Debate about AFDD's continued

UNG said:

RCD's and RCBO's have a test button but on closer inspection with the appropriate tester they can be found to be out of spec like many I have found over many years in one case an RCD I had fitted 6 months earlier which tested ok when installed didn't test ok when I was doing some other work at the property

Until I can add a sensibly priced AFDD tester to my arsenal of test kit and definitively prove it's functionality externally then I don't see the value in having one yes it has a test button but does that sufficiently prove it is working and will work if an arc of the correct pre programmed signature and magnitude occurs

I don't unlike you with the total blind faith that you run with

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To be fair you can't test MCBs either, but you are happy to use them. Likewise SPDs.

DPG said:

To be fair you can't test MCBs either, but you are happy to use them.

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Yes you can the cost of the equipment to do it is prohibitvely expensive though https://cuthbertsonlaird.co.uk/36-circuit-breaker-testing

DPG said:

Likewise SPDs.

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Given that most SPD's are a single shot device if you tested them you would then have to replace it, although ther is a varistor test you can do to prove it will work if needed

UNG said:

Yes you can the cost of the equipment to do it is prohibitvely expensive though https://cuthbertsonlaird.co.uk/36-circuit-breaker-testing

Given that most SPD's are a single shot device if you tested them you would then have to replace it, although ther is a varistor test you can do to prove it will work if needed

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Yes, but you were talking about not accepting AFDDs until you had a reasonably pried tester.

When I posted

UNG said:

RCD's and RCBO's have a test button but on closer inspection with the appropriate tester they can be found to be out of spec like many I have found over many years in one case an RCD I had fitted 6 months earlier which tested ok when installed didn't test ok when I was doing some other work at the property

Until I can add a sensibly priced AFDD tester to my arsenal of test kit and definitively prove it's functionality externally then I don't see the value in having one yes it has a test button but does that sufficiently prove it is working and will work if an arc of the correct pre programmed signature and magnitude occurs

I don't unlike you with the total blind faith that you run with

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You replied with

DPG said:

To be fair you can't test MCBs either, but you are happy to use them. Likewise SPDs.

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When I replied with

UNG said:

Yes you can the cost of the equipment to do it is prohibitvely expensive though https://cuthbertsonlaird.co.uk/36-circuit-breaker-testing

Given that most SPD's are a single shot device if you tested them you would then have to replace it, although ther is a varistor test you can do to prove it will work if needed

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you came back with this

DPG said:

Yes, but you were talking about not accepting AFDDs until you had a reasonably pried tester.

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I'm really confused with your reply if I wanted to invest the money I could test MCB's, I already have a Metrel 3152 so I could / can test an SPD at the moment though even if I won the lottery there is no reliable AFDD tester available at any price

UNG said:

When I posted

You replied with

When I replied with

you came back with this

I'm really confused with your reply if I wanted to invest the money I could test MCB's, I already have a Metrel 3152 so I could / can test an SPD at the moment though even if I won the lottery there is no reliable AFDD tester available at any price

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It was just the point you seemed to be making that you didn't think you should use AFDDs unless you could buy an affordable tester.

DPG said:

It was just the point you seemed to be making that you didn't think you should use AFDDs unless you could buy an affordable tester.

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You made a point that MCB's and SPD's couldn't be tested I replied and I honestly believe from your reply that you never read it or understood it

With regard to AFDD's other than the self test button on the front please tell me how I can definitively identify a nuisance trip or a real trip or that the self test is working correctly on an AFDD so there is no doubt that it is functioning within the laid down parameters
Currently I can test all the functions of an RCD / RCBO with the appropriate test kit and definitively prove it is working correctly and within spec, for an SPD other than the indicator on the front as shown in the link I posted this can also be checked to show it is functional with a simple varistor test
Speaking to Megger some years ago on the subject of AFDD's and the testing of their functionality the opinion was it would be impossible to produce a tester that was consistantly reliable, then the question of is it a nuisance trip or a real arc fault came up and it might not be possible to find the arc fault point using traditional fault finding methods so the options would be to swap the AFDD or break the circuit down in an attempt to locate the issue if the problem persisted then consideration would have to be given to completely rewiring the problem circuit to eliminate any possible hidden joints in the existing circuit

