Tackling AFDD Tripping

How are people tacking AFDD tripping?

In the past if I had a call out for a tripping RCD/RCBO or MCB there are well established procedures and tools to track down the fault.

These range from the visual inspection, insulation resistance testing, earth leakage measurement, RCD ramp testing and RCD time testing. It would not take too long to track down the fault whether it was faulty appliance, water ingress, damaged cable or even a duff protective device. The repair might have taken a bit longer but at least you knew where the fault was.

I had a call out this weekend for a AFDD that was tripping on a ring circuit. The new consumer unit (with 3- AFDDs, RCBOS and surge protection) has been in service the end of November and no issues reported. The customer did his own diagnosing and suspected the fridge/freezer as the circuit stopped tripping when he removed the appliance from the circuit. However, when he plugged the fridge/freezer in to another ring circuit with AFDD protection via a extension lead on a reel it did not trip. At this point I did not know what type of fault it was as the customer did not make a note of LED status on the AFDD.

The fridge has no damage and continuity and insulation resting testing all OK

Ring circuit was intact and insulation testing OK (greater than 500Mohm). The instrument readings were exactly the same as they were at the end of November. Plugged it back in and no tripping. I also ran a 1.8kW load on the same socket for a few minutes to see if I could get it to trip -  all OK.

Ten minutes after leaving the circuit tripped, I returned and from the flashing light sequence on the AFDD it was definitely an ARC fault. Reset the breaker and is was tripping regularly every few minutes.

I plugged in the fridge into another circuit, but this time with my much shorter extension lead. Then proceeded to inspect all sockets and checking tightness of terminals - no issues. Although there are some terminations not accessible for inspection.

Then I noticed the other circuit tripped (with fridge connected via extension lead) - so the conclusion that it is definitely the fridge. As the fridge/freezer is still under warrantee I advised the customer to contact the manufacturer. He plugged it into the original circuit in the hope to keep it running. It did not and I told him again to not run the fridge.

Later that night I get a message that now the other circuit is tripping every time they use the microwave -  not the circuit with the fridge and apparently fridge not plugged in.

At the moment I am not 100% sure it is the fridge and can't rule out a faulty AFDD or has the faulty fridge caused the  microprocessor in the AFDD to go faulty.

As a last resort I told them to switch off all circuits and main-switch and then switch-on one by one. Thinking that these devices have microprocessors maybe they need a restart every now and again - bit like my router at home.

Any suggestions on diagnosing ARC faults?

Parents
  • My understanding (which may well be incomplete or wrong) is that the standard's tests for AFDDs work on the assumption that once there is a break in a cable which causes intermittent arcing, the arcing chars some of the insulation over time, and the carbon makes future arcing easier. So the tests are with carbon rods. A lot of the youtube tests try to create arcs with small copper to copper gaps, which tend not to last more than a second or two, and may be seen by the AFDD as a motor-type spark and not trigger a disconnect.

    So when a youtuber shows an AFDD failing to disconnect, it may be that the AFDD is actually working correctly. Or it may be being completely useless. Or the standard isn't up to scratch. We can't tell from the video.

  • Mr Savoury has published another rather humorous Hager AFDD update -

    www.youtube.com/watch

  • Good points well made. Take a look at Mr Savoury's latest youtube missive on the AFDD subject linked above - he makes the point that Hager have, by making their devices firmware updatable, transferred the risk onto any installer who does not keep a keen eye out for any future firmware updates. Basically, you install a few hundred of these across several sites over several years and you are the one responsible if a fire or fatality results as a consequence of you not keenly monitoring and ensuring that every device you install has been updated, so it looks like a lot of tyre wear and diesel consumption for those foolhardly enough to purchase/specify Hager AFDDs both now and in future.No other manufacturer imposes this at present.

  • I wonder how often the firmware is updated? 

    Would an out of date firmware be a C3 on an EICR? (Does anyone here have a up to date copy of code breaker?)

    Does the firmware revision need to be checked on the EICR, manufactures instruction seem to lean this way?

    Is there a timeframe that the firmwares need to be doneby, can you jump more than one version?

    If you have a 16 or 20 way CU/DB and it take 5mins to update each AFDD who will pay for this time?

