For those who like to be ahead?

[Andy™]

Yep!

Also you won't have any really easy method of diagnosing the fault.

i was thinking the same thing. how exactly would they be tested? (well, im guessing they will be 'tested' very often), and im guessing we now need a new but of test kit costing thousands to be able to diagnose the fault?

also, will the requirement to avoid nuisance tripping be removed or does that automatically mean these new devices have a get out clause to not install them?

 

[Tony S]

Until recently the only test method was the test button. The manufacturers in their infinite wisdom don’t want you to know how the test function works.

 

[Sidewinder]

The issue is Andy, arc faults are intermittent, and truly chaotic in nature, look up and check out chaos theory to see what I mean.

Thus there is no specific pattern that they can detect.

They also detect stuff across a ide range of circuits so, narrowing this down becomes near impossible as they will detect faults in appliances too!

 

[Andy™]

maybe, just maybe, amd 3 was in preperation for when these new devices create an arc when teh test button is pressed, then fail and catch fire. then we already have the LFB approved board to contain it?

The issue is Andy, arc faults are intermittent, and truly chaotic in nature, look up and check out chaos theory to see what I mean.

Thus there is no specific pattern that they can detect.

They also detect stuff across a ide range of circuits so, narrowing this down becomes near impossible as they will detect faults in appliances too!

i know exactly how hard arc faults can be to find, ive done enough fault finding trying to find similar stuff, all with completely different characteristics, that do not easily identify where the problem is, and have completely erratic readings.

in theory its a good idea, but in reality the technology doesnt appear to be good enough for this to work correctly yet.

maybe 18th amd 1 is to remove the requirement for them whilst hoping no-one notices?

 

[steptoe]

and all you nay sayers told me that snake oil couldnt be sold,

X(

 

[Essex1]

Late one steps?

 

[binky]

looks like the regs are now being written by desk jockeys who find 'great ideas' on line....

 

[Blue Duck]

I don't even think they can use the Internet, the IET forums and the lack of actual comuication from the IET to its members would be a clue, Also there is the quality of their digital regulations which questionable.

It appears they form their ideas whilst lunching on dodo egg sandwiches with the rep from schnider or perhaps on the golf course with the heated ball washers with the electrium rep or in the peppermint hippo with the GE rep.

:C

:lol:

Don't get me wrong I have the upmost respect for IET members but it appears that the rule makers are in a league of their own alongside bent politicians and EU bureaucrat's...

:coffee :coffee :coffee

 

[binky]

they have to keep finding 'ideas' to keep changing regs to justify thier existence....

 

[ProDave]

Well I recon this will spell an end to Flourescent lights, they DO like to make a switch arc when they turn off.

 

[Tony S]

RCD’s in the 14th edition were a recommendation, AFDD’s were a recommendation in the 2002 NEC code cycle. Now they are mandatory for certain applications (most 120V domestic circuits). How long will it be before they become a requirement?

The bottom line is the bloody things don’t work! The entire concept is flawed.

 

[Evans Electric]

How did we manage without them ? 

Heaven forfend that one should think that manufacturers are lobbying the IET  ....one wouldn't want to think that , would one ?  And yet , where would this suggestion come from , certainly not the Rank & File , so who would it possibly be I ask ?  

Not your average electrician on the street . So who do we have ?

The IET itself .. :C

The manufacturers of the devices :C   Perhaps they make them but nobody buys them because we didn't know we needed them before

I cannot think of anyone else who would want to introduce them to be honest.

Would the IET  come up with this on their own ?  If so why wait until now?

Naw !! It has to be the London Fire Brigade doesn't it ?     They write the Regs now , don't they?

 

[Tony S]

I did some drawing of the test methods used for UL and BS-EN accreditation for an American forum. To say they’re Heath Robinson would be an insult to a great man.

I’ll have to dig the drawings out and write the text to go with them. To be honest the main parallel test I can’t see how it works without a kick start impulse voltage. Series arcs are easier to replicate and get started, the trouble is they equate to turning off a fridge.

UL = US Underwriting Laboratories

In the 80’s I did some insulation tests on 600/1000V 1.5mm² T+E, it failed at 17.5kV. You’ll see the relevance later.

 

[Tony S]

I’ve not found the drawings yet.

One thing that puzzled me about the parallel arc test, to propagate an arc you need either a break over voltage or a conductive path. The test for fixed cabling involves cutting a slit in the line conductor’s insulation parallel to the CPC. The cable is then bound with glass tape to the original serving cross section, over the glass tape two layers of insulation tape are applied.

I’m sure we’ve all come across cables badly made off with cuts in the insulation that have sat there for donkeys years and not caused any trouble. OK if damp gets in it most likely will go bang.

So to get the arc going we need to cheat a little, it’s also the reason I mentioned the 1.5 failing at 17.5kV.

This is from UL1699 (the BS-EN may as well be a photocopy)

Don’t forget the cable has been cut prior to this.

A 15 kV center tapped gas tube sign transformer is used to provide a 30 mA current source for creating a carbonized conductive path across the insulation of the cable specimens.

They are providing a break over voltage to cause a conductive path.

Fred Carno eat your heart out

 

[kerching]

So,if we have not got a neon sign tranny connected at home we are ok then? :slap

 

[steptoe]

Late one steps?

nah,

was an early one last night  

 

[Tony S]

So,if we have not got a neon sign tranny connected at home we are ok then? :slap

It just shows how concocted the testing requirements are for EU and US standards.

The working electrician’s (empty) pockets will fill the various pockets of the manufacturers while they feed their lapdog IET titbits.

 

[Essex1]

At least people can stop moaning about non-combustible CUs now.  That is getting tiresome.

As the US have been using these for some time now hopefully most of the bugs will be sorted before they are finally released here.  We also do a lot more in-depth testing here prior to putting a circuit into use which should help.  

 

[Sharpend]

RCD’s in the 14th edition were a recommendation, AFDD’s were a recommendation in the 2002 NEC code cycle. Now they are mandatory for certain applications (most 120V domestic circuits). How long will it be before they become a requirement?

The bottom line is the bloody things don’t work! The entire concept is flawed.

Essex did you not read the whole thread??

they might look nice but if they don't work then the point is? 

 

[Essex1]

Essex did you not read the whole thread??

they might look nice but if they don't work then the point is? 

BS7671 is full of stuff that is completely pointless.