ADSS or Fig 8? Choosing Aerial Fibre for Real Spans

The moment fibre leaves the duct and takes to the poles, you have exactly two serious choices — and the wrong one gets picked more often than you’d think, usually on price.

ADSS first, because the name explains itself once: All-Dielectric Self-Supporting. No metal anywhere in the cable. Aramid yarns carry the span, so there’s no messenger wire, and nothing in it to pick up an induced current. That last point is the reason it exists. String fibre along a power corridor — which is where utility fibre goes — and a metallic cable becomes a liability: a fault path, an induction problem, an earthing chore for the next thirty years. ADSS is none of those things. With an anti-tracking sheath it even survives the electric field near high-tension conductors, which quietly eats ordinary jackets. Our AerioFib ADSS runs 1F to 432F, in builds for short, medium and long spans.

Fig 8 is the other animal. Look at it end-on and you see the name: a steel messenger and the fibre core moulded into one figure-of-eight profile. The steel does the mechanical work. That buys you longer spans, rough-weather margin, and a fast build — one attachment per pole, no lashing. The price is the metal itself: it must be earthed, and it has no business inside a power corridor. On telecom-only routes and long rural runs it’s the sturdy, economical choice. 1F to 288F, unitube or loose tube.

So the decision usually takes three questions. Does the route share structures with power? Then it’s ADSS and the conversation is over. How long are the spans and how ugly is the weather? Steel likes long spans and ice. And who maintains this for the next few decades? Fig 8’s earthing is a standing commitment; ADSS deletes it.

Both come single-mode or multi-mode, both are rated −40°C to +70°C, both built to IEC 60793/60794, EIA/TIA, ITU-T and Telcordia GR-20. The pair share a page: ADSS and Fig 8 aerial cables. For the wider map — duct, armoured, FTTH, fire-rated — see the fibre selection guide.