we've been making sure that our studio up here in yorkshire is future-proofed and ready for the ev
revolution you can see that the yard here has already been tarmacked ready to receive any
electric vehicles that may need charging watch out for the video where this was being dug out
and the fun and games that gordon and gary had trying to dodge water mains and supply cables but
away from all the mayhem of diggers and rollers we need to think about keeping the ev charger
installation compliant there's a lot of specific dangers relating to the installation and use of ev
charge points and this product here from Matt:e can be absolutely critical in keeping you compliant
with the regs however the eagle eyed among you will have noticed that the earth conductor
or cpc as we should call it goes through the circuit breaker meaning that we're going to be
switching a protective conductor what's that all about well just before we answer that question
let's take a closer look at what's inside this enclosure and what each part does because there's
some devices in here that will be familiar to you some that won't and some that are a bit weird at
first glance so let's follow the incoming cable into the enclosure the first stop is one that
we can be totally comfortable with it's simply a four-pole isolator that the incoming three-phase
and neutral supply comes into to make your initial connection the incoming cpc is connected into this
din rail mounted terminal here which is pretty important as this whole video is about the cpc
and the hazards that it can represent under certain circumstances now let's keep tracing these
cables out here they go down to this 5-pole mcb which i don't believe is a combination of words
that i've ever used before because as we mentioned earlier in the event of a fault this device will
disconnect all three phases the neutral and the cpc so that's a little unusual in itself
but there's also an additional device connected to the side of the mcb which makes this unit
even more curious and that's this little actuator here now this has an input from the device up here
which we'll get to in a moment and when that input is triggered it will actually operate the mcb and
either disconnect or even reconnect the circuit depending on the circumstances and we can see
that demonstrated right here tracing the wiring from that actuator input brings us to this device
on the top rack here this is the really clever bit of this piece of kit because this is the part that
looks out for a pen fault just a reminder that a pen fault is when the combined neutral and
earth conductor in the supply cable to a property becomes broken or disconnected this will cause all
the metal work in the property that's connected to the main earthing terminal to become live
inside a property this is not great but as long as the installation has been done properly
all the exposed and extraneous conductive parts have become live at the same potential
making it very difficult to get a shock between them and also as you're inside it's unlikely
you'll make good contact with the literal earth so the shock risk is minimized however
step outside to where your nice shiny electric vehicle is charging up and all of a sudden the
bodywork of the car has become live you're making a good connection to the literal earth and you're
about to have a very bad day so to avoid people getting shocks under these circumstances we need
to make sure that rev chargepoint installation is done in line with regulation 722.411.4.1
of bs7671 now you may be aware from other videos that we've made including one on another
mati device for single phase installations that there's more than one way to provide protection
against a pen fault and this device complies with indent three of regulation 722.411.4.1
let's recap on what that says a pme earthing facility shall not be used
as the means of earthing for the protective conductor contact of a charging point located
outdoors or that might reasonably be expected to be used to charge a vehicle located outdoors
unless one of the following methods is used three protection against electric shock is provided
by a device which electrically disconnects the vehicle from the live conductors of the supply
and from protective earth in accordance with regulation 543.3
indent two within five seconds in the event of the voltage between the circuit protective conductor
and earth exceeding 70 volts rms due to an open circuit fault in the pen conductor of the low
voltage network the device need not operate if the voltage exceeds 70 volts rms for less than
four seconds the device shall provide isolation and be selected in accordance with table 537.4
closing or resetting of the device shall be possible only if the voltage between the circuit
protective conductor and earth does not exceed 70 volts rms equivalent means of functionality could
be included within the charging equipment note 4 annex 722 item a722.4 gives guidance on indent 3.
