Amendment 2 and AFDD's

[Dave Appleby]

Hi.

Been reading the but around 427.1.7.

Does anyone have any idea on retrospective application?

Is this going to apply to every board change or just adapted to new builds and then as a C3 recommendation for everything else?

Given prices it's going to be a massive cost change on a board swop. Plus, I know for certain I'm going to have space issues with anything over 30 years old here in Fife.

Thoughts?

 

[IAmSparkytus!]

When are they looking at bringing amendment 2 into play and will the changes be announced prior to that?

 

[newfutile]

it comes out on 28th March 2022 there is usually a 6 month overlap after that

 

[Sisyphus]

Any arcing to earth produces a current imbalance which trips the RCD. You don't need to look at the current signature on the active to do that, nor does said current signature analysis need to discriminate between a vacuum cleaner motor vs an actual fault.

isn't that the sdame for an afci?

~S~

 

[pc1966]

isn't that the sdame for an afci?

Not quite.

An RCD will detect a "parallel arc" between L & E, as well as simple leakage due to non-arcing conduction. But it won't detect a fault between L & N (that is below the OCPD) nor a series arc where a small break in L or N has happened.

An AFDD should pick up the high frequency content of the arc and so trip on L-N faults and series arc faults. But other things also produce arc noise.

 

[Aaron b]

If they don't work on ring circuits and not required over 32amp and ineffective on lighting circuits afdds seem pointless.

 

[Sisyphus]

Not quite.

An RCD will detect a "parallel arc" between L & E, as well as simple leakage due to non-arcing conduction. But it won't detect a fault between L & N (that is below the OCPD) nor a series arc where a small break in L or N has happened.

An AFDD should pick up the high frequency content of the arc and so trip on L-N faults and series arc faults. But other things also produce arc noise.

thx PC
i had thought the main component was the same, a toroid .......at least to the extent of my reading......

as ro the 'frequency' and/or arc waveform, we're told our AFCI incorporates a microprocessor with special algorithm software

the details of which, we're not privy to, but the testing lab methods we are>>>

This is what they used....a 'simulator;'.....

https://i.Upload the image directly to the thread.com/eOF06wB.jpg
Do RCD's have this manner of testing?

~S~

 

[pc1966]

The AFDD probably have a toroid as well, but it would need to be another in (probably) the L so it can detect the faults that a RCD is designed not to (L-N flow). By frequency I mean a typical earth faults sees a lot of 50Hz flow, but an arc typically has components to over 10kHz.

As far testing - that is a sore point. In the UK electricians typically have a Multi Function Tester (so high voltage IR, few 100mA bond resistance, supply Zs, RCD trip, voltage, and probably phase rotation, maybe earth rod impedance via two spikes, etc) but I have not seen much sign of them being available to test AFDD. We are being told to trust the self-test button, etc. Yes, what a good idea...

 

[pc1966]

If they don't work on ring circuits and not required over 32amp and ineffective on lighting circuits afdds seem pointless.

I can see some cases for them, but the cost/benefit looks very poor to me.

They do work on RFC but don't detect an open ring as practically no arcing takes place there as voltage difference is very small, however, they should detect arc faults on appliance cables that are attached that are above the few amps threshold.

But again, where is the evidence for their use? That is a proper analysis of fire (or near fire fault) cases that clearly would have been stopped by an AFDD and not things like lint fires in tumble dryers, etc.

 

[pc1966]

Broken web site duplicate post
stupid 50 character limit

 

[IAmSparkytus!]

Is anyone else having problems with the website? This is the only place it's letting me click on/post a message! ?

 

[IAmSparkytus!]

Is anyone else having problems with the website? This is the only place it's letting me click on/post a message! ?

 

[AJshep]

I can see some cases for them, but the cost/benefit looks very poor to me.

They do work on RFC but don't detect an open ring as practically no arcing takes place there as voltage difference is very small, however, they should detect arc faults on appliance cables that are attached that are above the few amps threshold.

But again, where is the evidence for their use? That is a proper analysis of fire (or near fire fault) cases that clearly would have been stopped by an AFDD and not things like lint fires in tumble dryers, etc.

I agree, I know alot of electrical fires are due to faulty white goods, there has been talk that it is in fact the white goods industry are pushing for us to incorporate AFDD to protect plugged in equipment.
It all seems like a box ticking exercise to me, there's no data I'm aware of.

 

[Resu]

I agree, I know alot of electrical fires are due to faulty white goods, there has been talk that it is in fact the white goods industry are pushing for us to incorporate AFDD to protect plugged in equipment.
It all seems like a box ticking exercise to me, there's no data I'm aware of.

Maybe we should be pushing for the white goods industry to stop throwing cheaper & cheaper components into their appliances then we wouldn't have this problem!

 

[Cookie]

isn't that the sdame for an afci?

~S~

AFCIs used to have 30/50ma ground fault protection in them, but some of the US manufacturers took it out in favor of looking at the current signature alone.

 

[Cookie]

I can see some cases for them, but the cost/benefit looks very poor to me.

They do work on RFC but don't detect an open ring as practically no arcing takes place there as voltage difference is very small, however, they should detect arc faults on appliance cables that are attached that are above the few amps threshold.

But again, where is the evidence for their use? That is a proper analysis of fire (or near fire fault) cases that clearly would have been stopped by an AFDD and not things like lint fires in tumble dryers, etc.

Funny you mention evidence. In the US, other than cut wire wrapped in glass tape and hooked up to a neon gas transformer in a laboratory there is zero evidence that arcing is behind any residential fires to begin with.

There is the case of firefighters opening walls to find smoldering studs with romex stapled across them. However, pyrophoric carbonization from an energized staple likely to be the real cause behind these events was and is miss-theorized into arcing. Ignoring the evidence of dried wood around nails and the foundation some distance from the smoldering area indicative of low level current leakage over the years and not arcing.