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 Reply
  • Maybe Grenfell, to say "We are doing something?"

    Even though it seems to be an appliance that caused the initial fire. Anyone who takes an appliance apart knows they are made to a (low) price point. Their moulded plugs are rubbish, the connections inside are tiny and loose. Yet they get away with it.

    Same with the plastic consumer units that were catching fire, but, we know,they couldnt catch fire, as the BS stated it should be made of self extinguishing or non-flammable plastic.But some did not meet the Standard, some Makers were making flammable plastic CUs.

    But the Electricians got the blame for loose connections (yes, there were some), and the CU makers didnt get taken to Court for supplying Goods that didnt meet the British Standard they were supposedly tested and certified for. And of course, the Makers then got more income, as metal CUs were called for in high risk places, so , what should have been a perfectly good plastic CU was changed due to the Manufacturers bypassing the Rules, and then they made more money because of that. Cynical, me?

Children
  • 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.