Cable ties: sizes, materials and how strong each one is

What a cable tie is

A cable tie is a toothed strap with a locking head at one end. The tail is pulled through the head, and a pawl inside it catches the teeth so the loop can tighten but not slip back. Standard ties are single-use and have to be cut off; releasable versions have a tab that lifts the pawl.

The plastic kind is moulded from polyamide, the material sold as nylon. ABB’s Ty-Rap catalogue gives the spread of one range: lengths from 112 to 1,214 mm, widths from 2.4 to 13.2 mm, and bundles up to 381 mm across. Its ties are made to EN/IEC 62275, the product standard for cable ties in electrical installations.

Cable tie sizes and loop strength

The figure that matters is loop tensile strength: the pull a closed tie takes before it fails. In the ABB range it follows the width, and the catalogue codes each width with its minimum strength:

Cable tie sizes and loop strength

Width	Minimum loop strength	About (our calculation, N ÷ 9.81)
2.4 mm	80 N	8 kg
3.3 mm	130 N	13 kg
3.6 mm	180 N	18 kg
4.6 mm	220 N	22 kg
7.6 mm	540 N	55 kg
8.8 mm	780 N	80 kg
13.2 mm	1,120 N	114 kg

Length only sets how big a bundle the tie can close around. A long 2.4 mm tie is still an 80 N tie, so heavy cable on a tray — the kind of route Prysmian’s data sheet lists for armoured cable — calls for the wider sizes.

Nylon 6.6, nylon 12 or stainless steel

TE Connectivity’s cable tie range shows how the material changes what a tie can survive:

Nylon 6.6, nylon 12 or stainless steel

Material	Colour	Service temperature	Fitting temperature	Notes from TE
Polyamide 6.6	natural or black	−40°C to +80°C	−10°C to +60°C	resists oils and greases; UL 94 V-2 flammability
Polyamide 12	black	−40°C to +80°C	−20°C to +60°C	resists ultraviolet light and salty air; UL 94 HB
Stainless steel AISI 316	metal, some powder-coated	not stated on the page	—	for marine work, power stations and underground cable laying

The coating on some steel ties does a second job: it keeps the tie from touching a different metal and setting up corrosion between the two. TE also lists hoses, alongside wires and harnesses, among what its ties bundle and mount.

Black cable ties for outdoor use

Colour is a specification, not a style choice. ABB makes its ties in natural colour for indoor work and in UV-resistant black for outdoor work; TE likewise offers black UV-resistant ties for use outside.

Storage matters too. The ABB catalogue notes that nylon is sensitive to its surroundings: the ties leave the factory conditioned with moisture, so they should be kept in a cool, dry place out of direct sun, with the bag left sealed until they are needed.

Cable ties and fire: the UK rule

Plastic ties lose their grip in a fire. The UK industry body BEAMA, in its guide on premature collapse, traces the rule back to a tower block fire in Southampton, where two firefighters died after becoming caught in cables that fell once the plastic trunking holding them melted.

BS 7671, regulation 521.10.202, now requires wiring to be supported so that it will not collapse early in a fire. BEAMA’s guide says thermoplastic PVC-U softens at 80–100°C, calls plastic cable ties very high-risk items whose use should be limited, and points to metal fixings instead. The regulation is British; it is cited here for the reasoning behind it, not as a rule that applies in Tanzania.