The US has been installing AFCI's for many years and the feedback isn't that great as to whether they work or just create unecessary problems in the UK there is little absolute definitive evidence to support their use as the fire stats do not report or anaylse to that degree from what I have seen of them. From the potential arc faults I have seen over the years I have been in the industry there is probably only 2 or 3 where an AFDD may have been of some benefit all the other ocassions have been on main distribution equipment prior to where an AFDD would be installed

So other than the software driven self test and we all know how unreliable software can be can you tell me how I can reliably test the function of an AFDD

Sorry, I wasn't clear. I didn't mean that SPDs and RCDs cannot be tested at all, but that they cannot be tested with reasonably priced test equipment. Which is what you referred to when you spoke about installing/testing AFDDs.

I don't honestly know how good AFDDs are, but I do know that the people that make them have very clever developers and access to very high end lab equipment. I'm in no position to doubt what they say, regardless of what I might think.

Honestly not after an argument. It's good to debate things like this.

Edited to correct a silly mistake!

DPG said:

Sorry, I wasn't clear. I didn't mean that MCBs and RCDs cannot be tested at all, but that they cannot be tested with reasonably priced test equipment. Which is what you referred to when you spoke about installing/testing AFDDs.

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You did say SPD's and I did link to a youtube video that demonstrated this

DPG said:

I don't honestly know how good AFDDs are, but I do know that the people that make them have very clever developers and access to very high end lab equipment. I'm in no position to doubt what they say, regardless of what I might think.

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You would have thought that th US would have perfected them by now because they have been using them for many years. If I'm installing something the confidence that they will do what they are ment to do should a fault arise is important if they don't do it when needed then no doubt my credibility will be questioned by the customer

DPG said:

Honestly not after an argument. It's good to debate things like this.

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It is good to debate, but I don't buy into this blind faith with AFDD's especially with the number of out of box failures of RCD's / RCBO's I have found over many years, AFDD's being software driven just adds a new dimension to possible functionality issues

UNG said:

You did say SPD's and I did link to a youtube video that demonstrated this

You would have thought that th US would have perfected them by now because they have been using them for many years. If I'm installing something the confidence that they will do what they are ment to do should a fault arise is important if they don't do it when needed then no doubt my credibility will be questioned by the customer

It is good to debate, but I don't buy into this blind faith with AFDD's especially with the number of out of box failures of RCD's / RCBO's I have found over many years, AFDD's being software driven just adds a new dimension to possible functionality issues

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Doh, I typed RCD instead of SPD this time. It's been a long day!

DPG said:

Sorry, I wasn't clear. I didn't mean that SPDs and RCDs cannot be tested at all, but that they cannot be tested with reasonably priced test equipment. Which is what you referred to when you spoke about installing/testing AFDDs.

I don't honestly know how good AFDDs are, but I do know that the people that make them have very clever developers and access to very high end lab equipment. I'm in no position to doubt what they say, regardless of what I might think.

Honestly not after an argument. It's good to debate things like this.

Edited to correct a silly mistake!

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I tried a Hager AFDD on both radial and ring final with various currents connected via a socket outlet.

My conclusion was that they make little contribution to safety.

mainline said:

I tried a Hager AFDD on both radial and ring final with various currents connected via a socket outlet.

My conclusion was that they make little contribution to safety.

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I get that, but the testing done by the manufacturer and the approvals bodies will be wildly different to your home brew testing.

DPG said:

I get that, but the testing done by the manufacturer and the approvals bodies will be wildly different to your home brew testing.

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Admittedly but this was basically a real life situation let to run with a real loose connection fault creating a real arc that could cause a fire.

UNG said:

Yes you can the cost of the equipment to do it is prohibitvely expensive though https://cuthbertsonlaird.co.uk/36-circuit-breaker-testing

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This one maybe cheaper.

https://suvastika.com/the-mcb-testing-machine-a-valuable-tool-for-su-vastika/

mainline said:

This one maybe cheaper.

https://suvastika.com/the-mcb-testing-machine-a-valuable-tool-for-su-vastika/

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Not seeing a price?

UNG said:

Not seeing a price?

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Hence, why I said maybe It certainly looks cheaper.