cheers pal yes yeah take that as challenge accepted young man
okay so that was Marcus normally every week Marcus sends me over his video footage so i can sit here
and edit it at my electrician's inspired table so this is a cable drum top and a conduit leg but
this week he's been a bit pressed for time so he said i've sent you some images and therefore the
word challenge came into it he said can you turn those images into a video that can explain about
the old consumer the customer had and the new one that he installed and the benefits of installing
that new one well i've accepted that challenge so i expect you to put as many comments as you can as
you go along all the things you spot that i don't mention in the video so let's see if i can turn
those pictures into the video hopefully we're going to see next so this is the original one
looks great from the first point the fact it's made of metal and we know our domestic consumer
units need to be made of a non-combustible material or installed within a non-combustible
enclosure and we generally go for that metallic consumer unit and this is made of metal so that's
the first thing that's good about the original consumer unit the main switch there on the right
hand side linked main switch or double pole switch for isolation in other words it's currently on if
we were to operate it it would go off and turn off the whole installation we expect to see one
of those within our consumer unit however it's also a residual current device it's an
RCD so we're thinking okay so if that's the RCD it should be offering additional protection
and from our classroom lessons we know that an RCD rated at 30 milliamps or less
will offer additional protection however this RCD is actually rated at 100 milliamps and therefore
wouldn't offer that protection and by having an RCD as the main switch the other issue is if it
does operate under earth leakage conditions it disconnects itself and all the circuits attached
to it and that's all six within the installation and that's not very good from a selectivity
point of view so all the lights and all the sockets etc would go off in the installation
and if it was at nighttime we would be plunged into darkness and obviously you'd have to return
to the consumer unit in order to re-energize all the circuits within the installation so that's
quite inconvenient to you and obviously leads to dangers when you're plunged into darkness
the over current protection devices we've seen a few times on the channel and in the classroom
are bs 3036 semi-enclosed rewardable fuses so in other words inside of there there are a couple
of attaching pins and a piece of thin copper wire attached between them and when there's an
overcurrent or a short circuit the actual copper itself will melt and disconnect the circuit and we
know they're not very precise devices they have a fusing factor of two which gives us some concerns
when doing our design and also when they do operate so you make a nice loud bang which
keeps you nice and awake but when they do operate it requires a level of skill in order to re-thread
another piece of copper wire through between the two terminals in order to re-energize a circuit
and is the customer going to select exactly the right size fuse wire so we can see
working from the right to left we go red red so 30 30 and then we go 5 5 30 30 are they going to
select the exact size fuse wire to replace say the 30 or the five or of all they've got is 30
amp reward fuse wire and they just put it into the lighting circuit and therefore create a dangerous
situation with it being over fused for its actual conductor size is going out maybe one millimeter
squared so there's some issues there that would need to be addressed and updated it doesn't always
mean when you look at a consumer unit maybe that's made of plastic and we're used to looking at maybe
those ones with two RCCB's on them it's not always unnecessary to have to have that upgraded just
because it's an older style consumer unit there's lots of other considerations before you decide to
change the consuming not just the fact it's made of plastic and now it needs to be made of metal
and we'll obviously address those throughout the time on the channel so let's see what the
new consumer unit can offer us compared to the old one so let's take a look at some of the benefits
of having this new consumer unit fitted and if we start on the far right hand side we've got
something that wasn't present in the previous one at all and that's a type 2 SPD or surge arrestor
so we've got a surge device installed there in order that we can offer some protection
for items that are in circuit so say plugged in so you've got your tv electronic components in
there you've got your mobile phone you've got your tablet you've got your games console PC you've got
the electronic equipment within the oven a boiler all of those are sensitive to over voltages so in
other words rising well above 230 volts within the installation and the SPD's job there is to protect
from those over voltages now they can be caused in a couple of different ways and we're going to keep
it nice and simple in this video so we can have a transient over voltage caused by atmospheric
conditions not onto the property so it could be a storm a lightning or electromagnetic storm
somewhere say in your town or village that ends up being dropped into the system by the time it gets
to you it's an over voltage and that can cause you a problem and that's probably not quite as common
as the other one being by switching loads so we've talked about before when we have a magnetic
ballast within a fluorescent light fitting that we drop a back emf across the tube and we've used
