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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. :-)

Parents
  • 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.

Reply
  • 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.

Children
  • 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.

  • 0 in reply to gkenyon

    power line comms, while an abomination that should never have been allowed, from an EMC perspective, normally only puts signals between the L-N pair, and at fairly low levels compared to other line transients.

    Kit that complies to one of the common standards TIA-1113 (HomePlug 1.0), IEEE 1901 and. ITU-T G.hn (G.9960–G.9964)  should only be injecting signals at the level of 1.5 to 2V RMS when loaded to 100 ohms,

    like this chip, the JSL1571 for example..

    To be honest if the AFDD designers did not consider inter-operation with systems like this then they have dropped another clanger..

    M,

  • 0 in reply to mapj1
    mapj1 said:
    To be honest if the AFDD designers did not consider inter-operation with systems like this then they have dropped another clanger..

    It was only a question - and a note that it's been questioned in the US, where they have emissions requirements for EMC, but not immunity.

    So, it may have been considered ?

    BUT ... another consideration is that the powerline comms set isn't itself may not be conformant to EMC requirements, or has a fault. That isn't the fault of the AFDD manufacturers?

    I won't ask what the other "clangers" are considered to be.

  • 0 in reply to gkenyon

    Update.

    Thanks for all the replies.Very useful. 

    I had eleven AFDDs in the board. I replaced three with RCBOs.

    Now, other AFDDs are randomly tripping, but the RCBOs are not.

    I have returned and checked all the connections back to the meter, tightening them to the required torque settings. I also took a picture of the board. You can see the heat in the AFDDs; they’re not hot but hotter than the RCBOs—this may or may not be an issue; I don’t know. They seem hotter when grouped together.

    I could replace all the AFDDs with RCBOs, but I could be masking a potential fault.

    I’m waiting for a reply from the manufacturer on Monday. I’ll then contact the DNO.

  • 0 in reply to Stuff

    Looking at that picture, I'm wondering how many watts those AFDDs are using internally? I dont think it would be the current flow through them causing the heat build up, as the other breakers would be of a similar colour.

    What temperature is the brightest yellow?

  • 0 in reply to alanblaby

    It's not very hot. The image at the top left says 23 degrees. The microprocessor is likely generating the heat.

  • 0 in reply to gkenyon

    Lewden are aware of this.  They have found such devices to be problematic with AFDs

  • 0 in reply to Sergio Fernandez

    Hi Sergio, Could you please provide more specific details regarding the nature of these problems? I can't see on the thread what you are referring to.

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