AFDDs are a massive fraud

[Cookie]

Derailed another thread with AFDDs, so I am starting this one. I will simply say that UK RCDs and MCBs provide arc fault protection as is. UL not only knows that, but extensively researched UK power systems in an effort to emulate the very same concept 40 years. One the simply fact (growing concern) that the US National Electrical Code does not prohibit a maximum earth fault loop impedance.

 

[Deleted member 26818]

Perhaps I’m cynical?
The 18th edition now has a number of requirements or advisories which appear to have nothing to do with safety, but are more to do with increasing profits for manufacturers.

We can now no longer use anything other than a Type tested DB in domestic installations.
That means we cannot use items of equipment from different manufacturers, even if all of the items of equipment have a greater breaking capacity than the measured PFC.

We now have to follow Manufacturers’ Instructions in respect of DBs.
This means we have to install items of equipment rated at what the manufacturer’s require, rather than rated according to the expected load.

BS7671 now no longer lists RCD sockets or RCD FCUs as being acceptable for additional protection.
This means many installations will require a new DB be installed just to provide RCD protection for an extra socket.

BS7671 now requires circuits supplying luminaires be provided with RCD protection.
So again a new DB when installing an extra light.

We are now advised to install SPDs to prevent damage from lightning strikes.
This is despite the fact that damage to consumer installations from lightning strikes is very rare and occurs much less often than damage caused by loss of supply neutral.
Is it a case of safeguarding the DNOs against compensation claims, rather than protecting customer’s equipment against lightning damage?

As for AFDDs, my understanding, is that they are very unreliable and won’t work with RFCs.

 

[Cookie]

It will only get worse unless people put a stop to it. They count on your silence and compliance as consent. US electricians are starting to see the light. Another case in point:

Equipment Grounding question

All, Please see picture attached. Is this the correct size grounding conductor required for equipment grounding? 2 of the power panels have 100A main breaker and the other 2 have 150A main breaker. The transformers are 25KVA. The Fiber panel is a Corning ICH-12P, Nema 3S, I believe. A #4 seems...

forums.mikeholt.com

The GFCI requirements are coming from people getting killed on none compliant installations. So how will mandating more GFCIs solve the issue of people refusing to follow the code in the first place? And speaking of that handy work is getting worse because home owners don't understand why an electrician costs 5x as much with call backs vs a handy men that won't cause $500 worth of groceries to go bad when the fridge AFCI trips.

https://www.hbag.org/uploads/5/7/9/1/57910935/technical_service_pointer.pdf

 

[marconi]

Cookie - please indulge me - where are you in the USA, at least by state if not city/town?

You have sparked off a good discussion and getting some fine folk contributing and following.

 

[gutterball]

Have a look at the John Ward videos on youtube when he tested one.

 

[Cookie]

Have a look at the John Ward videos on youtube when he tested one.

Yup, saw them. And a perfect example of why they don't work. Most appliances draw less then 5 amps and most circuits are loaded below that as well. Joule heating can take place under 1 amp. So right here we do not have any fire protection, and above 5 amps its hit or miss... because it may just be an appliance doing its normal thing.

Which brings me to the arc detection logic itself. You need the computing power of at least an Iphone to get reliable discrimination. And even then the AFDD must be programmed to take into account thousands of benign waveforms "learning" what is ok and what isn't. The whole concept even with the right intentions is impractical. Maybe as computing power increases and cost decreases but till then- no.

 

[Pete999]

Yup, saw them. And a perfect example of why they don't work. Most appliances draw less then 5 amps and most circuits are loaded below that as well. Joule heating can take place under 1 amp. So right here we do not have any fire protection, and above 5 amps its hit or miss... because it may just be an appliance doing its normal thing.

Which brings me to the arc detection logic itself. You need the computing power of at least an Iphone to get reliable discrimination. And even then the AFDD must be programmed to take into account thousands of benign waveforms "learning" what is ok and what isn't. The whole concept even with the right intentions is impractical. Maybe as computing power increases and cost decreases but till then- no.

If anyone doesn't know what Joule heating is here is a description

joule heating - Bing

Intelligent search from Bing makes it easier to quickly find what you’re looking for and rewards you.

www.bing.com

Although quite what it has to do with AFDDs is questionable to say the least

 

[static zap]

If anyone doesn't know what Joule heating is here is a description

joule heating - Bing

Intelligent search from Bing makes it easier to quickly find what you’re looking for and rewards you.

www.bing.com

(That one put me to sleep.)
100% Efficient conversion of electrical energy to heat,
in a region of high relative Resistance ,
I squared R Losses . (or am I wrong)

 

[Cookie]

(That one put me to sleep.)
100% Efficient conversion of electrical energy to heat,
in a region of high relative Resistance ,
I squared R Losses . (or am I wrong)

Here is an easier way to understand it:

 

[telectrix]

now you know why we call them fire nuts.

 

[Devonchris]

Very interesting thread. And no doubt there are hundreds of firefighters throughout the country breathing a sigh of relief now that they know these things don't work.

They were all thinking they would have to start doing a proper fire investigation instead of the old standby, cause of fire, "electrical".

 

[Cookie]

Very interesting thread. And no doubt there are hundreds of firefighters throughout the country breathing a sigh of relief now that they know these things don't work.

They were all thinking they would have to start doing a proper fire investigation instead of the old standby, cause of fire, "electrical".

In the US most fires are written off as "electrical". Unless arson is suspected the fire is not thoroughly investigated. And even then its hard to find a cause when all you have is a pile ashes. So fire statsitcs from the states are very skewed.

Interesting fact: fire sprinklers are actually mandated in US homes but its amended out at the local level 99.99% of the time.

 

[Devonchris]

The Brits have long complained that many Americans don't get irony (for instance, we published a telling story from a British expat last week, and then there was the time the editor of Business Insider UK griped on Twitter about his literal American editors).
Well, there's a reason we don't get irony, and it's not because we're daft.

the British, despite being more low-context than many cultures, are far more high-context than the Americans. Thus they will often say things with implicit meanings that are contrary to their literal meanings — aka irony — that go right over American heads.

Here's The Real Reason Americans Don't Get Irony

There's a very good historical reason.

www.businessinsider.com

Nothing personal, it's just me. I'm retarded, and am only here for the humour

 

[Devonchris]

Sorry, that should read, RETIRED.

 

[telectrix]

Sorry, that should read, RETIRED.

you were right the first time. .

 

[ipf]

you were right the first time. .

'Just kidding', tel?