    Can you break the AFDD with a failed firmware update?  Years ago when I did firmware updates on a routers I would take a spare with me onsite.  Safe to say I bricked a few in my time.  To the same affect will the SPark need to carry a spare A6 B6 C6 A10 B10 C10 A20 B20 C20 D20 Hager AFDDs the list goes on.  I think the R&D team at Hager might need to have a look at this and get some imput from the electrician on the ground in the UK and not other EU countries and engineer a way forward.

    Enough bashing.  Now lets help.

    Hager may well have an idea with being able to upgrade the AFDD.  Fusebox found out the cost of a recall recently.

    Could the CU/DB have a bolt on kit to make it internet aware or connect to the internet?  Lets call it a hub.  This hub could interogate the AFDDs in the CU/DB and then report back to the user and/or the installer.  The hub only connects to a Hager secure portal and nothing else.  As with all things on/in the internet the security side is paramount as a compromised system means it could be managed from elsewhere maybe even shut down.  The installer/user could then click the button for a firmware update.  There is a caveat, no load must be connected to the AFDD during the upgrade. 

  • The road to hell is paved with good intentions - why make it way more complicated than it need be? And more pertinently, who will pay for the time and wear and tear for the travel to site every time a firmware update is issued?

    Just don't buy Hager, just buy a different brand until they drop their crazy irresponsible ideas about making everything have to connect to the internet. There is no need if the product is designed properly from the start - Other brands don't have to have web connectivity.

    What one man can do, another can undo, the web can never be totally secure.

  • The Saga continues.  David at DSES has done another follow up video on AFDD.  It is well worth a watch. 

  • This one 

    note that, as  with all Dave Savery Videos ,his language is not suitable for those of a sensitive disposition,
    or minors, or indeed any one  who works underground.

    Putting that to one side, and the fact it is rather long,  technically I find the content is fascinating, if quite worrying.
    'Nothing wrong with relying solely on inadeqauetly tested software'  has not panned out well for the Post Office or  Fujitsu recently, and I think  it may not do so for Hagar either.


    Mike.

  • Hi Mike

    Thats the video yes.  The language is colourful but I think the facts he brings up are very valid.  Like the Hagar test device that goes in the CU.  The fact there is still no firmware update despite the fact that people are reporting issues to Hagar.

    Should a fire arise from a Hagar AFDD not working correctly there will need to be a firmware update rolls out or possible a factury recall of all their (Smart) AFDD devices.

  • Should a fire arise from a Hagar AFDD not working correctly there will need to be a firmware update rolls out or possible a factury recall of all their (Smart) AFDD devices.

    I suspect that'll never happen - after all how could anyone demonstrate that the fire would really have been prevented if the AFDD had behaved differently? The fire may have been started by simple resistive heating at a bad joint or a conductor thinned by damage m'Lud - without any significant arcing being present - which of course no AFDD could ever reasonably be expected to detect. Prove otherwise their highly paid lawyers will say.

       - Andy.

  • Did you watch the video Andy?  Do you think that David at DSES has some valid points about the Hagar AFDD?

  • I saw the earlier one, and have skimmed the latest - yes there are questions I'd like answered. These big companies though are primarily there to make money for their shareholders - recalls or similar mass updates cost a fortune, so unless their position becomes indefensible they'll not spend the money. As long as they pass the tests required by EN 62606 or whatever (which I presume they do) I'm sure their lawyers will be telling them they're on safe legal grounds, whatever a bloke with a bit of lego and brass (or carbon) fittings comes up with.

    Nothing's perfect - it's reckoned around 7% of in service RCDs don't trip when the should, 'when they should' doesn't include lots situations that have residual d.c. currents - and even then there's 5% of the population that are aren't covered for shock protection.

       - Andy.

Reply
  • I saw the earlier one, and have skimmed the latest - yes there are questions I'd like answered. These big companies though are primarily there to make money for their shareholders - recalls or similar mass updates cost a fortune, so unless their position becomes indefensible they'll not spend the money. As long as they pass the tests required by EN 62606 or whatever (which I presume they do) I'm sure their lawyers will be telling them they're on safe legal grounds, whatever a bloke with a bit of lego and brass (or carbon) fittings comes up with.

    Nothing's perfect - it's reckoned around 7% of in service RCDs don't trip when the should, 'when they should' doesn't include lots situations that have residual d.c. currents - and even then there's 5% of the population that are aren't covered for shock protection.

       - Andy.

Children
No Data