so from the thumbnail to this video and that opening clip i'm sure you're aware we're going
to be looking at Arc Fault Detection Devices and to do that I've travelled down to Braintree to the
Lewden Palazzoli factory to catch up again with Ian Peacock because we know under amendment 2 of
BS 7671 18th edition wiring regulations the arc fault detection devices AFDDs conforming to bs
EN62606 shall be provided for a single phase ac circuit supply and socket-outlets rated
not exceeding 32 amps in high risk residential buildings houses of multiple occupancy
purpose-built student accommodation and care homes i'm so excited i can't wait to get in there to see
Ian's rig let's catch up with him to say i'm excited is an understatement now i've seen on
YouTube people in their back bedroom creating rigs that allegedly do or don't cause AFDDs to trip
but your rigging looks way more complicated it does Gary i'm excited to show you this
this is uh some rigs that we've created to demonstrate an AFDD RCBO in operation,
this rig is designed and pre-loaded with an AFDD RCBO and a normal run-of-the-mill
RCBO and we can switch either of those in circuit and connect them to our load device
via this switch here and then we're going to measure load current from the load device
right here is there a minimum current that will need to be seen through the AFDD for
it to operate yes uh AFDD the AFDD standard uh EN 62606 stipulates a minimum of two and a half amps
in order for the afdd element to work okay so and at the top here this looks very technical
is it i'm looking forward to this is the clever bit this is uh a carbon graphite rod we've got on
the left hand side here okay yeah and then we've got a copper rod here and we're able to adjust
the gap between those nice and finitely in order to create and draw out an arc there okay that's
probably what's not happening when people are creating their own ones at home because they're
probably going copper to copper does it suggest in the standards there must be a carbonization
yes this is this uh design is is taken directly from the EN 62606 standard where it stipulates
a graphite rod and a copper rod and the carbonization in the process would actually be of
the PVC am i right in thinking that that's correct as we've as we're getting uh excessive heating on
the cable we're burning that PVC and creating a carbon and it's that carbon that causes arcing
so now we've got power to the test rig and we can see we've got the AFDD connected in the circuit
via the switch here and the little lights on on the AFDD to tell us it's
in its healthy mode and what we're going to do now is we've got the load device we've got is
actually uh just a fan heater in this case and we're drawing near nearby 10 amps okay
so we're going to simulate a series arc for by adjusting the copper rod yeah and there we go
okay so it's gone off i can tell that because i'm not getting as warm as i was before the heat has
gone off obviously the AFDD is tripped now they're really clever aren't they because when you reset
them it actually tells you what type of fault you've got yes what we do is we open this door now
we reset the device i'll close the gap back up on the copper right and we'll clear the fork and what
we're going to see now is a flashing light on the AFDD and it's actually flashing once per second
it will do that for 10 seconds if the fault's no longer there and then it will go back to the
healthy position which is done now okay this label here which is going to be provided with each AFDD
RCBO will tell us those flashing light sequences and what they mean so before
we get into how the AFDD tripped and the thinking behind that you've swapped it over now to an RCBO
correct right we've disc we've disconnected our afd rc both from circuit and i've switched
it over now and connected my RCBO in series with this arc generator here so imagine now we're on a
socket outlet up to and including 32 amps and we haven't got afd protection and we get a
serial arc we'll see what happens to the RCBO under those conditions that's right what we've
got here is we're working with the same load same load current so we're going to adjust our arc here
okay well it has gone already the another one they've gone already yeah
this one is not finding it
and actually what we're going to what we're going to see here is our our carbon rod is
actually going to get quite hot now okay it's going to start to glow wow
it's doing nothing that RCBO so that's happening in circuit that's right and nothing's happening to
RCBO so that's got a risk of a fire isn't it yeah we know you can see there now we've measured we
measured this with a thermal imager actually we're generating sort of 200 degrees there
but these these type of force they can reach up to 6000 degrees I've just about recovered from the
amount of energy being generated by that serial arc when it was protected by what we like don't we
and our cbo was protecting our circuit that socket outlet circuit up to 32 amps
it did absolutely nothing did it nothing at all i mean you've got to remember with the series arc
for your you're not going to generate an increase in load current
right okay so therefore the device won't trip on overload it certainly wasn't an earth leakage
fault so what sort of protection is that AFDD giving us the AFDD RCBO is is offering four
levels of protection it's actually the it's it's the the ultimate device we've got at the moment
um it's so it's offering protection against over current yep by the short circuit or
thermal overload it will give us a visible current protection yes on pure ac or on the pulse 8 and dc
it will give us protection against arcing for whether it's a series arc or a parallel arc
and lastly it will give us a protection against over voltage or sustained over voltage over
voltage can you explain what level of overvoltage needs to be present in order for the device to
trip yeah the device it will respond to a minimum threshold of 275 volt okay so when it goes over
that will also trip under those circumstances correct it's a really clever bit of kit and
we've got a rig over here where we're going to look at an ac waveform and how it's effective
with the arc next our second test rig here is a device which we've got inside here a resistor
and a triac dimmer connected in parallel and they're going to generate a load current for us
which is going to be two and a half amps oh two and a half amps so that's the minimum required
