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Crimping of flexible cord conductors

PG over 3 years ago

Like most of us, I often crimp flne strand conductors, especially for screw terminals but do not do this for domestic lamp holders and roses etc.

I thought that I would check Section 526 (Electrical Connections) of the Regs but did't find a clear statement of requirements for crimped ends.

I was particularly unsure of what 526.9.1 was specifying for fine wire conductors "conductor ends shall be suitably treated".

Any guidance or comment would be appreciated.

Regards

Parents

0 gkenyon over 3 years ago
I wish I could say "simples" but it's definitely NOT.

The answer to the OP is, it depends on either the product standard for the particular accessory or terminal, the manufacturer's instructions, or both.

There are 4 types of conductor in common use for power cables:
Class 1 (solid) – with a single strand – usually used for some sheathed fixed wiring cables up to 2.5 mm².

Class 2 (stranded) – a minimum of 7 strands – usually used for unsheathed fixed wiring cables, and some sheathed fixed wiring cables up to 2.5 mm², and all sheathed fixed wiring cables of 4 mm² and greater.

Class 5 (flexible) – sometimes called finely stranded - flexible cables and internal appliance wiring. Also used in places where vibration is greater (e.g. main bonding in mobile and transportable units, and may be used in caravans and mobile and transportable units)

Class 6 (extra flexible) – sometimes called extra-finely stranded - may be used in very high vibration environments or equipment.

Examples of where the standard specifies the types and sizes of cables that do not require special treatment include:

BS EN 61184 for lampholders requires the terminals for lampholders sold in the UK to be suitable for 0.5 mm² and 0.75 mm² flexible conductors for cordgrip lampholders, and 0.5 mm² to 1.0 mm² flexible conductors for threaded-entry lampholders. (in the EU, up top 2.5 mm2 flexible are permitted).

Batten lampholders are only required to be suitable for 0.5 mm² to 2.5 mm² solid (class 1) conductors – so check with the manufacturer’s instructions before terminating stranded conductors in them without ferrules !

BS 1363-2 requires portable socket-outlets with screw terminals to be suitable for connection of a single 1 mm² or 1.5 mm² flexible conductor. Therefore, if using 0.75 mm² flexible cable, at least a “doubling back” is required to obtain a suitable csa for the terminal.

BS 1363-2 requires fixed socket-outlet line and neutral screw terminals to be suitable for connection of 1, 2 or 3 no. 2.5 mm² solid (class 1) or stranded (class 2) conductors, or 2 no. 4mm² conductors. Screw terminals for protective conductors shall be suitable for connection of 1, 2 or 3 no. 1.5 mm² or 2.5 mm² solid (class 1) or stranded (class 2) conductors, or 2 no. 4mm² conductors.

BS 1363-4 requires incoming screw terminals to be suitable for the same size/no. of conductors as socket-outlets.

Outgoing terminals (L, N and PE) must be suitable for connection of flexible (class 5) conductors in the range 0.5 mm² to 1.5 mm², or one conductor of solid (class 1) or stranded (class 2) with csa 1.5 mm² or 2.5 mm².

Examples of where manufacturer’s data or instructions are the only clue as to whether special preparation is required are:

Fixed socket-outlets to BS 1363-2 or connection units to BS 1363-4 with screwless terminals. The manufacturer may choose whether they are suitable for flexible (class 5) only, or solid + stranded (Class 1 + 2) only, or all 3 (class 1, 2 and 5).

Some crimps – especially the common red, blue & yellow – may not be suitable for solid (class 1) or stranded (class 2) conductors. Usually, if suitable for solid or stranded conductors, the crimp will have ridges around the inside

Some screwless connectors are only suitable for certain types of conductor – e.g. common screwless connectors without levers might only be suitable for solid or stranded (class 1 and 2) conductors.
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0 gkenyon over 3 years ago
I wish I could say "simples" but it's definitely NOT.

The answer to the OP is, it depends on either the product standard for the particular accessory or terminal, the manufacturer's instructions, or both.

There are 4 types of conductor in common use for power cables:
Class 1 (solid) – with a single strand – usually used for some sheathed fixed wiring cables up to 2.5 mm².

Class 2 (stranded) – a minimum of 7 strands – usually used for unsheathed fixed wiring cables, and some sheathed fixed wiring cables up to 2.5 mm², and all sheathed fixed wiring cables of 4 mm² and greater.

Class 5 (flexible) – sometimes called finely stranded - flexible cables and internal appliance wiring. Also used in places where vibration is greater (e.g. main bonding in mobile and transportable units, and may be used in caravans and mobile and transportable units)

Class 6 (extra flexible) – sometimes called extra-finely stranded - may be used in very high vibration environments or equipment.

Examples of where the standard specifies the types and sizes of cables that do not require special treatment include:

BS EN 61184 for lampholders requires the terminals for lampholders sold in the UK to be suitable for 0.5 mm² and 0.75 mm² flexible conductors for cordgrip lampholders, and 0.5 mm² to 1.0 mm² flexible conductors for threaded-entry lampholders. (in the EU, up top 2.5 mm2 flexible are permitted).

Batten lampholders are only required to be suitable for 0.5 mm² to 2.5 mm² solid (class 1) conductors – so check with the manufacturer’s instructions before terminating stranded conductors in them without ferrules !

BS 1363-2 requires portable socket-outlets with screw terminals to be suitable for connection of a single 1 mm² or 1.5 mm² flexible conductor. Therefore, if using 0.75 mm² flexible cable, at least a “doubling back” is required to obtain a suitable csa for the terminal.

BS 1363-2 requires fixed socket-outlet line and neutral screw terminals to be suitable for connection of 1, 2 or 3 no. 2.5 mm² solid (class 1) or stranded (class 2) conductors, or 2 no. 4mm² conductors. Screw terminals for protective conductors shall be suitable for connection of 1, 2 or 3 no. 1.5 mm² or 2.5 mm² solid (class 1) or stranded (class 2) conductors, or 2 no. 4mm² conductors.

BS 1363-4 requires incoming screw terminals to be suitable for the same size/no. of conductors as socket-outlets.

Outgoing terminals (L, N and PE) must be suitable for connection of flexible (class 5) conductors in the range 0.5 mm² to 1.5 mm², or one conductor of solid (class 1) or stranded (class 2) with csa 1.5 mm² or 2.5 mm².

Examples of where manufacturer’s data or instructions are the only clue as to whether special preparation is required are:

Fixed socket-outlets to BS 1363-2 or connection units to BS 1363-4 with screwless terminals. The manufacturer may choose whether they are suitable for flexible (class 5) only, or solid + stranded (Class 1 + 2) only, or all 3 (class 1, 2 and 5).

Some crimps – especially the common red, blue & yellow – may not be suitable for solid (class 1) or stranded (class 2) conductors. Usually, if suitable for solid or stranded conductors, the crimp will have ridges around the inside

Some screwless connectors are only suitable for certain types of conductor – e.g. common screwless connectors without levers might only be suitable for solid or stranded (class 1 and 2) conductors.
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Crimping of flexible cord conductors

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