Electrical Capstone Practical Exam Fault Finding -Insulation Resistance 

Wishing you the best of luck. Let us know how you went.

Pat, for two and three way switching you need to test on and off for each switch. Two-way. Test circuit with both switches in current position. Flick switch 1 Test. Flick switch 2 Test. If it helps to draw a picture of what you are testing. Remember your testing each piece of wire in the circuit between accessories. ------/=======/------- Three way Exactly the same Test. Flick switch 1 Test Flick switch 2 Test Flick switch 3 Test. ------/======/======/------

Link: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-i8bavUrrBx0.htmlsi=7QCsN_h388ue7xvh

For Complete Installation Bridge A and N at supply. Or Bridge Line and Load if meter. All CBs and RCDs On Disconnect MEN/HWS/Oven elements. Test Ebar to Nbar

At 58seconds I say load side of supply to L1 L2 and L3. Remember also Main Switch is turned on but all other CB and RCDs are off so it's not testing any sub circuits.

It makes sense now! in our pract we don't have a sun main to check. Only consumer mains and final sub circuits:) thank you

@@warrenkelly4561 All good. Just remember lots of places do run submains. As long as you get bigger picture.

Yes. When you test for complete installation your testing the entire system. Mains + Submains +Final subcircuits. If you test at the mains with everything connected your testing the entire installation. If this passes everything is fine. For the capstone you need to test each section to show you know how. Remember IR test is checking for any insulation leakage under pressure. The rules state all live conductors needed to be tested with earth. Neutral is considered a live conductor.

Rewatch @4mins Submain is not on a RCD it's a CB so you need to remove connected N from N bar. Need to test N and E to Active E to A and N to A. The Neutral was removed at the Neutral bar. Usually your load side comes out from the top. This is because dust and bugs can accumulate on top so if you have a fire it's best it happens on the more protected side.

50secs -Main Switch 4mins -Submain. This is a CB that runs cable to another location like a shed or outdoor area There is no service fuse on here. A service fuse runs along service cable (Incoming Supply) My service cable is the extension lead cable that I had removed at the very beginning of this test.

Check out the installation diagrams on this website. It may help. www.electricaltechnology.org/2021/03/wiring-consumer-unit-distribution-board-rcd.html

Great question. Yes there's other requirements. This video is just for Insulation Resistance only. I have other videos on the mandatory testing you are describing; polarity, earth continuity and earth faults. There is a process for testing and it follows a particular order. This can be found in AS/NZ 3000:2018 clause 8.3.3 Check out my other videos.

I agree with that guy

NEVER TEST ACTIVE - NEUTRAL!!! You can blow up sensitive equipment at 500V with an IRT test.

@@maxwilson6964 not sure the caps were necessary but ok. So how do we verify that the insulation is good between them? Ps, my main trade is railway signalling so I'm fully aware of the sensitive equipment issue, we disconnect the cable on the railway to carry out this test. Essential to ensure no false signals can carry between cores which could turn a signal Green that was supposed to be red. Trains crash if that happens. We also test at 1000v to ensure we stress the cable far beyond what its ever expected to carry. Rigorous testing for highly safety critical equipment

@@paterson00 at the end of the day as electricians we are provided with standards to follow, As3000 section 8 verification outlines the requirements of an IRT. This video represents a guide (from an apprentice) on IRT. In my experience each individual will come to their own version of testing, some will float some will sink. Its up to the individual conducting the testing to determine whether or not they will certify the installation or not.

I passed my certificate of proficiency interview yesterday because of these videos i can get my NSW licence now

No I don't sorry bud. When you sign up for an apprenticeship a teacher will go over these practice tests with you.

Great Question James. This test has to be done before power is applied. Check Clause 8.3.1 AS/NZ3000:2018 This test ensures that the integrity of the insulation is maintained and no live conductors are 'leaking' to earth. The fuses would be not installed until all mandatory tests have been completed and the installation is proven safe to power up. The tester is applying an intermittent 500 Volts to the dead circuit But you need to test each wire and accessory that's why we switch 2-way Light Switches etc. Also important to switch Main Switch On/Off to separate the final sub-circuit, sub-mains and Consumer mains as Clause 8.3.6.1 states they need to be tested separately.

It's a new installation. You have run the cable but it's not connected at Connection Point or Point of Attachment. You have to check the entire installation before connection. :)

Thank you so much that makes sense now @@theea3466

These test are performed to check system integrity before any supply power is connected. So no you don't need rubber insulated gloves. E.g You have just wired a new installation on a new house, your checking system before supply is connected.

