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Ventilation Building Regulations
All domestic ventilation installation are required to meet the following regulations by law. Building regulations document F can be downloaded here.The below extract applies to Ventilation rates for Bathrooms, Kitchens Utility rooms etc:
IEE Regulations for Bathrooms
Failure to follow regulations relating to electricty in the bathroom can be fatal
The previous IEE 16th Edition identified zones within the bathroom to illustrate what type of electrics in the bathroom can be used or installed, and these have been updated in the 17th Edition. These zones take into account windows, doors, walls ceilings and partitions, assessing the level of risk in each zone, with specific requirements governing the type of equipment deemed safe to be used in each. Zones 0-2 are considered the wettest, and the former zone 3 is no longer defined.
Applies to inside the bath or shower. Here electrical products must be low voltage (a maximum of 12V) and be IPX7, i.e. can withstand total accidental immersion.
Applies to the area around the bath or shower up to a height of 2.25m above the floor and at a radius of 1.2m from the water outlet. A minimum rating of IPX4 is required. If the fitting is 240V a 30mA residual current device (RCD) must also be used to protect the circuit in this zone, i.e. SELV with the transformer located beyond zone 2.
Applies to the area beyond Zones 0 and 1, 0.6m horizontally and up to 2.25m vertically, including any recessed window with a sill next to the bath. This area requires electrical products to be IPX4 or better, or SELV with the transformer located beyond zone 2. It is advisable to consider the area around a wash basin, within a 60cm radius of any tap as Zone 2.
These are classed as anywhere outside Zones 0, 1 and 2 (subject to specific limits) and where no water jet is likely to be used. No IP rating is required here unless water jets are used for cleaning purposes in Zones 1, 2 and "Outside Zones", in which case a minimum IPX5 must be used. Portable equipment is allowed in Outside Zones providing they are located where their flex length prevents them from being used in Zone 2, and they must be plugged in outside the bathroom, with the socket far enough away to ensure the appliance cannot be used inside zone 3. Any space under the bath is considered out of scope, so long as it cannot be accessed without using tools such as a screwdriver.
PELV and SELV
Electrical products may also be identified as as PELV - Protective Extra-Low Voltage, low voltage but connected to earth, or SELV - Separated Extra-Low Voltage, low voltage but with output isolated from the input. SELV products can be used in any zone in the bathroom providing the source, such as the transformer, is located beyond Zone 2.
It is good practice to use CE & Safety Certified Products as they are tested according to all appropriate electrical standards, with factory inspection and ongoing product surveillance and specific test programmes related to their performance in damp and wet environments. For installations in the bathroom electricians should look for the UK's two most common safety certification marks - the ASTA Diamond Mark and the BEAB Approved Mark.