so that's a bit of a mouthful so let's break it down first of all we've spotted the reason
why we've got a 5-pole circuit breaker in the enclosure the opening part of the regulation
states that the protection must disconnect all the live conductors which in the regs includes
the neutral and it must also disconnect the protective earth now that makes sense doesn't
it because it's that conductor that's now become live with a pen fault and created the hazard
so mystery solved however it's really important when we read regulations that we understand the
specific words that are used so for example at this point did you notice the earth in
protective earth is lowercase and later on when it states that disconnection must occur
when 70 volts appears between the cpc and earth the e in that earth is capitalized
which in the regs means that it's referring to the literal planet earth that we walk around
on which brings us to our next question how does this device measure between the cpc coming
into the circuit and the literal earth that we walk around on as it has no reference to this
well the end of the regulation there gives us a hint by referring us to annex 722 and item a722.4
which tells us regulations 722.411.4.1 in length 3 describes a device that measures the voltage
between the circuit protective conductor of the electric vehicle charging equipment and
earth during a pen failure in the supply network the neutral of a tncs supply is no
longer considered to be reliably connected to earth and a device that measures the voltages
between the following points will fail to provide equivalent safety to the device described in one
point 722.411.4 point one in then three one the circuit protective conductor and neutral
two the circuit protective conductor and the consumer's main earthing terminal
suitable arrangements include measurement of the voltage between either a the circuit
protective conductor and a suitable measurement earth electrode or and this is where the open
technology from Matt:ecomes into effect b the circuit protective conductor and a reference point derived from the line conductors of a three-phase system provided that suitable precautions are also
taken to disconnect the device when the supply to one or more line conductors is interrupted so
this device here joins the three line conductors electronically which creates a star point giving
a voltage of zero volts this then effectively works as an almost perfect earth reference point
this technology is now patented in five different countries including the uk it's a bit like having
an earth reference electrode that isn't affected by changes in the seasons or moisture in the soil
then when a pen fault has occurred it will open these two little relay switches at the top which
triggers the actuator on the mcb to operate and disconnects the supply keeping the user
of the connected ev charge point safe during a pen fault it's a really clever way of keeping
installation safe and solves a problem currently in place for bs7671 which doesn't allow for indent
four of the regulation we just looked at to be used for installations with a three-phase supply
but did you notice at the end of the sentence in part b of a722.4 where it said that suitable
precautions also needed to be taken to disconnect the device when the supply to one or more
line conductors is interrupted well that's also catered for by the last element in this enclosure
and that is this test switch here it looks a bit like an interlocking door isolator for a control
panel but it's just a rotary switch and if you look carefully you can see that the black line
conductor is wired through it on the way to the bottom of the pen fault monitor when you operate
the switch it disconnects the black line conductor and the device will trigger the actuator again
disconnecting the 5-pole mcb one final point to consider is that if the property of this device
is installed in has the misfortune to experience a penfold the pen monitor continues to check the
relevant voltage if it remains below 70 volts for 3 minutes then the 5 pole breaker will be
automatically reset meaning you won't need an engineer's visit an important point to look out
for you can see in our installation we've used an armored cable with a built-in data connection
and of course the armoring in this cable is an exposed conductive part and will therefore require
connecting to the protective earth which we've achieved at this end of the cable however you can
see we're not using it for the earth connection to the charger and we definitely haven't connected
the outgoing cpc to the charger to it either because of course if we did we'd bypass the
protection offered by the 5-pole mcb and in the event of a penfold this whole arrangement would
be rendered useless so at the charge end we don't have a connection from the armoring to the cpc of
the cable it's only earthed at the supply end for three-phase protection this Matt:e device with open
technology incorporated is an absolutely solid way of complying with the requirements of bs7671
and keeping users of your installation safe it comes in a whole range of formats and variations
with options for rcd protection over current protection and isolation up to 100 amps per phase
so whatever your installation needs there's sure to be a solution to match but as always we want
to hear from you what are your thoughts on the various requirements for pen fault protection
have you installed any of this type of enclosure from mati as always please leave your thoughts
and questions in the comments section below and as always thank you very much for watching