"17th Edition Consumer Unit" - The Most Misunderstood Term in Home Improvement

The term '17th Edition Consumer Unit' is now oneoffer greater compliance than others by enabling
of the most commonly used and misunderstoodbetter 'Division of Installation or separation of
in the UK Electrical vernacular. Through lack ofcircuits, which prevents 'nuisance tripping'.
industry conformity the phrase has come toTo clarify the situation the UK manufacturer
mean a fuse board supplied with two RCDs. BUT:Wylex has introduced a '5 star' system, akin to
This does not necessarily mean that it abides bythat used by hotels, to grade compliance.
17th Edition Regulations and certainly does notIronically, the very design which has over the last
mean that other designs are not 17th Editiontwo years been marketed as a '17th Edition
compliant.Consumer Unit', is the one which scores lowest
Let us first remind ourselves of what the 17thwith only 2 stars.
Edition Regulations actually mean in terms ofThe Dual RCD board was originally considered the
circuit protcetion: The 17th Ed Regulations state,best way to [ cheaply ] satisfy the 17th Ed Regs,
quite simply that all circuits must be protectedwhich is why it became known as a '17th Edition
against earth leakage, which means in layman'sConsumer Unit'. But this configuration does not
terms that individuals are protected againstallow for any separation of circuits and therefore
electric shock.crucially, does not allow for a separate smoke
This may be done by using an RCD (Residualalarm circuit and makes no provision for nuisance
Current Device), which protects a bank of circuitstripping.
against earth leakage simultaneously or an RCBOUnder the Wylex system the only type of
(Residual Current Breaker with Overloadconsumer unit which scores five stars is the older
protection), which protects an individual circuit.type Main Switch consumer unit as it allows for
Every installation is different depending upon afull loading of RCBOs therefore providing complete
number of variables including the number ofindependent circuit protection against earth
circuits, the types of device being protected onleakage. High Integrity and Split Load consumer
each circuit, the loads on individual circuits and ofunits both score 4 stars as they allow for a
course the customer's budget. For this reason allcertain amount but not complete, circuit division.
consumer units are configurable upon installationIn summary, a consumer unit cannot inherently be
and may therefore protect against earth leakage'17th Edition' and this has become a misleading if
using a combination of RCDs, RCBOs or both.not dangerous misnomer. Only when it is installed
In general each of the four generic designs of UKand loaded according to the 17th Ed Regs and
fuse board; Main Switch, Split Load, High Integrityhaving taken into account the specific installation
and Dual RCD all meet the requirements of thevariables can a consumer unit be considered '17th
17th Edition. However, depending on the installationEdition'.
variables it becomes apparent that some designs