consumer units installed in domestic dwellings should now be of a non-combustible material
or housed within a non-combustible enclosure industry took the route of going down the metallic
non-combustible style consumer units for Amendment 3 17th edition distribution boards moving away
from the previous plastic consumer units so they didn't go down the route of installing them in a
non-combustible housing so i have another box around the consumer unit or distribution
whichever you want to call it we went down the route of installing metallic distribution boards
the thinking was that the distribution board could draw anything up to 100 amps i think
of the cut-out fuse installed uh in a domestic dwelling being a maximum of 100 amps it could be
80 amps or 60 amps meaning the consumer units itself can be drawing anything up to 100 amps
therefore drawing the most amount of current in any electrical enclosure domestically so this
would be the largest center to draw current from then we go down the route and we look to
our previous video the requirement to use torque screwdrivers to set conductors of manufacturers
tightness and we can see here how that's failed on the bottom of a circuit breaker and the top
of a main double pole switch where potentially the connection has been either over tight or
under tight causing to generate massive heat that massive heat causing potentially a fire as we can
see in the plastic consumer unit the consumer unit has instantly almost melted and the fire
is spreading to the building where to overcome that we're installing metal plate consumer units
holding or housing the fire for longer periods of time with inside the metallic enclosure because
of the issue of installing PVC PVC twin and CPC cables into a metallic enclosure and therefore
having the potential for a soft wiring system to rub against the harsh metal plug
we can see that also where the wiring system is on the surface that glands have been introduced
to support the conductors and also the tails so we've got the tails now supported traditionally
the tails would just be positioned into a consumer unit with no additional support
meaning again that they could potentially be drawing 100 amps and potentially moving or
wiggling about into their connections on the top which again over a period of time can cause them
to work loose loose connection can cause a fire we're back down the route of the distribution
board causing a fire in the installation which is unacceptable so we've got now the fact that these
glands can hold on to the cables in this case the tails preventing additional movement okay and
cable glands to hold our PVC wiring still traditionally the wiring system would enter
the back of the enclosure the plates at the back here would be removed the wiring system would be
buried within the fabric of the building and the conductors coming to the back of the consumer unit
removing the need for surface mounted glands however in some installations
a surface mounting gland would be required the other benefit of the glands is that allegedly
according to manufacturers they help maintain the far rating of the metallic electrical enclosure
they also reinstate the IP rating remembering during our studies we must remember the iv rate
at the top of any electrical surface must be IP4X so objects exceeding one millimeter
cannot enter the top of an electrical enclosure we're looking at dust in that respect and the rest
of that enclosure whether it be sides front with a cover on or bottom must have an IP rating of IP2X
in real terms we're looking at not being able to stick our index finger into the remainder of the
electrical enclosure we'll develop that as we go through our levels and actually clarify that as
IPXXB for at the minute IPX4 on the top surface and IP2X on sides and front and bottom surfaces
in order to maintain the electrical integrity of any electrical enclosure not just consumer units
lights switch sockets except some of the thinking behind the moving away from a traditional plastic
consumer unit uh during amendment three of the 17th edition one regulations are
coming onto a domestic consumer unit now that's made of a non-combustible material so therefore
we've gone for the metal clad or metal consumer units we've kept the IP ratings correct as always
and we've supported cables again to further reduce the chances of an electrical fire
through vibration of conductors etc we've moved towards a torque screwdriver in a previous video
so manufacturers terminations are returned to the correct tightness not over tight or under
tight and again in order to reduce the risk of a file within such a heavy load center being the
consumer unity up to 100 amps other key points that we can point out while we're doing this and
we'll do another presentations as well is some of the features incorporated within the consumer unit
or distribution board whichever one i call it the main switch double pole or linked main switch okay
isolates both line and neutral and we call them together live conductors so
therefore they're simultaneously isolated so when you're operating switch both line and neutral
are isolated both live conductors in the consumer union so the consumer therefore is turned off
we talked about securing isolation in previous videos as well we have over current protection
in the form of a circuit breaker so we've got the what you might be calling the trip switches
in your early days but circuit breaker offering over current protection we've got additional
protection in this case offered in a couple of different ways RCBO's protecting several circuits
for earth faults and individual here RCBO offering RCD protection or earth fault protection for an
individual circuit rather than the RCCB for several circuits of protections those can be
used for additional protection because they are rated at 30 milliamps or less in this case both
the RCBO and the RCBO are rated at 30 milliamps and we'll look at additional protection as well
in a later presentation so that's some of the thinking behind the amendment three of
the 17th edition wiring regulations and why now all consumer units installed in brand
new domestic dwellings or where rewire has occurred in their domestic dwelling or the
consuming needs changed in domestic dwelling but we're now installing uh consuming it of
a non-combustible material so in other words we're installing a metallic consumer unit so