AFDD !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[Toneyz]

Sorry I don't know how to post up a youtube link but have a look at the John Ward one part 2 on AFDD's worth a watch.

 

[Toneyz]

It seems like a motorway crash barrier you don't know it will work until you hit it and hope it does its job.

 

[sparksfly]

Thanks Anthony for the very informative post....probably need Michael more on the case

 

[Spoon]

Thanks Anthony for the very informative post....probably need Michael more on the case

Not really informative mate. The test was a farce.. Read post #15

 

[Nigel]

Not really informative mate. The test was a farce.. Read post #15

It is quite alarming how these false videos are just taken as gospel by people as if millions of pounds of research would be wrong but an anorake in a shed with crap equipment is correct.

 

[Spoon]

It is quite alarming how these false videos are just taken as gospel by people as if millions of pounds of research would be wrong but an anorake in a shed with crap equipment is correct.

It's easy to make people believe rubbish, when they don't like thinks in the first place. It falls into their beliefs.

 

[netblindpaul]

I agree that the testing is not laboratory level, but would those arcs not be more akin to that which would be found in the real world?
Which is surely what matters rather than precise laboratory generated arcs from signal generators which exactly match the algorithms that the device is programmed with?
Spoon, you are correct with the current levels required.
My concern is that as Spoon suggests the minimum arc current is 2.5A, now we are being told that we should fit these in places where there is an increased risk of fire, and external influence BE2 is mentioned, an enhanced risk of fire due to the nature of processed and or stored materials.
Now we are already required to fit a 0.3A RCD in these situations.
Now 0.3 A to (humour me please) 3A, which is 2.5 rounded up. is a change of an order of magnitude.
If, the maximum fault energy to cause a fire is required to be limited by an RCD to 0.3^2 x t, then why is it allowed to be 2.5^2 x t for an AFDD?
Could this be because the technology was "invented" in the USA, and it is fundamentally flawed, considering the guy who "invented" it has stated that it doesn't work, it seems that the manufacturers have done a good selling job to the committees.
Also, it won't work on a ring circuit, but, we still have to fit them because "it is there to protect against appliance faults", that is a quote from one of those "in control" of the industry.
So we are now having to fit a device that costs the customer like £1 per circuit per year, on every circuit, and we are supposed to be reducing carbon emissions, and saving energy...

I'm not saying that JW's videos are perfect, but, there is a lot more research that needs to go into this to prove that these devices are fit for purpose surely?

Think about it, if the AFDD costs £1 per year, 10 circuits £10, now if these are coupled with an electronic RCBO, is that another £1 per year?
Remember not all RCD's are now made on the old torroid coil principle, many have microprocessors and current sensors with AtoD converters etc. so they need power to work, which is why they must be connected in a specific line/load configuration.
So is that £20 per year, per household, think about this, multiply that by basically every circuit in the country...
These are also, not as sensitive or well proven as RCD's either, so can we rely on them for protection?

Please note, I'm not looking for an argument, more for a well rounded debate.

 

[Nigel]

JW should have been honest in his video and said that the device is not made to trip at these levels. I suggest he actually did not know they were not supposed to trip at those levels and niether did 99% of us.

A good job by the manufacturers and a poor job by us for taking things as gospel.

Well done Spoon.

 

[Spoon]

I can't take the credit for this @essex as it was a mate at work that pointed it out to me. I was initially a sheep, like most, who believed that the AFDD's should be detecting most arks.
As @netblindpaul has pointed out "If, the maximum fault energy to cause a fire is required to be limited by an RCD to 0.3^2 x t, then why is it allowed to be 2.5^2 x t for an AFDD?"
I presume it's down to cost. When you look at how the AFDD's detect arks then if they were to detect 30mA then there is going to be lots of nuisance tripping, unless the detection device is more fine tuned. This will increase the cost of these even more.

 

[Spoon]

If, the maximum fault energy to cause a fire is required to be limited by an RCD to 0.3^2 x t, then why is it allowed to be 2.5^2 x t for an AFDD?

Just to put it into context, if it was a 32A AFDD then it would be about 5A

 

[Toneyz]

J.W. has just posted the third video with an electric heater and it still did not trip. RCD's are ok for faults to earth not sure regarding L-N and broken conductors. Look forward to the replies.

 

[netblindpaul]

Just to put it into context, if it was a 32A AFDD then it would be about 5A

I know, I have access to the standard.
I used 2.5, because it is, the, minimum detection level in the standard.
I took this up with “the industry” at Elex Alexandra Palace in 2018, I took this up with the IET just after the DPC for the 18th was published, outside my comments on said DPC.
There have been no explanatons, answers to my concerns, nor justifications forthcoming from the IET, nor the manufacturers.

 

[Deleted member 26818]

Yes, 30mA RCDs detect imbalances between Line and Neutral, not loose terminals or broken conductors.
RCDs have lower current threshold because they are intended to prevent electrocution.
AFDDs on the other hand are intended to prevent fires.

 

[netblindpaul]

Don't forget, I mentioned nothing about additional protection by RCD, i.e. a 30mA device, I was referring to 0.3A devices, 300mA, for prevention of fire, as per BS7671 clause 422.3.9.

 

[netblindpaul]

J.W. has just posted the third video with an electric heater and it still did not trip. RCD's are ok for faults to earth not sure regarding L-N and broken conductors. Look forward to the replies.

You are correct, in that RCD's do not protect against series faults, such as broken conductors, we have MCB's to protect against L-N faults.
However my issue is that we are only allowed the energy from a 300mA device in a parallel arc from L-E, but, 2.5A minimum in a series arc...

 

[Deleted member 26818]

Don't forget, I mentioned nothing about additional protection by RCD, i.e. a 30mA device, I was referring to 0.3A devices, 300mA, for prevention of fire, as per BS7671 clause 422.3.9.

A 300mA RCD is not going to trip in the event of a fire, until the cables have melted enough, to allow earth leakage to occur.