Why not use multicore cables for point to point in robust ducts to equipment housing etc. allowing for some redundancy ( spare cores should you loose a circuit and have to divert a function) running single core in that type of duct seems bonkers…..not thought out very well but this is indicative of new technology and its applications …..
DC cables coming from PV do not get power from "both ends". The issue is PV is DC, and thus has no zero-crossing like AC does, so the arcs can get enormous! The inductance of the PV array can generate a huge arc. (I am an EE)
@@jamieblatantsparky The inverter side does not put out power, and in fact; most inverters have arc-fault detection which will dump the load to reduce the change of fire for a loose connection that is arcing.
@@Ingineerixyour failing to recognize previous technology, every thing your saying applies to modern systems but it was not always like that , this is a 15-20 years old solar farm working on much more basic DC technology
I doubt the inverter would keep back feeding like that, they automatically do insulation tests, can’t see that passing with copper sitting in water or shorting. Yeah the other end will burn all the ways back to the panels eventually.
Nice fault mate. I done a lot of work on external security systems and seen that effect with voltages from 5Vdc to 24Vdv at milli amps of current. It’s the magic of DC that basically magics the metal away when a current path is established due to water. Electrolysis moves ions from the positive to the negative. Natural salts from the groundwater will improve its conductivity no end and once the reaction starts it will keep going till there is nothing left. It doesn’t happen on AC as the changing polarity puts the ions back!! Automotive wiring suffers similar failures due to water ingress. All the best.
OK.. at mA. That was instantaneous arc.. plasma vaporising the copper, tin, plastic, maybe water. Big volts and high current fault there. One flash and then ash.
@@BTW...Aye, for sure it would have been quite a flash. The higher voltages and current will certainly do more damage. My point was that even a low voltage and current the DC effects are superb compared to AC. Cheers
Hi Jamie, I agree 100%, like you I am amazed how thick a large portion of the so called general public are, just take a look at how many thick sods fall for "I'm calling you from your bank etc." by someone with a strong Indian accent, do they think all the people in the bank are Indian? I give in matey, I challenge them to call me and I will teach them some "Jamie" phrases, my misses normally answers the phone, she knows how much they piss me off. Rant over. Regards from the old sod etc.
@@freddiewithers9617If all those positives or negatives melt together I’m not sure you get a better outcome, could end up with currents well beyond what switchgear is designed for?
@@edc1569 The arc fault condition which caused the cables melting together would be much less likely since the different polarity cables would be in separate ducts. This fault would be extremely unlikely if the different polarity cables were spatially separated.
No rodent will get up such a small space to chew cables. The 'rat' that nibbled the insulation has 2 legs... the butcher that pulled them into the conduit. That shitty conduit is NOT suitable for direct in ground installation.... simple as that. You are dealing with DC at higher than typical voltages. Once an arc propagates it does not self extinguish like an AC arc fault. I've seen a PV DC output cable maintain an arc easily across a 300mm air gap, once started. Try yourself if game... spark the cables and draw apart on a sunny day. You find water in poorly installed conduits. The 'green' you see could have come from the burning of the PVC insulation and conduit. Combustion products of the plastic create highly corrosive compounds. Do it right - Do it once. Single insulated wire (we call it 'building wire' despite the fact it isn't appropriate for building installation) in a pathetic thin wall conduit, more apt for a bloody LV car wiring loom, buried in the ground or subject to mechanical damage is NOT an approved method of installation by any standard. I bet the bodgy bastards that did that didn't even use correct conduit glands, met IP ratings, saddled correctly, protected against abrasion or considered appropriate depth when they buried it in ground. I bet they didn't even derate the cables correctly. It's a waste of good materials doing a shitty sub-standard job like that. I'd consider failing and condemning the installation, and then rip-out and start again using the correct materials to be compliant.
Did the cables have the correct insulation rating - voltage, temperature? Were they even double insulated? Normal bog standard house wiring cables are NOT rated for PV array voltages. Were the cables derated for enclosed installation method, or correctly installed to code? Probably not. Did the installers actually use DC rated overload trip devices... or even DC rated switchgear? Better check... idiots do stupid shit. Was the installer some DIY dickhead with no qualifications to do that category of work, and know how to test prior to connection? How is this allowed in a supposedly advanced society when the equipment can easily kill or burn down a house/s next door?
