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Home / Construction / Regulation / Electrical safety standards for bathrooms and toilets (español – italiano – français)
What are the rules for installing electrical appliances in bathrooms and shower rooms?
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The electrical circuits supplying water to a room must be protected by a 30 mA differential switch. But that is not enough. But this is not enough. Regulatory distances must be respected.
Summary of the article (5 minutes reading):
- Which premises are affected by the regulations?
- Section 701 of BS 7671:2018: 4 volumes to be respected
- Taking into account the fixed walls of baths and/or showers in the delimitation of volumes
- What is allowed depending on the equipment, the insulation classes of the devices and the protection ratings (IP)
NF C15-100 standard (for FRANCE): the different volumes of a bathroom or shower (with bathtub, shower or spa)
The NFC 15-100 standard is the reference that regulates low-voltage electrical installations in residential and commercial buildings in France. As part of the protection of the electrical installation and people, the standard defines 4 volumes for bathrooms and showers. Its objective is to define what is authorized in what volume (plug, switch, radiator, heated towel rail, lighting, tumble dryer, etc.). The volumes are defined from the following water points: bathtub, shower (with tray, cabin, dressing room), spa.
Regulatory volumes (NF C 15-100 part 7-701):
- Volume 0:
- The volume created by the inside of the bathtub or the shape / height of the shower tray (if there is a shower tray).
- For walk-in showers, it corresponds to the shape of the 10 cm raised shower tray. The shape is defined by volume 1.
- The hidden volume corresponds to the space under the bathtub or under the shower tray. It is not included in volume 0 although the security rules are the same.
- Volume 1:
- From the outer edges of the bathtub and rising to a height of 225 cm (from the bottom of the bathtub).
- For showers with a tray, the volume rises from the shower tray to a height of 225 cm or to the height of the shower head, if the latter is above 225 cm.
- For walk-in showers (without a shower tray), draw a circle with a radius of 1.2 m that will rise 225 cm or the height of the shower head if it is above 225 cm. The starting point of the radius of the circle follows the following rules:
- in the case of a shower head: the center of the shower head.
- in the case of the hand shower: the connection point of the hose (at the mixing valve)
- in the case of a “rain” shower: all points that make up the outer edge of the waterfall
- For showers with horizontal jets, volume 1 ends on the next wall that blocks the water jet.
- In the case of multiple sprinklers, we take all the volumes defined by each sprinkler.
- Volume 2:
- Volume from 0 to 60 cm around volume 0 and 1, up to a height of 225 cm (same height as volume 1).
- Outside Volume: the rest of the bath volume.

Bathtub and shower volumes with shower tray nf c 15100 for bathroom


The NF C 15-100 standard largely complies with CENELEC’s European standard HD384 and IEC’s international standard 60364.
- Spain: REBT standard ITC-BT-27 (Locales que contienen una bañera o ducha)
- Italy: IEC 64-8 standard
- UK: BS 7671 standard
- Portugal: RIEBT standard
- Switzerland: NIBT-NIN
- etc.
Taking into account the fixed walls of bathtubs and / or showers in the delimitation of the volumes



What is authorized according to the equipment, insulation classes and protection indexes.


On volume 0 (IPX7):
- It is forbidden to install any electrical equipment except for class 3 IPX7 lights powered with SELV (very low voltage) 12 Volts max. alternative
- the same in the hidden volume
- a maximum 12V (alternating current) class 3 SELV (Very Low Voltage) lighting device with transformer, or 30V direct current
- Degrees of protection authorized: IPX4 or IPX5 (if they are horizontal jets)
- Class 1 storage water heater installed horizontally (tolerated if placed as high as possible)
- instantaneous water heater (class 1) if it is powered directly by a cable without a connection box.
- a pipeline to supply the authorized devices in these volumes.
- Note: the power supply must be installed outside of volumes 0, 1 or 2
- storage water heater (cumulus) (class 1)
- instant water heater (class 1)
- Authorized lighting in volume 1 + 230V class 2 lighting protected by differential circuit breaker 30 mA max. The transformer can be installed on the drywall (if this serves as a ceiling). Class 2 lighting.
- Class 2 electric heater (radiators)
- razor plugs (with 50VA max isolation transformer)
- Degrees of protection authorized: IPX4 or IPX5 (if they are horizontal jets)
- Note: the power supply must be installed outside of volumes 0, 1 or 2
- lighting class 1
- grounded outlet (prohibited on the floor, above a sink)
- washing machine (class 1), tumble dryer (class 1)
- Class 1 electric heater (radiators)
- isolation transformer
- connection box
- IPX4: projection of water from all directions
- IPX5: projection against water jets with lance from any direction
- IPX7: projection against the effects of temporary immersion.
- Class 1: grounding for all metal parts of the device (equipotential grounding). The device must have a grounded plug that must be connected. There is no danger for people if the electrical installation of the house works normally (differential circuit breaker, earth).
- Class 2: double insulation (or reinforced insulation) without ground. This means that the plug of the device does not need a ground wire as the device is double insulated (metal parts are not accessible). There is no danger to humans.
- Class 3: Class 2 insulation AND very low voltage transformer (SELV galvanic isolation) mandatory. The device works with a very low safety voltage (maximum 50 V in alternating current).
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