Current as of October 8, 2026.

Every hurricane season brings the same question from homeowners who already have a whole-house surge protector at the main panel: does that one device cover everything? When a big storm works the grid over — nearby lightning, lines dropping and re-energizing, utility switching stacked on top of it all — surges ride your wiring at levels your electronics were never built for. The panel unit is the right start. It isn't the whole job.

Short answer: the panel unit is the foundation, not the finished job. It clamps surges at the service entrance — but some voltage still gets through your branch wiring at levels that can damage the most expensive electronics in the house, and surges also enter through paths the panel unit never sees: your cable line, phone line, and internet wiring. Protecting the rest means adding protection at the equipment itself — the condenser disconnect, the air handler, the pool panel, the garage subpanel, and every low-voltage entry point. (SPD stands for surge protective device — our October 6 guide covers the panel-unit basics.)

What you see on the walk around

Circle the house from the meter: the gray disconnect beside the condenser (the fused switch box that cuts power to the outdoor unit); the air handler or mini-split wall units; the pool equipment pad; the garage or workshop subpanel; where cable, phone, and internet lines come in. Each is a place a surge either gets stopped or gets through — and the panel device is only the first line of defense.

What's actually happening inside the wires

A panel SPD works like a pressure relief valve: its metal oxide varistors (MOVs) conduct in nanoseconds above a clamping threshold, diverting surge current through neutral and ground. MOVs are sacrificial — each absorbed surge degrades them slightly, so the unit's indicator light is only a coarse end-of-life signal, not a health meter. VPR — the let-through voltage under UL 1449 (lower is better) — and kA, the manufacturer's rated maximum surge current, describe how well.

Two gaps: the let-through isn't zero — several hundred volts can still pass, with branch wiring impedance (long wire runs resist fast-moving surges) adding more — and it never touches surges arriving on the cable drop, phone line, or ethernet.

And not every surge comes from the sky. Your own appliances make them: every time a motor cycles — the condenser kicking on, the refrigerator compressor, the pool pump — it sends a brief voltage spike back onto your home's wiring. Individually small, but they happen daily, and they start downstream of the panel, already past your first line of defense. Another reason the sensitive stuff earns its own point-of-use protection.

High-efficiency HVAC carries inverter boards, ECM motors, and control boards — low-voltage electronics built to switch power precisely, not to absorb it. MARS's own literature puts it plainly: \"Today's HVAC equipment is more susceptible to power issues than equipment produced 10 years ago... sophisticated electronics coupled with the increased frequency and severity of storms.\" An equipment-level SPD mounted at the disconnect clamps the surge closer to those boards — the same pressure-relief idea, positioned where the damage happens.

What a professional checks

A good pro starts with the ground, not the panel: surge current diverts through neutral and ground, so corroded, loose, or undersized grounding — not unusual in the area's older housing stock — compromises the whole scheme. Then the walk:

The condenser disconnect and air handler. The big one — because a dead inverter board means no cooling and an expensive part. They mount right at the disconnect — equipment-level units from RectorSeal, DITEK, and MARS install in or at the disconnect enclosure, wired per each manufacturer's instructions (licensed-electrician work, not a homeowner add-on). High-efficiency and mini-split equipment has the most to lose.

The pool equipment panel. Automation controllers, heaters, pumps, sanitizers — thousands of dollars of electronics sitting outdoors, fully exposed, running equipment your pool can't go without. A surge that takes out the automation controller doesn't just kill a board — it kills filtration and sanitation until the part comes in. Intermatic's PS3000 is built for this spot: pool panel, sub-panel, junction box, or spa disconnect.

Subpanels. The garage or workshop subpanel feeds its own branch circuits — and every foot of feeder between it and the main panel is distance the main-panel unit can't fully cover. A second SPD there shortens it.

Low-voltage entries. Your cable and phone lines usually arrive aerially — strung pole to pole, fully exposed — and they terminate directly at expensive electronics: the modem, the router, the TVs and computers downstream of them. The panel SPD never sees these paths at all. So: where do the coax, phone line, and internet wiring enter — and is there a listed protector there, bonded to the service ground? Purpose-built units exist: Tii's 210/212 coax protector in-line at the ground block, Tii's 355M telephone module inside the Network Interface Device, and DITEK's ethernet units in-line ahead of the equipment. Wired into the signal line itself — not a plug-in power strip at the desk. (Fiber-optic service is the exception — glass fiber doesn't conduct surge current into the house the way copper does.)

