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equipment.

RCD

RCD’s are seen by some as a magic device that will cure all sins. This is not so, RCD’s only protect
from earth faults, they will not protect against short circuits. If a sign is not earthed it is still possible for
it to become live and remain so even if protected by an RCD.

RCD’s function by detecting the difference in currents through the live and neutral conductors. During a
short circuit the currents increase dramatically but remain correlated in both conductors, so the RCD will
not trip.

RCD’s come in several ratings, the only ones considered safe for direct contact with a live part is are
10mA and 30mA devices. 10mA devices are rare. A lot of newer distribution boards come with RCD’s
built in, sometimes these are 30mA, however commonly they are 100mA devices. A 100mA device is
not sufficient to prevent a dangerous shock – it may not kill but will cause muscle contractions that could
result in secondary injuries, e.g. falling from height.

Do not be fooled into thinking it is safe to work on a sign live because it is protected by an RCD.

Conductor Colours

The colour of non-flexible cable conductors are in the process of being changed. The previous standard
of using Red as live and Black as neutral is being phased out, with the colours of Brown as live and Blue
as Neutral being introduced (the same colours as currently used in flexible cables). Existing installations
will not have to be altered to suit the new colours, however you will start to see the new colours on new
installations. All new installations after 31 March 2006 will have to use the new colour identification.

The colour of the earth remains unchanged at green/yellow.

Electrically Competent Persons

Please note that we are developing an electrical competency course “in house”, utilising the skills of our
specialists who are qualified to Comp’Ex 7/8, IEE 16th Edition and C&G 2391 standards. The content
and means of testing competency are currently being independently assessed.

AGAIN, IF IN DOUBT, NEVER CARRY OUT ANY ELECTRICAL

WORK – ASK FOR ASSISTANCE, REGARDLESS OF COST!!

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Environmental Bulletin No 2 Electrical Work.doc