Prospective Fault current test

[@moeketsimothlabane8278]

I gained more knowledge about these tests thank u very much

[@jamiebryan8740]

Does GS38 not apply to this test?

[@djc-ln2pq]

Jamie Bryan it would appear not...

[@3beltwesty]

Steve, PEFC 370 amps (hot line to earth ground ) and PFC 350 amps (hot line to neutral ) are about the same value. My USA guess is because the earth and neutral wire are tied together "upstream" of your breaker box, and use about the same size wire too. Is the far green E earth wire the same wire size as the L brown line and N blue neutral? The green looks smaller but is farther away from the cameras thus probably just the prospective. Nice video, here in the USA tests like this are not done as much. But on old building upgrades or unknown installs sometimes one tests at the sockets / receptacles / motors to find poor connections and poor degraded switches. By testing it might just be without a fancy device for fault testing, ie all manual: ie have a digital meter to measure our 120 or 240 volts and a switchable load like dumb incandescent bulbs to add a load of say an amp. ie 240.6 volts with no load and 240.1 volts with 1 amp has a 0.5 volt drop for that 1 amp or a 0.5 ohm calculated impedance. Thus the short circuit current is 240.2/0.5 or about 480 amps.

[@afcbarron]

are you not supposed to disconnect the earth from the MET and connect to directly to the main earth when measuring the PEFC?

[@tspirit99]

Nope, that's for the Ze test... to verify there is a physical connection... PEFC and PSCC comes after. PEFC and PSCC tests cannot verify ADS(automatic disconnection of supply) as there is no protective devices from the Ze point.

[@ningis21]

I am of the opinion that there may be a misunderstanding of what Steve is actually testing, ...Isn't this test supposed to check that the protective device you have selected to install in your consumer unit, can handle the PFC without total distruction.... In this instance I think that is what Steve is doing and isn't this why this test is carried out?..So I wonder what made people think otherwise, after all the main suppliers fuse is only rated at 60/80/100 Amps (single phase in the UK)...but they have KA amp breaking, and this has already been explained by another viewer below....even if the Maths were wrong..(don't you mean 4.8KA Amp not 48KA...using his/her numbers). The tripping time under fault conditions is a different matter, as I am sure you are all aware....and perhaps, referring to. In addition to the above...if anyone wishes to view the many videos on KZbin they will see that the test was carried out correctly...and that every other video shows that the test is carried out to assess the capability of the fuse/MCB etc... is actually capable of carring the load. There is however, one more issue..............Why did...TransEuroEngineering... not even bother to reply and explain this to anyone???? and therein..lies a problem..... So....I agree (for different reasons) remove the videos...if the provider cannot be bothered to provided an explanation...then why should we???

[@Treefrogging]

I know we go on about safety a lot, but as noted above the leads are not GS38 compliant. Measuring pfc and pssc with the probe tips well exposed is pretty bad. Fused test lead would aid operator safety also . The clip on the CPC terminal is not fully mated. I hate pointing out the basics , but flashovers do happen and usually because of carelessness. I observed it happening when I was trainee and it was scary. Please highlight the safety points before any more videos go online, otherwise all the guys trying to get through 2394/95 will fail at the first hurdle.

[@Prawnchowmein]

The breaking capacity of the main fuse will need to be lower than the PFC.

[@kilovatio5557]

+Prawnchowmein Exactly! How is it that having CBs of 6,000 A breaking capacity will protect a circuit with both earth fault and short circuit PSFC and PSCC of 370 A and 350A, respectively?! The whole purpose of a protective devise is to trip before a circuit or any relevant point of the electrical installation reaches its maxumum PSCC or PFC!!! If that installation has in place those protective devises then surely the PFC and the PSCC are higher than 6,000 A. I seriously suggest this video should be withdrawn. It represents a hazard in itself! It will certainly confuse the inexperienced student.

[@kilovatio5557]

+Kilovatio I can see the trainer was totally confused. He said that in that electrical installation the circuits had a 'very high impedance'. This is nonsense. Conductors should have a negligible impedance so that, in the event of a fault, the current can flow quickly without 'friction' along the way and then make the protective devise to trip. But, in this video, he was not measuring the earth fault loop impedance or the short circuit loop impedance. He was supposed to measure the prospective fault and short circuit currents and compare these values with the RATED current of the protective devise so that, in the event of a fault to earth or short circuit (fault between line conductors) the devise brakes before the circuit reaches its PFC or PSCC. Yes, please remove this video.

[@ivandrago8299]

When you take PFC and PSC readings you record the higher of both readings which is called IPF. Most test meters only record up to 20KA but using Ohms law you can calculate the actual IPF. This will nearly always be 48KA Maximum as you will use measured Line to Earth voltage of 240V with a resistance of 0.01ohms ZE and using the rule of thumb method for 3 phase you will double it. So V=IR (x1000 for KA and X2 for 3 phase) 240V =I X 0.01OHMS So reverting the formula V=IR to find I is I=V/R which is I=240VX0.01 x1000 x2 So most I have ever recorded is 48KA in 10 years of working as an Electrical Inspector. Yes you can get some Line voltage readings that might be higher or lower than 240v which will affect your result. It should be noted that the Regs also allows an IPF reading to be higher than the breaking capacity of the MCB at that board if the DB is supplied with a sub-mains circuit which an overcurrent protective device that has a higher breaking capacity than the measured IPF. Example; You could measure 16KA at a DB that has MCBs fitted with 10KA but if the cable supplying the DB has a switch-ed fuse with 120KA breaking capacity there is no fault to record. This is quite a common occurrence.

[@jasonalexander7434]

@@kilovatio5557 Your an idiot. This test isn't to check if the breakers will trip, it is to see if they can handle the maximum possible fault current that may occur without destruction, which may lead to the terminals welding together and continuing to allow current through the device.

[@AnonymousPacifist]

Very noble!