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Multiple AFDD’s tripping.

Stuff

Hi all, I wonder if anyone can shed some light on an arc-fault-finding issue?

Installation details:

Large domestic property with a 42-way DB, a large Loxone (home automation) panel with it’s own 24V battery backup. Uniti Power Usymphony SPY300 provides UPS for two circuits (WI-FI & Medical equipment). Install with no issues since May 2023. A Riello SDH 3000 Sentinel Dual 3000VA is providing UPS to a home lift circuit that was added over a month ago.

Eleven Contactum 32A AFDDs are installed on all socket outlet circuits. RCBO’s on all other circuits

The property is located close to a small/medium-sized retail park.

The Problem:

The homeowner called on Monday this week to say that the kitchen electrics had tripped out. She then followed up with messages to say that the annexe kitchen had tripped, then the loft and then the bedroom sockets. All had tripped when appliances were operated. Sometimes a washing machine, toaster, kettle hover, etc. In all, four AFDD circuits tripping randomly.

Fault finding:

The kitchen AFDD stays up, but when I put on the kettle and the toaster the AFDD trips. If the fridge and toaster are on, the AFDD trips.  With the UPS systems removed, it still happens.

I removed both UPS systems before testing.

I tested the kitchen circuit; it was solid, with no issues. Earth leakage at the incomer was 23.55mA; on the kitchen circuit, it was 3.4mA with appliances on standby. I tested all the kitchen appliances under load, and the total leakage was approximately 3 mA. I ramp-tested the AFDD—23mA. I moved the appliances around the property and could see that they were not the problem. So, it was definitely an arc issue. Also, the LED status indicated an arc trip. Continuity tests confirmed no loose connections.

With all other circuits off. I cannot get the kitchen AFDD to trip.

Cause:

I spoke with Contactum technical, who were really helpful, but we couldn’t determine what was tripping the arc device.  Spoke to the NICEIC – they could not provide any support.

The fact that it has been in place for over a year with no issue, could it be a quality of supply issue from Nathoin Gird? The property has had a number of mini power cuts in the past – hence the UPS going in.

Any suggestions?

 

Thanks in advance. :-)

  • 0 in reply to AMK

    No, insurance companies will not accept it.

  • 0 in reply to Sparkingchip

    Thanks Sparkingchip, appreciate your advice. The AFDDs have been purchased and installed. The supply connection to the building is scheduled for completion this week. Have you had inquiries or issues reported concerning AFDDs? Additionally, may I inquire which brand of device you prefer ?

  • 0 in reply to lyledunn

    I think the caveat here is that the consumer REQUIRES a BS EN 62606 compliant fault to meet with their AFDD's operating metrics.That alone should give plenty of rise for concern.

    The test standard requirements are interesting insomuch that they actually require the presence of carbon to simulate damage. If the fault has to develop to such a point whereby burning is, or has already been present, then surely it's too late even if the AFDD actually trips.

    Should the scenario you describe above whereby the omission of devices contributes to a fire, I would be calling a very expert witness to give the actual reasons why. I suspect that they would flounder in the witness box at this first hurdle.

  • 0 in reply to AMK

    engx.theiet.org/.../fire-combustibility-exclusion-clause-professional-indemnity-insurance

  • 0 in reply to Sparkingchip

    What fire safety regulations are they referring to? 

  • 0 in reply to lyledunn

    I imagine it would be all encompassing, including BS7671.

    Probably best to avoid finding out the hard way.

  • 0

    Has the homeowner started using anything like powerline Ethernet links?

    I do know that sometimes SPDs cause powerline Ethernet links to fail, and have also seen "internet gossip" about "AFCIs" (AFDDs) also impairing them ... but also some suspicion of things happening the other way round - GFCIs operating when powerline transmitters are used.

  • 0 in reply to gkenyon

    If a powerline Ethernet adapter introduces noise or interference into the electrical system, an AFDD may falsely interpret this as an arc fault due to the irregular patterns produced, which are akin to those of genuine arc faults. Although AFDDs are engineered to disregard harmless arcing, they may occasionally exhibit heightened sensitivity to specific electrical disturbances that resemble hazardous arcs. This raises a pertinent question: Does opting for a less expensive AFDD brand increase the likelihood of experiencing unwarranted tripping due to its potential over-sensitivity to such disturbances?

  • 0 in reply to gkenyon

    "GFCIs" (AFDDs)

    GFCI = Ground Fault Circuit Interrupter = RCD. (AFCI = AFDD).

       - Andy.

  • 0 in reply to AJJewsbury
    AJJewsbury said:

    "GFCIs" (AFDDs)

    GFCI = Ground Fault Circuit Interrupter = RCD. (AFCI = AFDD).

       - Andy.

    Yes, sorry ... typo and edited as above

    Although ... RCDs too perhaps affected (may not be unwanted tripping though), because square waves used for digital transmission can have a DC component, and certainly a HF component.

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