in order to strip an afd and we used about 10 last time so that's nice to see now this looks
a little bit more complicated than the stuff i've obviously seen on youtube before and it
alters the ac waveform we've got a scope that shows us the ac waveform yes right here we've
got a signal generator connected to this rig and at present we've set this just on a
standard ac wave and what we can do actually if we if we press the button here what we're
going to see is a load current and we've got our afd connected in series with this okay so
that's going to be two and a half amps two and a half amps yep and we can see actually the afd is
doing nothing for us so he's quite happy with that nice and healthy the red um led says it's healthy
yep so what you're going to do next and our ac waveform is still the sine wave that we're used
to seeing agreed that's correct now this time what we're going to do we're going to modify this wave
and we're going to you can see now we've modified that now what we're seeing here now
is a typical signature that an arc fault would create on the electrical supply
okay so we're going to superimpose that okay over our load okay so that's going to that
waveform there is now going to be dropped across the electronic components of that afd they're very
clever so it'll see that new uh modified waveform little trip is that what you're thinking i have so
okay let's see then no pressure in there we go wow that was uh instantaneous wasn't it it's all
getting highly technical now i'm wondering whether we should have sent Joe Robinson down to shoot
this video with you ian however at home the wife turns on a hairdryer i can clearly see in the back
of that it creates arcs and i've gone to light switches before managed to rock them backwards and
forwards and i can hear that arcing effect in the back of it so you're telling me now if i've got an
AFDD on those type of circuits that it's actually going to disconnect no the AFDD won't disconnect
under those circumstances what you're seeing there within the light switch or the if you've got an
appliance a hair dryer portable drill you've got a natural spark as you it's a spark not an arc so
you're seeing a spark as you switch the light switch on or your motor is rotating in your drill
so the AFDD is pre-programmed with a firmware it's it's designed to look for those signatures
of those types of devices and actually it's going to ignore them that's a normal function
of the device so it's not going to alter the ac waveform if it's a spark as you call it and
not knock and we saw didn't we with the RCBO in circuit the amount of energy being produced and
it was quite visual as well that that's going to alter the AC waveform that's going to be picked up
by the device and trip you agree absolutely i've got one for you i've plugged in my hair dryer
and that's great in sparks and it's on a circuit that actually maybe has a serial arc in there
it's got two things going on now what's going to happen right we've got two things going on so
first of all the AFDD is obviously looking at the hairdryer and we're ignoring what's going on there
it's immune to tripping under that normal operation of that device yes but these art
cream thought that's happening in the fixed wiring the AFDD's even though that spark in an arcane is
sort of sparking is going on in the hairdryer the AFDD the AFDD has got to see and respond to the
arcing thought that's occurring in the fixed wiring and then under those circumstances
it would trip even though both it would disconnect the circuit that's a really clever bit of kit
right so the clevis stuff actually carries on inside the device so
what the device has got we've got a test button here which obviously simulates our RCD fault
which is as you would get on a conventional RCD or RCBO okay yeah but the device actually
as well it's got a self-testing function so when i energize the device yeah it's going to carry
out immediately a self-check on the AFDD part of the device okay and and there on every one
hour subsequently that that device is energized it will carry out this self-test okay what if it
fails its own self-test well it's looking for is it's obviously looking at its own components
within if it does fail itself test it's going to disconnect right okay and you go to reconnect it
but it's still obviously in real mode okay so if if i reconnect it um what i'm going to see
here if if the device is able to latch yes this led will flash at a rate of five times a second
for as long as that device stays connected but ultimately it will disconnect itself
once more so it's really clever so if there is a fault with it it'll just turn itself off and
there's a problem and you need to investigate and obviously at that point if there is a
an evident problem inside the device it's not something that's user serviceable so with Ian's
help i'm going to try and summarise what i've learned today so we know under amendment 2 of
BS7671's 18th edition of the warren regulations that socket outlets up to and including 32 amps
in certain locations will require AFDD protection we know they're recommended in other areas we know
they will clear series and parallel arcs they will they're looking for that high energy sustained arc
that causes carbonization on the cable and would ultimately lead to fire so we're looking for a
disconnection under those circumstances and under those circumstances we now know it affects the ac
waveform differently to a spark because it will see those sparks and not operate and it's looking
for those signature arcs and we saw one behind us then when we created all that energy we also know
the device is super clever because it will also protect us against residual currents and what else
over currents so a conventional like a conventional breaker short circuit thermal
overload residual current 30 milliamps um our arcing fault obviously series and parallel
and over voltage control as well yeah over voltage meaning we go above that 275 we also
know it needs 2.5 amps in order for it to actually operate as well but as always we're
interested in your feedback and your comments have you been fitting AFDDs recently and what
type of circuits you've been fitting on we'd love your comments are you considering fitting
AFDDs once it comes into full effect later in September please leave all those comments below
and we'll try and get back to as many as we can thanks for very much in that's brilliant thank you