Fitting an Extractor Fan
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When installing an extractor fan in a bathroom, it is important to remember that under the wiring regulations a room containing a bath or shower is considered to be a special location and certain conditions apply. These conditions apply because of the increased risk of electric shock due bare wet skin which results in a reduction in body resistance and the increased possibility of large areas of the body coming into contact with earth potential.
The new wiring regulations introduced in 2008, the 17th edition, has changed the conditions set out in the 16th edition. For example, RCDs are required for all circuits in locations that contain a bath or shower. The requirements for local supplementary bonding have been relaxed if certain conditions are met.
The points relating to safety are discussed below:
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Unpacking the replacement fan |
Old fan with cover removed |
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Testing for voltage |
Removing the broken fan |
Zones within a bathroom
Rooms containing a bath or shower are divided into zones with different conditions being applied to each zone. The new zones are Zone 0, Zone 1 and Zone 2. Zone 3 no longer applies. This is partly due to the introduction of RCDs and partly to help bring the UK in line with the electrical standards in Europe. These zones are an important factor when extractor fans are being considered as they indicate which types of equipment are permitted, where it is appropriate to position them and if any additional safety measures should be taken.
Zone 0 is inside the bath tub or shower basin
Zone 1 is the space above the bath tub or shower basin up to a height of 2.25m
Zone 2 is the space that extends horizontally from the edge of the bath tub or shower basin for 0.6m to a height of 2.25m
The space under the bath is considered to be outside the zones if a tool is required to gain access e.g. by having to use a screwdriver to remove a bath panel.
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Taking an R1 + R2 reading |
Testing the circuit before taking a Zs reading |
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Feeding the cable through |
Replacing the fan in the ceiling |
Permitted protective measures in a bathroom
The protective measures permitted in a bathroom or shower room vary depending on the zone where the equipment is installed. Generally the measures allowed are ADS; Automatic Disconnection of Supply (this used to be called EEBAD under the 16th edition wiring regulations), extra low voltage provided by SELV, Separate Extra-low Voltage or PELV, Protected Extra-low Voltage. These circuits however must be protected by an RCD, Residual Current Device. In addition, depending upon the circumstances local supplementary bonding may be required.
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New fan without cover and motion sensor in place |
New extractor fan installed and tested |
Selection of equipment
Zone 0 The external influence is IPX7 no accessories or switchgear to be installed
Zone 1 The external influence is IPX4 only SELV circuits; Extra low voltage via safety source such as a transformer installed outside the zone
Zone 2 The external influence is IPX4 or IPX5 if water jets are used. No switchgear or accessories in this zone unless SELV with the safety source outside the zone or a shaver socket that complies with BS EN 61558-2-5
Under the bath, if a tool is needed to gain access, is considered to be outside the zones
It must be remembered that when selecting the extractor fan for the bathroom, the manufacturer will indicate on the packaging if the fan is suitable for inclusion within a a particular zone.
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