Bathrooms: volumes 0, 1 and 2 explained simply

The RGIE divides the space around the bath and the shower into volumes, with rules that get stricter the closer you get to the water. This is chapter 7.1 of Book 1, which applies to locations permanently containing a bath or shower, to locations where mobile applications are installed, for example a mobile shower on a worksite, and to modifications and extensions of those locations. Here is the logic, without the jargon.

Why volumes

In a bathroom, the skin is wet, sometimes immersed: table 7.3 of Book 1 classifies the condition of the human body as BB3 (skin immersed) in volumes 0 and 1, and BB2 (wet skin) elsewhere. Book 1 therefore grades the requirements according to how close you are to the bath or shower: the closer to the water, the less equipment is allowed. On top of this come two measures for the whole location: circuits protected by a high or very high sensitivity RCD, that is 30 mA at most according to section 2.6.4, except SELV, electrical separation or safety installations (subsection 7.1.4.3), and supplementary equipotential bonding (subsection 7.1.4.4).

The three volumes, simply

The volumes are arranged around the bath, or around each fixed water outlet for a shower. Subsection 7.1.3.2 sets their limits; here is the gist:

Outside the volumes, the rest of the location has its own rules. According to subsection 7.1.1.1, it runs from the finished floor up to 3 m high, or up to the ceiling if lower, and up to 4 m from the fixed water outlets, within fixed vertical walls at least 2.25 m high or meeting a ceiling or a false ceiling that is not perforated and cannot be removed without a tool. Watch out for the special cases: a shower without a tray, a bath whose bottom is not at floor level, a fixed wall or a door all change the layout (subsections 7.1.3.1 to 7.1.3.4). A shower with several fixed water outlets follows the most severe combination of volumes. When in doubt, measure and refer to the figures in Book 1.

What is allowed in each volume

• Volume 0: only fixed machines or appliances, suitable for this volume according to the manufacturer’s instructions, permanently connected and supplied at SELV, with the SELV source outside volumes 0 and 1. No socket, no control device except one that is part of those appliances, at SELV. The SELV voltage is limited to 12 V AC (table 7.2), or 6 V if the equipment is IP00 (table 7.1).
• Volume 1: fixed appliances and sockets at SELV, control devices at SELV, always with the source outside volumes 0 and 1; and low-voltage fixed appliances if they are suitable for this volume according to the manufacturer and permanently connected, not through a socket. Sockets and control devices that are part of those low-voltage fixed appliances are allowed provided they are supplied at SELV, with the source outside volumes 0 and 1.
• Volume 2: fixed appliances, permanently connected or through a socket; SELV sockets; low-voltage sockets protected either by a very high sensitivity RCD or each individually by an isolating transformer of 100 W at most; control devices at SELV or low voltage.
• Outside the volumes: sockets are possible, on the protected circuits of the location. Distribution boards are prohibited in volumes 0, 1 and 2.

The degree of protection against water follows from table 7.3: AD7 in volume 0, AD4 at least in volume 1, AD4 in volume 2 and AD2 outside the volumes, which according to table 5.4 corresponds to IPX7, IPX4 and IPX1. A note to table 7.3, attached to volume 2 and to the area outside the volumes, sets the permitted degree of protection of socket outlets supplied at low voltage at IPXX: no particular IP requirement for those sockets. When a piece of equipment straddles several areas, the most stringent requirements of table 7.3 apply (subsection 7.1.5.1).

The supplementary equipotential bonding

According to subsection 7.1.4.4, it locally connects all exposed conductive parts of electrical equipment and all simultaneously accessible extraneous conductive parts in the location. Figure 7.1 lists the metal waste pipe, metal water and central heating pipes, the metal bath, metal door frames and the metal radiator. Excluded are the exposed parts of SELV equipment, non-conductive pipes such as plastic, radiators supplied through such pipes and the enclosures of class II equipment. The aim: no dangerous voltage between two things you touch at the same time. According to subsection 5.4.4.2, the cross-section of the conductors is at least half that of the protective conductor connected to the exposed conductive part, the earthing conductor excluded, when the bonding connects that part to an extraneous conductive part, or the smallest cross-section of the protective conductors connected when it links exposed parts of different appliances; and in any case no less than 2.5 mm² when the conductors are mechanically protected, 4 mm² otherwise. The general principle is explained in our article on earthing.

Three concrete cases

• The spotlight above the shower. In volume 1, a luminaire is only allowed at SELV with the source outside volumes 0 and 1, or at low voltage if it is suitable for this volume according to the manufacturer and permanently connected. Above the height of volume 1, you are outside the volumes.
• The shaver socket near the washbasin. It all depends on the volume the socket falls in: no socket in volume 0, only a SELV socket in volume 1, and in volume 2 a low-voltage socket on its own isolating transformer of 100 W at most or behind a very high sensitivity RCD.
• The heated towel rail. A fixed appliance, allowed in volume 2, and in volume 1 at low voltage only if it is suitable for this volume and permanently connected. Its circuit is protected by a high or very high sensitivity RCD, and its exposed parts are included in the equipotential bonding unless it is class II. Placing it outside the volumes makes things simpler.

Points to check

• Measuring from memory. Volume boundaries are measured on site, not judged by eye. A socket fitted too close is hard to move once the tiling is done.
• Forgetting the walk-in shower. Without a tray, volume 0 starts from the floor over 1.20 m around each fixed water outlet, and volume 1 rises over the same radius to at least 2.25 m, unless a fixed wall limits it.
• Neglecting the equipotential bonding because everything is concealed. It covers all simultaneously accessible exposed and extraneous conductive parts; only the exclusions in subsection 7.1.4.4 escape it.
• A file silent on the bathroom. The single-line diagram shows the type and characteristics of the RCDs (subsection 3.1.2.2), and the position plan the location of sockets, lighting points and fixed appliances (subsection 3.1.2.3).

When it is time to document the room, the file may as well keep up: in Amperio, each circuit is checked against the RGIE as you enter it, and a missing 30 mA RCD is flagged at the exact spot on the diagram. On the position plan, each element, dictated or placed by hand, goes in the right room.

This article is informative. It replaces neither the RGIE (Book 1) nor the advice of your inspection body.