ELECTRICAL
TECHNICAL
Cabin fever
The increased risk of electrical shock associated with sauna cabins
means that they are treated as special locations. Graham Wretham
looks into the rules and regulations governing their installation.
i
NOTE
This topic considers
the electrical installation
requirements for sauna
cabins erected on site. That is,
the cabin being erected in a
specific location or room. The
topic also considers electrical
installation requirements for
the room in which the sauna
is to be located.
R
ooms and cabins
containing sauna
heaters are considered
as a ‘special location’
within the IET Wiring Regulations,
BS 7671 because of the increased
electric shock risk associated with,
amongst other things, extreme
high temperatures with high
humidity, lack of clothing and
reduced skin resistance. Clothing,
particularly shoes, can greatly
increase the total body resistance
of an individual and therefore
reduce the risk of electric shock.
Zones
The room or cabin is divided
into three temperature zones
that provide an indication of
what electrical equipment
can, or cannot, be installed in
that particular area. Moreover,
any electrical equipment and
enclosures shall have a
minimum degree
of protection
of IPX4 (splash proof) or, if the
room is to be hosed down as
is the case for many sauna
cabins within sports centres, the
equipment and enclosures would
need to have a minimum degree
of protection of IPX5 (jet proof).
• Zone 1: Only the sauna heater
and equipment belonging
to the sauna heater shall be
installed.
• Zone 2: There are no special
requirements concerning heat
resistance of equipment.
• Zone 3: The equipment
shall withstand a minimum
temperature of 125°C, and the
insulation and sheaths of cables
shall withstand a minimum
temperature of 170°C. High
Temperature Flexible (HTF)
cables should therefore be
specified for cable installations
within Zone 3.
Wiring systems
Understandably, any wiring
installed within the room
containing the sauna heater is
likely to be subject to extremely
high temperatures. It is, therefore,
recommended that wiring
systems should preferably be
installed outside the zones
– i.e. outside the room. If the
installation of wiring within the
sauna room cannot be avoided,
the wiring system must be heat
resisting.
Similarly, if the wiring system
selected incorporates metallic
conduits, they must be installed
in a position where they are not
accessible to whoever is using
the sauna. Moreover, if these
metal conduits are connected
to metallic accessories such as
a Class I light fitting, the metallic
light fitting should also not be
accessible to the sauna users.
Again, this will generally mean
that the metallic conduit system
and any associated metallic
accessories are installed outside
of the room containing the
sauna heater.
Electrical equipment
As previously stated, the
temperature and humidity
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conditions within the sauna
room are extremely harsh.
It is therefore necessary to
ensure that any switchgear or
control gear required for the
operation of the sauna heater
is installed in accordance with
the manufacturer’s instructions.
Other electrical equipment
may be installed in Zone 2,
but the installer should follow
manufacturer’s instructions
carefully after seeking assurances
that such equipment is suitable
for the location.
Other electrical equipment
such as luminaires and light
switches should be installed
outside the room containing
the sauna heater. Socket outlets
are also not allowed within the
sauna room.
The sauna heater
Sauna heater appliances should
comply with BS EN 60335-2-53
and be installed in accordance
with the manufacturer’s
instructions.
In order to withstand the harsh
environment, heating elements
incorporated within the sauna
heater are likely to be metal
sheathed. Unless these elements
have additional waterproof seals,
they are likely to absorb some
moisture and could cause small
earth leakage currents to flow,
which could cause a 30mA
Residual Current Device (RCD) to
operate if one is installed in the
heater circuit. Accordingly, RCD
protection need not be provided
for the sauna heater unless the
manufacturer requires it.
Protection against
electric shock
Protection against electric shock
is treated a little differently in
special locations of high risk such
as sauna rooms, swimming pools
and bathrooms. The measures
are more geared towards
protecting against the risk of
electric shock by not allowing
any electrical equipment into the
specific sauna location that does
ELEVATION
Zone 3
not form part of the sauna heater
itself. It is strongly recommended
that any lighting, luminaires and
switches, and socket outlets etc
be located outside the room
containing the sauna.
It should be noted that
many sauna rooms are located
within sports complexes and
are likely to be adjacent to a
swimming pool, which has its
own zonal requirements and
conditions. It may be that the
sauna room opens out into Zone
1 or Zone 2 of a swimming pool.
This location would then prevent
socket outlets being situated
near the sauna room.
Any electrical circuit for lighting
and power, other than the sauna
heater circuit itself, would need to
provide additional protection by
the use of a 30mA RCD.
Where SELV is used, usually
for decorative down-lighters,
protection against electric shock
must be provided by basic
insulation and barriers and
enclosures to IP2X, which means
inside an enclosure that prevents
a finger from touching a live part.
Other basic protection
measures of using obstacles
or placing out of reach are not
The author
Graham Wretham is
Managing Director of Redford
Charles Ltd, an electrical
training and consultancy
company in Kent.
Previously the NICEIC
Inspecting Engineer for Kent,
Graham was later promoted to
Senior Engineer and was also
the NICEIC’s representative
on various external and
international technical
panels. Graham gained
further promotion to NICEIC
Operations Manager and then,
following a restructure, to
Operations Director.
Graham left the NICEIC in
2005 to start his own electrical
and consultancy business,
Redford Charles Ltd, which
has become one of the leading
electrical training companies
in the south east and works for
a number of blue chip clients.
allowed. Nor are fault protection
measures of non-conducting
location or earth-free local
equipotential bonding. n
Zone 1
TO SUM UP
0.5m
Zone 2
1m
› Rooms and cabins containing sauna heaters are
considered as a ‘special location’ within the IET Wiring
Regulations, BS 7671 because of the increased electric
shock risk.
Electrical
connection
enclosure
› The room is divided into three temperature zones.
› Any electrical equipment and enclosures must have
a minimum degree of protection of IPX4 (splash proof)
or IPX5 (jet proof).
PLAN
› Wiring systems should be installed outside the zones
and preferably be outside the sauna room.
Zone 2 and Zone 3
0.5m
› Socket outlets are not allowed within the sauna room.
Zone 1
› Any electrical circuit for lighting and power, other than
the sauna heater circuit itself, would need to provide
additional protection by the use of 30mA RCD.
› RCD protection need not be provided for the sauna
heater unless the manufacturer recommends it.
0.5m
Thermal
insulation
› If the room containing the sauna heater opens out onto
a swimming pool are, the additional requirements for
swimming pools may apply.
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