The code — and the safety boundary

This is licensed-electrician work, full stop — panels, disconnects, and service equipment are not homeowner territory, and New Orleans requires an electrical permit for it through the Dept. of Safety & Permits.

Code, manufacturer recommendation, and best practice are three different things in Louisiana right now:

\nNEC 230.67 (2020): the 2020 NEC requires a Type 1 or Type 2 SPD on all services supplying dwelling units — integral to the service equipment or immediately adjacent, with an exception allowing the SPD at each next-level distribution panel downstream instead, and the requirement applies when service equipment is replaced. Louisiana enforces this section with one state amendment: services for manufactured housing units are excepted (La. Admin. Code tit. 17, § I-115). In plain terms: the Code compels a panel SPD on new construction and service-equipment replacements — not as a blanket retrofit mandate for every existing home. For an existing home with an untouched service, it's strong recommendation. (Louisiana has approved the 2023 NEC, effective January 1, 2027; until then the 2020 edition as amended is the statewide baseline.) The 2023 NEC's feeder/subpanel SPD rule (Art. 215.18) is not Louisiana law yet — subpanel SPDs here are a strong recommendation, not code.
\nArticle 440 (HVAC): no surge requirement in the 2020 or 2023 editions — HVAC-unit SPDs are manufacturer recommendation and good practice only. A Mersen distributor page markets its HVAC/R SPD as \"compliant with 2020 NEC article 230.67\" — but 230.67 governs dwelling-unit services, not HVAC equipment.
\nArticle 680 (pools): no surge requirement — pool code is GFCI protection plus equipotential bonding; pool SPDs are a sensible upgrade, not code.
\nCommunications (NEC 2020 Arts. 805.90, 820.90, 830.90): these do require a listed primary protector (the code-required overvoltage guard for the incoming line) at the building entrance — communications circuits, CATV/coax, network-powered broadband — in, on, or immediately adjacent to the building, as close as practicable to the point of entrance, bonded to the service ground. Entrance-only.
\nNew Orleans: nola.gov states electrical work is governed by the NEC. Our research found no city amendments on surge protection — a research finding, not a certainty.

The honest timeline: a licensed install takes scheduling — put surge protection on the list before the next storm, not after. Every storm season's damage reports show which stops needed it most.

What to ask before you hire

\"Can you check my grounding first — and what happens to surge protection if it's not adequate?\"
\"For my HVAC: do you recommend SPDs at the condenser disconnect and the air handler — and which unit?\"
\"My pool panel runs my automation and pumps — does an SPD make sense there, and where would it mount?\"
\"Where do my cable, phone, and internet lines enter — and are the entrance protectors listed and bonded to the service ground?\"
\"Are you pulling the electrical permit through the Dept. of Safety & Permits?\" (The answer should be yes.)

Sources: NEC 2020 Articles 230.67, 440, 680, 805.90, 820.90, and 830.90; La. Admin. Code tit. 17, § I-115 (Louisiana amendment: manufactured-housing services excepted from 230.67(A)); LSUCCC Title 17 approved language (2023 NEC adoption effective January 1, 2027); NEC 2023 Article 215.18 (not yet Louisiana law); Louisiana statewide enforcement of the 2020 NEC, effective January 1, 2023; product literature — RectorSeal RSH-50, DITEK DTK-120/240CM+, MARS 83905, Intermatic PS3000, Tii 210/212 (UL 497C), Tii 355M (UL 497), DITEK DTK-MRJ45C5e and DTK-MRJPOES (UL497B); City of New Orleans Dept. of Safety & Permits electrical permit requirements (nola.gov); Mersen distributor page (HVAC/R SPD marketed as 230.67-compliant; cited in the Code section). Each brand's ratings are that brand's published numbers.

Want surge protection mapped across your whole property — panel, HVAC, pool, and low-voltage lines? Call (504) 552-3785 for a free project review, or visit abestpros.com.

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Understanding Where Surge Protection Matters Most

Learn how to protect your property from unexpected power surges effectively.

Identifying Critical Areas for Surge Protection

Secure Your Property Today

Contact ABest Pros for expert surge protection solutions tailored to your needs.