Every storm season destroys equipment a surge protector would have saved. Here's how to protect a site properly, from a team that specs this every week.

Every year, Australian storms destroy radios, repeaters, routers and cameras that a $100 surge protector would have saved. If you operate anything with an antenna — a UHF base station, a Cel-Fi repeater, a Starlink dish, a WISP link, PoE cameras on a pole — this guide explains exactly how surge damage happens, the three layers of protection that stop it, and how to choose the right parts. It's the advice we give customers over the phone every week, written down.

How surges actually destroy your equipment

A direct lightning strike is rare. What kills gear, over and over, is induced surge: a strike hundreds of metres away induces thousands of volts onto any long conductor — your coax feeder, your Ethernet run to the shed, the mains wiring. That energy travels down the cable and arrives at the most delicate thing in the building: the receiver front-end of your radio, the WAN port of your router, the PoE port of your switch.

The cruel part is that damage is often partial. A radio that "survived" a storm season may have lost 10 dB of receive sensitivity — it still works, just badly, and you blame the antenna or the carrier. Surge protection isn't only about preventing dead equipment; it's about keeping performance you paid for.

The three layers of protection

Layer 1 — Earthing and bonding (the foundation)

Every surge protector is only as good as its path to earth. Before buying any device, the site needs: a proper earth point (electrode or building earth per AS 1768, the Australian lightning protection standard), the antenna mast/mount bonded to it, and the coax shield grounded at the entry point to the building. On towers, the feeder shield is also grounded at the top and bottom of the vertical run. Our grounding kits and earthing hardware cover the coax side; mains-side earthing is licensed-electrician territory — use one.

Layer 2 — Protect every conductor that enters the building

This is the rule people miss: lightning doesn't care which cable it uses. Protect the coax and it will come in through the Ethernet. The checklist for any site:

• Every coax feeder gets an RF surge protector at the entry panel — see our RF surge protectors.
• Every outdoor Ethernet/PoE run (cameras, outdoor APs, wireless bridges) gets a data-line surge protector rated for its speed and PoE class.
• The mains supply feeding the equipment gets surge diversion at the switchboard or a quality surge-protected outlet (electrician's job at the board).

Layer 3 — The RF surge protector itself

A coaxial surge protector sits in-line on the feeder, passing your signal with almost no loss (typically 0.1 dB) while diverting surge energy to ground before it reaches the radio. Two main technologies:

• Gas discharge tube (GDT): a sealed spark gap that fires at a set voltage. Wideband and replaceable-element in many models; the workhorse for general sites.
• DC-blocked (blocking capacitor + GDT): adds a series capacitor that blocks DC entirely and delivers much lower let-through energy — the tighter protection for expensive receivers. The trade-off: it cannot pass DC power up the cable.

How to choose: the six specs that matter

• Frequency range — the protector must cover your operating frequency. A 125 MHz–1 GHz unit like the PolyPhaser IS-50NX-C2 suits VHF/UHF land-mobile and telemetry; HF stations need coverage down to 10 MHz or below, like the 1.5 kW-rated PolyPhaser IS-B50LN-C2; cellular and 5G paths need units rated to 6 GHz.
• Power rating — must exceed your transmit power at your frequency (ratings step down as frequency rises — check the band table, not just the headline number).
• DC pass or DC block — if the feeder powers something (masthead amp, tower-top LNA, bias-tee, some GPS antennas), you need a DC-pass model. A DC-blocked unit will silently cut power to the device. This is the most common ordering mistake we see.
• Let-through energy — the energy that still reaches your equipment during a strike. Lower is better: quality units let through millionths of a joule (e.g. 120–220 µJ at 3 kA) — the difference between a logged event and a repair bill.
• Multi-strike rating — storms deliver strike after strike. Look for multi-strike-rated units (20–50 kA on the 8/20 µs waveform) that survive repeated events rather than sacrificing themselves on the first.
• Connector and mounting — match your feeder connectors (N-type for most sites, 4.3-10 or 7-16 DIN on carrier-grade paths), and choose bulkhead-mount units where the protector passes through the grounded entry plate itself — the cleanest possible earth path.

"Do I need an RCD or a surge protector?" — both, they do different jobs

This confusion comes up constantly. An RCD (safety switch) protects people: it cuts power when current leaks to earth, as in an electric shock. It does nothing against surges. A surge protector (SPD) protects equipment: it diverts transient over-voltages to earth. A properly protected site has RCDs for safety, surge diversion at the switchboard for the mains, and RF/data-line protectors for every cable entering from outside. One never substitutes for the other.

Installation rules that make the difference

• Mount at the entry point, on a grounded bulkhead panel — not on a shelf next to the radio. Ten metres of cable after the protector is ten metres of new antenna for re-induction.
• Keep the earth lead short, straight and fat. Every bend and every metre adds inductance that turns "diverted" energy back into voltage. Wide strap beats round wire.
• Bond everything to one earth point. Separate earths at different potentials are how surge current ends up flowing through your equipment between them.
• Torque connectors properly and weatherproof outdoor joints — a corroded connection upstream of the protector defeats it.
• After a known strike, inspect. Gas tubes are sacrificial over their life; many PolyPhaser models have replaceable elements. A protector that gave its life did its job — replace it before the next storm cell.

Quick answers

Does one protector cover my whole site? No — one per penetrating cable: every feeder, every outdoor Ethernet run, plus the mains. Surges take whichever door you left open.

Will it degrade my signal? A quality unit inserts about 0.1 dB of loss — unmeasurable in practice. Cheap unrated units are another story, which is why we only stock engineered product.

What about my Cel-Fi repeater or Starlink? Same rules: protect the donor-antenna coax at entry (frequency-appropriate, usually DC-blocked for repeater donors) and the Ethernet/PoE side with a data-line protector.

Is it required? AS 1768 is the Australian standard for lightning protection, and some insurers ask pointed questions after a claim. But the practical maths is simpler: protectors cost tens of dollars; the radios, routers and cameras behind them cost thousands.

Get the protection right the first time

Browse RF surge protectors and data surge protectors, or contact us.

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