What it protects, and what it doesn't
A plug-in surge strip only protects what's plugged into it. The Department of Energy's safety reference says a suppressor doesn't protect anything back along the circuit, that not every power strip is a surge suppressor, and that suppressors differ in what they can handle. A whole-house unit covers the incoming power for the whole service instead.
It doesn't cover everything, though. The National Park Service's lightning protection brief says protection at the main service box should be paired with point-of-use protectors for sensitive electronics like computers, and that cable, phone and similar lines coming into the house need to be properly grounded. So keep good plug-in protectors on your TV and computer, and ask whether your cable or internet line is bonded to the house ground where it enters.
It also isn't a lightning rod system, which is a separate job. And it won't make it safe to use plugged-in devices during a storm: the CDC still says not to use anything connected to an outlet, like computers, washers or stoves, during a thunderstorm.
When it's worth raising
- You're getting a new panel or a service upgrade. In Philadelphia, L&I's EZ permit standard for residential service equipment lists “All services shall be provided with a surge protective device” (IRC E3606.5 / NEC 230.67). The city's applicable codes page shows the electrical code is based on the 2020 National Electrical Code. If you're in Bucks or Montgomery County, ask the electrician which code edition your township enforces.
- You have expensive equipment wired in: a furnace or heat pump with a control board, a smart thermostat, an induction range, an EV charger or solar. The Park Service brief notes surges can come from electrical malfunctions as well as lightning.
- Your house has more than one electrical service. The same brief says that with two or more service boxes, each needs its own protector. A separate service isn't the same thing as a subpanel, so have the electrician tell you which you have.
If your lights flicker, breakers trip or electronics keep resetting, don't treat a surge protector as the fix. Get that diagnosed first; our guide on lights dimming when the AC or furnace starts explains what an electrician will look at, and an older panel may need an evaluation for replacement anyway.
What to ask the electrician
- Which device, and is it listed? Ask for the brand and model and its UL 1449 listing, the standard the Park Service's sample electrical specifications name for surge suppressors. Don't settle for “commercial grade” or a big joule number as the whole description.
- Type 1 or Type 2, and where will it go? The 2020 code rule L&I cites, NEC 230.67, calls for one of those two types, built into the service equipment or right next to it, and applies whenever service equipment is replaced.
- Does it need its own breaker, and does my panel have room for one?
- How will I know it has stopped working? The Park Service brief describes units with indicator lights and says they may need replacement after severe or repeated surges. DOE's guidance calls a suppressor a one-time protector after a large surge. Ask what a normal and a failed light look like, and where to look without opening the panel.
- Who pulls the permit? Installing it is electrical work for a licensed electrician, not a homeowner job. Our Philadelphia electrical permit guide covers when L&I needs a permit and who can apply.
Get it in writing
Ask for an itemized quote that names the device, labor, any panel changes, and the permit and inspection. Ask for the manufacturer's instructions and the warranty terms, including any coverage for connected equipment and what it requires from you. Compare quotes on what's installed and how, not just on the device price.