Firstly, there is no scenario in which wearing PPE is wrong. If you want to make it a habit to wear gloves, go for it. Also, you should note that when running an insulation resistance test, your tester is pushing 500V of DC current through the installation. You should definitely be careful when conducting this test.

Great question. Yes! Page 17 AS/NZS 3017:2007 Test Sequence 4= Disconnect the supply Neutral from the Neutral bar. For the exam you are required to test sections of the install so yes Neutral needs to be removed from the Neutral bar. You need to bridge Active and Neutral to test a complete installation.

Yes you do t n c s systems you would get a short on the reading as the neutral and earth are joined at the meter position

It's in the NSW SIR and it's specifically states this for brand new installations that have brand new service conductors. Brand new wiring shouldn't have any resistance other than the wire itself. What increases resistance? Moisture, leakage..etc. SIR. 1.12.3.1 Minimum Insulation Resistance. 'The insulation resistance between conductors and between conductors and earth of new services shall not be less than 50 megohms when tested using a 500V DC insulation resistance tester.'

I do believe this is for the service side (level 2 work) as 1.12 ‘Provision for services and service equipment’

hey mate, I 100% agree with you ! I have my capstone practical exam in two days and watching this lady do a insulation resistance test is giving me anxiety, my prac involves an IR test on a WHOLE INSTALLATION. can you please reach out to me and give me a helping hand or even some advice !

Sean Appreciate your reply. I do these videos start to finish with no edits so I failed to mention this isn't full installations test. The video shows how to test each installation section separately. Consumer Mains only Submains only Final Subcircuits only I apologize if I didn't explain the clearly at the beginning of the video. The board is dead. This is a dead test. 2:22 Clearly state existing homes have to be greater than 1Mohm. Only new installations have to have a reading greater than 50M ohms. I can't comment on UK Rules. I'm not familiar with them. In the final Subcircuit section where you'd expect to find your loads connected I say @8:05 resistive loads out or check requirements for load. E.G A heating element attached has to have a reading greater than 0.01M ohms. If in doubt remove element testing just circuit cable. @8:24 7 I comment how electronic sensitive equipment needs to be disconnected or have insulation resistance test voltage reduced to 250V. The simmersat is a great realistic example of what to expect. George, Yes my apologies this is not complete installation testing. Complete installations are great but knowing how to test each installation section can help locate faults quicker. Please ask your Teacher or employer to go through IR with you if your still unsure. My videos are just a guide and I apologize you now feel confused and anxious. I hope your capstone went okay.

@@theea3466 hey I’m doing my capstone Wednesday and on the practice sheet it had earth continuity test and earth fault loop (Zint) what is Zint am I just testing resistance between earth and active to find Zint?

I have a video on Earth Fault Loop impedance. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-l4JDSfJZ9P0.html With the readings refer to table 3.2 in AS2017 and Table 8.2 in AS3000 AS3000 is to 1 decimal place. AS3017 is to 2 decimal places. It's typically same table information but you'll notice it's not exactly the same and some figures are different. When in doubt always use the safer more protective figure. If you teacher states to use one table as the reference follow teachers advice and instruction. Z=impedance Int= internal Earth fault loop consists of 2 parts Internal and External Conductors upstream of the reference is External. Conductors downstream of reference is the internal. AS3017 Clause 3.6.2 (e) and (f) Figure 3.21 on page 37. Using a highlighter highlight impedance paths: Zab Zbc Zfg Zgh Zha These are all upstream of the their reference point this is the Zext. The protective device is the reference point. Grab another highlighter colour. Highlight path Zcd Zde Zef This is the Zint The Internal path of fault. Then check AS3000 B4. 4 Page 447 and P448 This is the same diagram and details but it references B5. B5.2.1 has a determination of Zint and explains more clearly the difference between Zext and Zint. States Zext includes transformer and supply cable. In Notes it states Consumer mains also part of Zext. It says Zint can be determined where cable length and Cross Sectional area CSA is known. Zint=Zcd +Zef Zcd= Impedance of Active conductors. Zef= Impedance of Protective Earth cable. My rusty notes Fault Current is known as earth fault loop. Test applied to: Circuits not RCD protected Socket outlets >20A Fixed Stationary Equipment >18kg Submains Good luck. Hope this helps

@@theea3466 I passed!!!! Thank you so much!!! Honestly couldn’t have done it without you