You know the other fault that can occur when an unqualified idiot swaps out an obviously burned 3p motor with a spare that kinda fits? Assume they get the Star or Delta connection right... perhaps. Assume they get the direction of rotation right and know how to correct that... perhaps. The idiot installs a 2 pole motor when a 4 or 6 pole is needed, and wonder why the machine doesn't work correctly. This shit happens.
LOL. You call 500V insulation test "spicy" voltage. What do you call 2.5kV or 220kV testing? i.e. 10x working voltage potential. In the field, you may as well bridge all windings and in a single test measure all to Earth in one move. In practice, that will indicate a fault and the motor is taken out of service for rewind.
Terrifying, considering the PV solar cables i have in copex running through people's houses! I would like to see a 5 core SWA with DC colours and cpc used as standard. The cpc is now essential as the next big thing will be the breakdown of insulation in the panels themselves. The simplest solution is to earth the PV subframe and do an insulation resistance test from earth to negative and again to positive, which the fluke does not mind on 500 volts.
Oh FFS... copex is NOT insulation rated for PV installation. That shit copex doesn't even have an insulated or multi-strand Earth conductor. Output voltages from PV arrays can far exceed 500V DC. Furthermore, 500V insulation resistance test should be at 1kV. And what sort of idiot doesn't Earth PV frames? SWA? There goes your current rating. Do you like paying for cable with a larger than needed gauge/cross sectional area, derated so much because it can't dissipate heat as well as a correctly installed correctly rated cable? SWA has limited applications to protect against mechanical damage. It's heavy and expensive. DC colours too? LOL... I bet it would be confusing for some when they encounter only 2 colored wires in a control panel - Black and Green/Yellow. Better to ask for something that matters - ONLY trade qualified electricians work on equipment and installation and testing in accordance to Code... and people that can be held accountable for their sub-standard work.
Sorry... error. I read copex as meaning that shitty Romex cable. Copex I've seen is a thin steel conduit/ paper lined ... sometimes has a plastic jacket - not very resistant to crushing or damage from some butcher drawing in wires rough as guts.
@@BTW... Really the copex is just a way to neatly organise the double insulated PV cables neatly when coming from the roof into the fireman's switch (shunt) in the attic. Where we are you have to have automatic disconnection within 1.5 metres of entering the house, wherever you choose to do it. The problem then is getting the cables back to a safe place to site the equipment, utility room is my preferred location, unless there is a garage of course. Equipment placed outside does not do well in Ireland. And I am old enough to remember identifying DC with red and white in Pyro.
Agreed very interesting.... From the view we have it looks like the duct is pact.... From your view do you think they left enough space inside? Fill factor is 40%?
Interesting video Jamie. I agree that PV Ultra would be a better cable to use now but if that install was from 10 to 15 years ago. I think PV Ultra from Doncaster has only been out for a year or so. Currently they offer 2 core and 4 core upto 10mm CSA and they do a SWA version aswell.
What is the rated insulation voltage of those PV cables? 1.1kV? There is your problem... idiots using any standard cable rated for 240/415 V circuits that has a lower insulation rating. Could be worse... some idiot using cable designed for 12/24V automotive use.
@@zjzoznyou can get panel disconnects that you install near the panels, they will disconnect under fault scenarios. They need a separate pilot signal I understand.
Hi. Love your video really informative. I have a question. If you have a new consumer unit fitted but your cables are still red and black... Is that against all regs?
Absolute brilliant Jamie, good content and to the point. Most of all, some actual f@#ing practical testing that people can learn from. Well done mate! 👍👏👏
I bet none of you have ever moaned about the cost of fuel right??😂 Or the price of a meal when eating out or 100 other things that you haven't thought about the training/ production/ experience that has gone into the final product. Everyone tries to save money unles stupid rich, its not that deep lol