that in other videos and in classroom lessons in order to get it to strike well imagine you were
near some industrial works so maybe near a factory unit with lots of motors which are inductive loads
and they were turned off okay obviously that could drop that effectively voltage back into the system
at higher voltage than the 230 nominal voltage could appear into your installation and that
surge of voltage could cause damage to your electronic components or it could be the big
transformer so we know a transformer is a big coil and that's at the end of your street it's 11 KV
and that was turned off okay power cut in other words effectively the same thing happens again
we have that back emf or that dropping of voltage into the system and becomes a spike that could end
up at your property and damage those electronic equipment's plugged in pretty much most circuitry
now has some sort of electronic component and that could be damaged by that so by installing a type
2 surge protection device you offer a level of protection against that definitely not a lightning
strike on the building that's something completely different but it's that transient over voltages
that we talk about in the classroom so that's there on the right hand side you see the two
little windows in it are green they will change to red when that surge arrester requires replacing
so next to the SPD is the main switch or linked main switch or double pole switch all names used
in multi-choice questions and written papers so that's therefore means of isolation so by
operating that switch it's currently in the on position and we look at the windows there
they are red red for danger okay if you look at the far left hand side of the devices there is
a green window there in the off position so red for danger so it's in the on position and when i
disconnect that or other words operate that double pole switch it disconnects both the line conductor
and the neutral conductor because we know when we talk about them together they are live conductors
so when i operate the main switch inside of the consumer unit there i actually isolate all the
circuits to the left-hand side in other words i turn off the power within that installation by
operating that linked main switch or double pole switch so next to the main switch we have an MCB
a miniature circuit breaker offering short circuit and overload protection and it's a B type
32 amps remember they come as B's C's and D's and this is a B32 so it's 32 amps and that MCB is
feeding the SPD on the far side so that's the part of the circuit that just goes that short distance
to that SPD and i've got videos on the channel showing you how to connect up an SPD as well
and i'm sure we'll make more in the future next to that we start a row now of RCBOs residual current
circuit breakers so these are both an MCB and an RCD combined into one device and what's really
handy about having all of those elements in one is it removes one of the issues we had on the first
board to do with selectivity so if we look at that first floor lighting circuit it's a B6 so the MCB
element of it is a B type and it's six amps but it's also an RCD rated at 30 milliamps so that RCD
element will offer additional protection and if we look next to that it shows us what type the RCD is
and we know that RCDs come in four different types this is a type A and pretty much now the
minimum requirement to be installed so as you look at the RCDs that we have in the workshop
um or around the installations that you're installing as an apprentice you may be seeing that
older symbol which is just the simple AC waveform and that ac RCD now is pretty much impossible to
fit into an installation because if you've got any type of electronic components which we said we had
when we refitted our surge arrester is you can't use that type of RCD so A type is really now the
minimum that's quite important because as we look at the consume units in the workshop many of ours
have that ac waveform on them and we've got to say to ourselves if i was installing an RCD whether
it be an RCBO or an RCCB in an installation i should be looking at an A type one as a minimum
and that's the symbol i should be seeing on the item that i bought from the wholesaler and
therefore then installed just a quick explanation why it's an A type is a minimum now they can
withstand or handle up to six milliamps of DC now this is not earth leakage current that we've
talked about when we're talking about 30 milliamps for the RCD element this is for the AC circuit
that's gone out and it's connected to something that then becomes a DC item an led downlight
games console computer etc if there's a fault or a part of that circuit starts to break down
the DC element could appear onto the ac side and affect the ac waveform and these A type RCBOs or
A type devices can withstand up to six milliamps of that DC current being leaked back and still
perform correctly the other two types are F and B okay and we will go through those in more detail
in other videos so a type being the minimum so we've got a B6 so a B type breaker six amps
it's an A type 30 milliamp RCBO so it's offering additional protection as well as short circuit
and over current as well so we've got all of those built into one device so if that was to trip
it would only disconnect the first floor light and circuit and leave every other circuit in the
consumer unit energized so it gets over that selectivity issue between our RCDs that when
on our previous board the main switch which was an RCD tripped it disconnected all the circuits we've
now got the advantage of this one RCD under earth fault conditions trips and only disconnects that
