Earth fault loop impedance explained

[@sparkymarky008]

Alan, I'm currently studying the 17th edition and got to earth loop impedance. You have explained this in such a simple understanding way. Thank you very much.

[@squakkers]

If only the IEE produced material as easy to understand as Alan. As someone currently studying to be a domestic electrician I found this short video more informative than volumes of study books. Thanks for the time, effort and clarity.

[@rowensimpson4123]

that was a really good explanation, something my electrical safety tutor couldn't manage. Thanks

[@11dimmick11]

brilliant, didn't quite understand what i was doing but this has made it alot clearer, cheers.

[@sohpar4755]

Dear Mr Hobbs, Very good explaination special the blackboard one, look forward to seeing some more video from you about ZS, Insulation testing, RCD Testin and other tests. Thank you, Sol.

[@ElectricaltestingCoUk1966]

Hi Stefenski, without seeing the installation its difficult to be sure but you may have a TT Installation; this would have an 'earth' provided at the installation usually by way of an earth rod and make no use of the Electricity Suppliers earthing facility (or may not be provided with one). This is typical in rural locations and more info can be found if you search for 'earthing system wiki'

[@SkillBuilder]

Good demonstration, very clear. Thank you. Crap camera though

[@fmdtech]

Hi Alan, was wondering on the connection of the meter you used, I understand the connections you make in the video ,but I can see another black lead with a clip on it, is this going to the neutral bar ?

[@user-vb5fs1sf2y]

Nice clear well presented video, thanks.

[@roddyrodrodrod]

Was this recorded in the 1970s? Good explanation though.

[@purohit3000]

Nice explanation,thanks for sharing

[@prabhakarann7541]

Excellent explanation.

[@yanaayzen4951]

fantastic exolaination. thanks

[@peecj]

Is it important to remind people not to touch the any earthy parts during testing? I noticed you are wearing a metalic wrist watch in the video, and have it fairly close to the metalic casing of the DB.

[@mtm8988]

very well explained appreciate it!

[@Titi101088]

Great explanation! Thanks!

[@Stuartiamyourhorse]

Thanks buddy. Ze simplified.

[@markkennard861]

Is the connection of the meter probe to the phase conductor on the main switch Hi Z itself ? By just holding the probe on the live screw wouldn't this introduce a Hi Z connection thus cause a higher reading than actual. All other system connections are large cables and under lugs with nuts and bolts. I guess the meter calculates the impedance of the probes and leads and brings them into the equation ? If the main earth conductor was just held onto the main earth in the same way would this test show up a this bad Hi Z connection for example ? Cheers Mark.

[@ElectricaltestingCoUk1966]

Hi Mark, if I understand your question any connection like this will introduce an impedance however on a low voltage installation, with a good probe contact it is negligible. For a high voltage system the contact resistance would be critical.

[@3beltwesty]

The impedance is calculated by the Gizmo meter. The Gizmo unit measures the voltage, then adds a small load current and remeasures the voltage and thus the "voltage drop" is known for the test current. Example: One might have 237.78 volts with no load and 237.57 volts with a test current of 1/2 amp. Thus one dropped .21 volts with 0.5 amps V=IR thus R=V/I = .21/.5= 0.42 ohms The test load is only applied over a short time. The test meter measures the voltage with and without a test current, then figures the impedance. Because the test current is going through the test leads then yes the gizmo uses the leads in the calculation; or might use two internal wires on each lead so the voltage is remotely measured right at the probe tips.

[@AnaS-it3jj]

thanks Alan

[@chenwei8064]

thank you

[@ElectricaltestingCoUk1966]

Hi, thanks for your comment. The Neutral is returning to the star point in the video, I appreciate that it is draw slightly below the centre of the 'star' but this is still the star point and is also connected to earth; this is a correct drawing.

[@uddaside]

Had to draw this in 2391 exam

[@CAIN8K4]

17th Edition is an open book Exam YOU CANNOT FAIL, even i passed it LOL