The Arc Fault Detection Device… again.

Colin Jenkins:

Hello Everyone.

A very interesting thread.  For my family, I did a risk assessment with respect to the omission of AFDDs for our property when I replaced our consumer unit last year.  I've attached it here for information only as it reflects many of the discussion points that have been raised.  Just after I completed the CU change, Wylex released the single-module RCBO, so the point about changing to a duplex unit is no longer valid, but it certainly applied at the time.


Another aspect that came up in the Youtube videoes is that RCBO/AFDDs draw app. 1 Watt each continually.  That adds up to an unwelcome rise in temperature when a row of these are stacked side by side in a metal enclosure.

Regards,

           Colin Jenkins.Hilltop Cottage - omission of AFDDs Annonimised.docx

Just an observation/correction, if I've read it correctly, you're saying that affds won't detect arcs in the ring final ccts but will in the spur connected to the ring, but note that according to Hager*, parallel arcs are detected in rings, but serial arcs are not.

*https://hager.com/uk/support/regulations-18th-edition/arc-fault-detection-devices


On a different note, I get perhaps the erroneous impression from your Ax that there's a sense of overreliance on the ccts being 'monitored' by the rcd's which somehow minimises the need for afdds despite recognition in the preamble that they do different things. Cost aside, perhaps it's safer to install afdds than not.


Also, while the property may be occupied, and things turned off when people are out, there was apparently no factoring in of e.g. rodent damage in lofts or under floors, or of inspection and testing at regular intervals, which may be more frequent if in regular use, thereby detecting things like loose connections which can't be detected by home users. So perhaps afdds may help where inspections are few and far between - if they actually work as billed/intended of course.

Colin Jenkins:

Hello Everyone.

A very interesting thread.  For my family, I did a risk assessment with respect to the omission of AFDDs for our property when I replaced our consumer unit last year.  I've attached it here for information only as it reflects many of the discussion points that have been raised.  Just after I completed the CU change, Wylex released the single-module RCBO, so the point about changing to a duplex unit is no longer valid, but it certainly applied at the time.


Another aspect that came up in the Youtube videoes is that RCBO/AFDDs draw app. 1 Watt each continually.  That adds up to an unwelcome rise in temperature when a row of these are stacked side by side in a metal enclosure.

Regards,

           Colin Jenkins.Hilltop Cottage - omission of AFDDs Annonimised.docx

Just an observation/correction, if I've read it correctly, you're saying that affds won't detect arcs in the ring final ccts but will in the spur connected to the ring, but note that according to Hager*, parallel arcs are detected in rings, but serial arcs are not.

*https://hager.com/uk/support/regulations-18th-edition/arc-fault-detection-devices


On a different note, I get perhaps the erroneous impression from your Ax that there's a sense of overreliance on the ccts being 'monitored' by the rcd's which somehow minimises the need for afdds despite recognition in the preamble that they do different things. Cost aside, perhaps it's safer to install afdds than not.


Also, while the property may be occupied, and things turned off when people are out, there was apparently no factoring in of e.g. rodent damage in lofts or under floors, or of inspection and testing at regular intervals, which may be more frequent if in regular use, thereby detecting things like loose connections which can't be detected by home users. So perhaps afdds may help where inspections are few and far between - if they actually work as billed/intended of course.