
Why to check the continuity for main earth and equipotencial bond you remove from the earth bar and to check the GPO’s and lights you didn’t remove?
Very good videos but I’ve got confused..
Hi, awesome video. Just in regards to the table reference you made (3.2) which rule book is this in? As table 3.2 is limiting temps for insulated cables in As3000.
Thanks !
It is the Maximum values of Resistance for Earth Fault Loop. Table 3.2 is from AS/NZ 3017:2007 Electrical installations -Verification guidelines. Page 40.
However this is exactly the same as Table 8.2 in AS/NZ3000:2018 on Page 428.
Awesome, thankyou!
Hi. Thank you. In reality the socket outlet is for example 10 meters far from the switchboard, how should I test the continuity ? Using a voltmeter with 10 meters cable ?
Great question. So what you'd do is use a trailing lead. You can use any cable that will be long enough to reach 10m. Use a multimeter or a meggar to measure resistance of just your trailing lead cable. (Write the ohms down on a bit of cardboard or paper whatever you have available ). Then attach one end of trailing lead or cable to your earth bar and run cable through house to your PowerPoint 10m away. Then you'll test resistance between the tip of the trailing lead or cable to the earth on the PowerPoint. When you have your resistance measure in ohms you just have to -(minus) the cable resistance to get the resistance of the circuit.
For example
Measure:
Trailing lead ....reads 2.60 ohms
Trailing + circuit.....reads 3.10 ohms
Calculate:
Circuit= (trailing lead+circuit) -trailing lead.
3.10 ohms-2.60 ohms =0.50 ohms
Hope this helps bud.
@@theea3466 What if we are unable to use a trailing lead due to people or it is not practical? For example, a factory setting with people driving forklifts or pushing trolleys around?
@@doctordoomsnipes
Keep in mind usually this test is done before energerzing. Could be tested after work hours. Another option is to remove unenergized neutral from board and join it to the earth wire in the circuit your testing. Measure the resistance at the other end. If the reading of both cables together are lower than max level your sweet as.
1st year trying to understand 🤯
Is there any good resources in wiring a domestic board?
If there is I haven't seen it yet.
I was going to make a video on Main Switchboards so I'll try to get that happening. Things are a little chaotic with the flooding at the moment.
Don’t you have to check that each protective earth conductor is not switched?
So when you do Earth Continuity you are only testing the earth conductor at the earth points.
BUT.... if the earth wire was placed in the switching wire terminal you will not get a continuity reading at the earth point. The tester will read OL.
So for the test you will write OL no continuity and you'll later discover the error when you do the polarity test.
There's no harm in checking though. Like if I came across a switch and I have no continuity at earth my first reaction is to test the A and N. If you do it during the capstone, just make note of it on your records and continue with the testing steps. Just make sure you still do the polarity check on the switch when your up to Polarity testing to confirm just 2 wires connected wrong or all three and check resistance readings in case extra wires are added etc.
There is a systemic system for how you test.
Step 1) Earth Continuity
Step 2) Insulation Resistance
Step 3) Correct connections
Step 4) Polarity
Step 5) Fault Loop Impedance
Step 6) RCD Operation
Hope this helps :)
Are your circuit has a ring circuit?😊
Be that ring circuit in circuit are? 😎😁
You removed earth from the hot water unit but not from the equipotential bonding. Shouldn’t you take it off the pipe as well?
Great Question.
I have no pipe on here just earth stake.
What is equipotential bonding?
What is it attached too?
In this case it's the metal water pipe and its attached to my Hot Water System.
Your water pipe may have a parallel path so that's why earth comes off the HWS.
Is everything reversed because you are in the Southern hemisphere?
Earth continuity less than 1ohm? Main earth and equipotential have to be 0.5 ohms or less
Yes at 1.47 I say all the resistances you'll measure are under 1 ohm referring to getting your tester tested properly it wasn't meant to be specific to Main Earth or equipotential.and includes all test readings. Technically final sub circuits can go up as high as 3 or 4 ohms and be a pass according to AS/NZS 3017:2007 Table 3.2.
Main Earth and equipotentialbonding does need to be least than 0.50 ohms.
Watch from 4:00. All final circuit resistance readings need to comply with earthing Table 3.2 in AS/NZ3017. The limit of ohms is actually dependant on the size of the cable, the CB size and type. So some cable with a reading of 0.4 ohms will actually be a fail. Some with a reading of 0.8ohms is actually a pass. Get familiar with the table you will need this table during your exam.
@@theea3466 thanks for replying. I was being a smartarse. I think you are doing a fantastic job putting yourself out there as an apprentice and doing a testing presentation. Shame some tradies weren’t as dedicated to the trade like you.
Just a pointer on earth resistance there is a sub circuit where the earth resistance reading is above 1 ohm. Maybe a reference to Table 8.2 (from memory) to check what the maximum resistance allowed for the circuit under test.
Keep up the brilliant work.
Cheers
Steve
@@stevechadwick180
Table 3.2 goes up to 6 ohms in 1mm cable but got to keep in mind limits and rules in AS 3000 in regards to cable size for power and lights.
If the thinking is that the final sub circuits just always less than 0.50 ohms apprentices will struggle to pass.
@@theea3466 When we delve in and only good tradies will delve in and start researching and asking questions it gets deeper. I noted you said you need to ascertain if the installation is new or old and this will make a difference to the insulation readings. 50Mohms opposed to 1Mohm. This would also need to be cross reference with the SIR (service and Installation rules) unless working in WA or Qlds where they have there own name for this document where mains are required. To have a reading of no less than 50Mohms ( that’s from the VIC SIR and from memory). Also another one for old players the same question asked when performing the main earth and equipotential resistance test prior to the AS/NZS3000:2007 the reading would pass if it was 2ohms or less. So doing a test on an old installation 2ohms may be acceptable.
@@stevechadwick180
Thanks Steve.
I do mention the difference between acceptable levels between new and old installations and say to ask your exam officer if they don't tell you its new or old. I made so many videos I'm sure its in the first one. I retook a few videos and I didn't edit so im hoping its there and not in a deleted video.