Electrical connections between motor vehicles and trailers

Electrical connections shall be designed to prevent:
- Ingress of moisture and dirt; the connected parts shall have a protection degree of at least IP
54 in accordance with IEC 60529;
- Accidental disconnection; connectors shall fulfil the requirements given in clause 5.6 of
ISO 4091:2003.

Requirements of are deemed to be met:
- for connectors standardized for specific purposes according to ISO 12098:20041, ISO
7638:20031, EN 15207:20141 or ISO 25981:20081
- where the electrical connections are part of an automatic coupling system (see ECE
Regulation No.552).

Electrical connections for other purposes concerning the proper functioning of the vehicles or their
equipment may be used provided they comply with the requirements of


The nominal voltage of the electrical system shall not exceed 25V A.C. or 60V D.C.
Higher voltages are allowed in galvanically isolated parts of the electrical system provided those parts
are not located within a perimeter of at least 0.5 metres from the outside of the load compartment or
Additionally systems working on a voltage higher than 1000V A.C. or 1500V D.C. shall be integrated
in an enclosed housing.
If Xenon lights are used only those having integrated starters are allowed.
1 ISO 4009, referred to in this standard, need not be applied.
2 ECE Regulation No. 55 (Uniform provisions concerning the approval of mechanical coupling components of
combinations of vehicles).

Battery master switch

A switch for breaking the electrical circuits shall be placed as close to the battery as practicable. If a
single pole switch is used it shall be placed in the supply lead and not in the earth lead.

A control device to facilitate the disconnecting and reconnecting functions of the switch shall be
installed in the driver's cab. It shall be readily accessible to the driver and be distinctively marked. It
shall be protected against inadvertent operation by either adding a protective cover, by using a dual
movement control device or by other suitable means. Additional control devices may be installed
provided they are distinctively marked and protected against inadvertent operation. If the control
device(s) are electrically operated, the circuits of the control device(s) are subject to the requirements

The switch shall break the circuits within 10 seconds after activation of the control device.

The switch shall have a casing with protection degree IP 65 in accordance with IEC Standard 60529.

The cable connections on the switch shall have protection degree IP 54 in accordance with IEC 60529.
However, this does not apply if these connections are contained in a housing which may be the battery
box. In this case it is sufficient to insulate the connections against short circuits, for example with a
rubber cap.

Permanently energized circuits

(a) Those parts of the electrical installation including the leads which shall remain energized
when the battery master switch is open, shall be suitable for use in hazardous areas. Such
equipment shall meet the general requirements of IEC 60079, parts 0 and 143 and the
additional requirements applicable from IEC 60079, parts 1, 2, 5, 6, 7, 11, 15 or 18;
(b) For the application of IEC 60079 part 143, the following classification shall be used:
Permanently energized electrical equipment including the leads which is not subject to and shall meet the requirements for Zone 1 for electrical equipment in general
or meet the requirements for Zone 2 for electrical equipment situated in the driver's cab. The
requirements for explosion group IIC, temperature class T6 shall be met.
However, for permanently energized electrical equipment installed in an environment where
the temperature caused by non-electrical equipment situated in that environment exceeds
the T6 temperature limit, the temperature classification of the permanently energized
electrical equipment shall be at least that of the T4 temperature class.
(c) The supply leads for permanently energised equipment shall either comply with the
provisions of IEC 60079, part 7 ("Increased safety") and be protected by a fuse or automatic
circuit breaker placed as close to the source of power as practicable or, in the case of
"intrinsically safe equipment", they shall be protected by a safety barrier placed as close to
the source of power as practicable.

Bypass connections to the battery master switch for electrical equipment which must remain energized
when the battery master switch is open shall be protected against overheating by suitable means, such
as a fuse, a circuit breaker or a safety barrier (current limiter).
3 The requirements of IEC 60079 part 14 do not take precedence over the requirement of this Part.

Braking equipment

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