in this Q and A video we're going to answer the question do I need to carry out an EICR
before replacing a consumer unit firstly good news it is not a requirement to carry out an
EICR prior to the replacement of a consumer unit but it would in truth be a good idea as
it could stop any disputes with clients the extremely experienced and knowledgeable eFIXX
community will be well versed with the it worked before you got here scenario this is an all-round
negative situation for the electrician as it can leave a sour note between the parties being out
of pocket financially and leaving you with no real means of retaining the client for future
work the most important benefit of conducting an EICR is that it aids in the smooth running
of the project when it comes to installation there are a number of essential pre-checks that
need to be made before commencement of the work primarily it needs to be established that the
rating and condition of any existing equipment including that of the distributor is safe and
suitable enough to cope with the alteration being made by replacing the consumer unit
this means checking that the consumer meter tails are of an appropriate cross-sectional area for the
type of system present and that the earthing and bonding arrangements are suitable for the
safety of the proposed alteration being made for example a measurement of external earth fault loop
impedance or Ze should be made if practical to ensure that the installation is suitably
earthed as per regulation 8 of the electricity at work regulations if the earthing conductor is
not acceptable this directly impacts the proposed alteration if the defect is not found before the
work commences it would lead to a situation where the electrician can't energize the installation
after fitting the new consumer unit till such time that the earthing supply is rectified in general
if the meter tails earthing and or bonding arrangements are deemed to be inadequate to
support the proposed alteration of replacing the consumer unit then the client must be advised as
to the need for upgrading work if the client refuses the necessary work the electrician
should not proceed with a replacement consumer unit until the necessary remedial work has been
completed regulation 132.16 is clear on this point no additional alteration temporary or permanent
shall be made to an existing installation unless it has been ascertained at the rating and the
condition of any existing equipment including that of the distributor will be adequate for the
altered circumstances this includes making sure the earthing and bonding arrangements are suitable
furthermore the earthing and bonding arrangements if necessary for the protective measure applied
for the safety of the addition or alteration shall be adequate it is also an ideal opportunity to
identify final circuits and any defects that may impact your installation work if the installation
is of an age where lead sheathed or vulcanized India rubber cable was the means of insulation
the suitability and condition of the cable many decades later may be dubious and therefore
ought to be upgraded any disruption to this now brittle aged and weathered cable insulation will
cause further damage encountering this before starting the work pre-warns the client or person
ordering the work and allows an agreement to be made beforehand other pre-installation checks
that should be made include identifying items such as borrowed or shared neutrals regulation
314.4 clearly mentions that taking a neutral conductor from a conveniently located lighting
junction box to supply the upstairs lighting circuit contravenes BS7671 it states that the
wiring of each final circuit shall be electrically separate from that of every other final circuit
so as to prevent the indirect energizing of a final circuit intended to be isolated however
more importantly as the new consumer unit is likely to house RCDs which monitor the current
flow between line and neutral this type of circuit arrangement could lead to nuisance
tripping in fact if the two lighting circuits one upstairs and one downstairs were terminated
into two different RCDs as one is energized the other disconnects and vice versa this is due to
the current flowing out of the line conductor and back down the neutral not being equal additionally
with a dual RCD board best practice would be to terminate the two lighting circuits on different
RCDs thus ensuring that in the event of a fault the entire dwelling isn't plunged into darkness
this would not be possible if borrowed or shared neutrals are present and both lighting circuits
would need to be terminated on the same side speaking of lighting circuits it would also be
common to encounter a lack of circuit protective conductor running to every lighting point an
associated accessories in homes built before 1966 where no such requirement existed thus an
EICR or pre-check can be used to identify where this may be an issue for example if the dwelling
contains Class 1 or metallic light fittings another thing to check would be the levels
of protective conductor current and or earth leakage within the installation this can be
done simply by using an earth leakage clamp meter around both the line and neutral meter tails with
the loads energized this approximate value can provide an indication as to whether RCD nuisance
tripping is likely particularly when the upgraded consumer unit is of the dual RCD type the problem
arises as BS7671 provides a maximum value for the accumulation of protective conductor currents
and or earth leakage downstream of an RCD this maximum is 30 percent of the rating of the RCD
as mentioned in regulation 531.3.2 in length 3. in order to avoid unwanted tripping by protective
conductor currents and or earth leakage currents the accumulation of such currents downstream of
the RCD shall be not more than 30 percent of the rated residual operating current so a 30
milliamp device can have a maximum of 9 milliamps of downstream protective conductor current and or
earth leakage this will would mean a maximum of 18 milliamps across the entire installation for
a dual RCD arrangement with older installations and equipment and appliances the levels of leakage
increase making it quite plausible to readily exceed the maximum value regulation 531.3.2
does however provide a potential solution to this in item 2 where it says to consider the
use of our RCBOs for individual final circuits in residential premises and thankfully a lot of
electricians are selecting this option as their default choice anyway I.E the RCBO consumer unit
in this arrangement the limit of 9 milliamps or 30 is now per individual circuit as with an RCBO
board each circuit has its own RCD thus solving most of the problems associated with protective
conductor currents and or earth leakage within a domestic scenario this regulation also makes
reference to section 314 which relates to the division of circuits in an installation of
particular relevance is regulation 314.1 which states every installation shall be divided it
into circuits as necessary to one avoid danger and minimize inconvenience in the event of a
fault two facilitate safe inspection testing and maintenance three take account of hazards that may
arise from the failure of a single circuit such as a lighting circuit and the particularly relevant
indent 4 reduce the possibility of unwanted tripping of RCDs due to excessive protective
conductor currents not due to a fault this indent relates directly to the idea of measuring earth
leakage so you can tell if the system is likely to trip RCDs with several circuits attached even
when the system is operating normally and it can help you make an informed decision about
whether to go with a split load board or an all RCBO board to be fair although the second
Amendment the 18th edition of BS7671 hasn't yet outrightly banned the use of split load boards
it is getting harder to make them compliant and the general shift of the industry is to the much
more electrically robust all RCBO method knowing this type of information beforehand can ensures
that the correct equipment is sourced from the wholesaler or distributor in the first instance
thus saving time and money and provides your client with a better level of service overall
so even though it may not be a requirement to carry out an EICR before replacing a consumer
unit it's a very very good idea to do so if you'd like some more hints tips and regulations
on consumer unit replacement then check out our free training package to help you with your CPD
by clicking the link in the description below or to see the reasons why you might want to
replace a consumer unit check out this video right here thank you very much for watching