Electrical safety in the construction of showers and bathrooms

ovariesracialUrban and Civil

Nov 25, 2013 (3 years and 8 months ago)

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This information bulletin alerts Licenced Electrical Workers and Contractors to the requirements of Clause
5.6.2.5 Showers and Bathrooms in AS/NZS 3000:2007.

Any conductive reinforcing within a concrete floor or wall forming part of a shower or bathroom

shall be
bonded to the earthing system of the electrical installation to avoid any potential differences that may occur
between conductive piping (including taps, drains etc) connected to or in contact with the electrical installation
earthing system, and

the concrete floor or wall.

An equipotential bonding conductor shall be connected between the reinforcing material and any part of the
earthing system within the room.

The 2007 Standard introduced a number of changes, and this one is among the most

groun
d
-
breaking. This requirement has been enforced for many years overseas, and has been included to
reduce the increasing number of electric shocks that are recorded each year.

Whilst installing the bonding conductor does not alleviate the cause of the shock
, it eliminates the voltage
potential. As with all cases of equipotential bonding, it works by maintaining the conductive paths at the same
potential.

The main causes for shocks in bathrooms are:

(i)

MEN Shocks: A high impedance in the neutral of the cons
umers mains or distribution system causes the
neutral current to flow through the MEN connection to earth. This causes a voltage rise on the water
pipes, and a voltage potential between the taps and the wet bathroom floor which contains the
reinforcing mes
h.

(ii)

Induced Voltages: An existing cable installed in the concrete induces a voltage onto the reinforcing
mesh, causing a voltage potential between the wet bathroom floor and the taps.

(iii)

Damaged Cable: An existing, damaged cable installed in the con
crete short circuits to the reinforcing
mesh, causing a voltage potential between the wet bathroom floor and the taps.

Reproduced with permission from the Regulation Roundup


Office of the Technical Regulator South Australia
Issue 20 October 2007.



BULLETIN

Electrical safety in the construction of
showers and bathrooms








For further inf
ormation please contact NT WorkS
afe on 1800 019 115 or go to
worksafe.nt.gov.au