circuit next to it you've got another B6 for the ground floor lights and then you've got a B32 for
the cooker a B32 for sockets which is likely to be a ring final circuit and then the end one is a B16
for a water heater so that was 16 amps 32 32 6 6 for those ones that are the RCBOs that are being
used and then we've got the ability to extend the wiring system that doesn't mean put an extension
on the building because we've left some spare ways so you've got a spare way there of a 32 amp type
B RCBO again A type 30 milliamps and a couple of breakers spare and a couple of blank ways as well
so what we've done here is unlike the original board that was completely full all six circuits
were taken up the board has been changed and allowed for the electrical system to be extended
by leaving five spare ways now kindly the electrician being markers has left an RCBO and
two breakers in there so that's quite handy if you come back to extend the circuits you might find
that a circuit's already there that you can use and obviously there's additional blanks in as well
so an exam questions often why would you want more ways within a board than you're using we're only
using six of the actual ways in here why would you want more spare ways well that's so you can have
future extensions to the wiring system another advantage of using individual RCBOs for each
circuit is the amount of natural earth leakage current you're allowed to have on a circuit
protected by an RCD so if we have an RCBO in an older style consumer unit say protecting five six
circuits the total amount of earth leakage current from all five or six circuits can be no greater
than 30 percent of the rated value of the RCCB so if the RCCB is rated at 30 milliamps because
it's offering additional protection the maximum natural earth leakage current from all of those
circuits it protects is just nine milliamps and we'll talk about natural earth leakage current in
other videos as well as in the classroom so that nine milliamps is not a lot when you've got six
circuits or five circuits that could potentially leak a little bit of natural earth leakage back so
that can cause you an issue as soon as you go over to as we have done in this board individual RCBOs
because of the RCDs for each circuit each of them so we take the first floor lighting can have a 30%
natural earth leakage current so what's 30 percent of 30 so 10% of 30 is obviously 3 and therefore 30
is 9 and that gives you your 9 milliamps but that means that one lighting circuit can have a natural
earth leakage current of 9 milliamps and then next to it the ground floor lights could have
a natural earth leakage current of 9 milliamps and so on as we do the cooker the sockets and the
water heater so that's another thing that makes it an advantage having individual RCBOs over the
old system where we had those RCCB's protecting several circuits at once also when the RCBO trips
it trips off four five six circuits if it's half the board as well so we can see how this consumer
unit is a strong contender for what we should be fitting when we're out there in the real world
compared to what we're probably doing within our workshop where we've got maybe that one RCD as a
main switch protecting a couple of circuits when we say doing a lighting circuit in a two way board
okay so in the reality it would be lovely in college if every circuit that we install is on
an individual RCBO but we've got to think why we'd want to do that so we've given some really good
reasons here haven't we we have a an A type RCBO we now know it can have a natural earth leakage
current up to 30 percent of its value so that being nine milliamps we know it increases our
selectivity in other words if there is a fault on that circuit say it's to earth and it trips itself
out it will only disconnect in this case maybe the first floor lighting and not disconnect any of the
other circuits that are actually healthy so it keeps those circuits on under fault conditions
also if there is a fault and say it's on the first floor lighting that keeps tripping maybe
it's an earth fault that actually from the electrician's point of view we've now already
identified the circuit with a problem on whereas if we've got RCCB's with five or six circuits and
that's tripping out we've obviously got five or six circuits to start the investigation process on
so that's another advantage of using those RCBOs so i've tried to relate that to the real world
you've turned up an installation all the circuits are energized and working and you're trying to
suggest that that consume unit needs replacing and we now can see some of those benefits can't
we by introducing the SPD what they didn't have before was that protection against over voltages
as well as obviously a different type of RCD protection that offers additional protection
that also means that only the unhealthy circuit will operate under fault conditions now we
haven't gone into some of the other things we mentioned in other videos about IP ratings
a key or tool to enter the enclosure but that's in a video called understanding my consumer unit
and all the information within there is very relevant to obviously today as well i just
wanted to add in those elements that we're not going to see in the electrical workshop are we
the likelihood is our RCD main switch will be ac and we should be now aware of the fact we should
be moving away from it and we should be aware of the fact that ideally in the electoral workshop
we should be using RCBOs of an a type as minimum to protect our individual outgoing circuits
so as always i hope this video has been some help