Surge Protection near you

NIST sets out the options by location and by who installs them, which is a more useful way to shop than by brand. There are several ways to install protection on your power supply: plug and play, do it yourself, hire a licensed electrician, or even call on your power company.

The question NIST's guide addresses head on is whether a protector installed at the service entrance is sufficient for the whole house. Its answer is careful and worth quoting in shape rather than in summary: since most homes today have some kind of two-link appliance, meaning something connected both to power and to a communications service such as telephone, cable or satellite, the prudent answer to the question would be no. That does not make the service-entrance device useless. NIST describes its important function as diverting large surges coming on the power line before they enter the house, and says a service-entrance protector makes the protection by plug-in protectors easier.

The second reason one device cannot cover a house is how branch circuits work. NIST notes that where a surge protector is installed on a particular branch circuit, the other receptacles on that same circuit might benefit from it, but that benefit is much less on other branch circuits. Practically, that means a strip behind the television protects the television and whatever else is on that circuit, and does very little for the furnace control board on the other side of the basement.

So the arrangement that actually works is layered: something at the service equipment to handle the large events coming in from outside, and protection at the appliances that are expensive, hard to replace or connected to more than one service. NIST is explicit that for multi-link appliances the combined kind matters, because a device connected to power and to cable or telephone at the same time can be damaged by the voltage difference between the two systems even when each is individually protected.

NIST puts this as plainly as it can be put: a very important point to keep in mind is that your surge protector will work by diverting the surges to ground, and the best surge protector in the world can be useless if grounding is not done properly. Everything else on the specification sheet is secondary to that.

The failure mode NIST spends the most space on is not a bad protector but uncoordinated utilities. It describes the problem of shifting reference potentials between the power service and the communications service, notes that the situation is made worse where the point of entry for power and the point of entry for communications are at opposite ends of the house with a large loop separating the two cables, and states that the situation is worse yet when an incoming service, cable television in particular, is not bonded to the power service ground, which it describes as a clear violation of the code that experience has shown is not so rare and that can result in severe damage to the appliance. It attributes one of the most frequent insurance damage claims, for video equipment, to exactly this uncoordinated grounding.

The remedies it describes are structural rather than product purchases. Where there is an opportunity to relocate the point of entry of the cable service or the telephone network interface device, bringing the service connections together next to each other reduces the problem by inter-system bonding of all the utilities serving the residence. Where that is impractical, it suggests an integrated multi-utility protector at the breaker panel that covers power, telephone and cable with the minimum length of bonding between them. Either way, this is a conversation with an electrician about where things enter the building, not a shopping decision.

Two numbers appear on almost every package, and NIST's guide explains both in a way that takes the marketing out of them. Joules is a simplified measure of the surge energy the protector can dissipate without damage to itself, and the higher the value the more energy it can handle, with typical values ranging from about 100 joules up to 1000 joules or more. NIST adds a caution: because the figure is often based on the three combinations of the wiring, many specifications show total joules rather than a breakdown, and maximum surge current may give better information.

Clamping voltage is the measure of the voltage-limiting capability of the protector, and NIST warns against the oversimplified perception that lower is automatically better. Many specifications show 330 volts, a number it says is embedded in the safety standard's values but is not a requirement, and it notes that somewhat higher clamping voltages, such as 400 volts or more, may be sufficient for protecting electronic appliances while making the protector itself less susceptible to damage from swells, meaning short increases in line voltage.

Two details are easy to miss and matter more than either number. A combined protector for power plus telephone or coax has an in side and an out side, and NIST advises reading the instructions or markings carefully to find which is which. And it warns that some combined protectors might not work very well if plugged into a two-blade receptacle using an adapter, which is a real issue in older American housing stock where ungrounded receptacles are still in service; on some devices an indicating light will signal the problem.

Homeowners tend to assume a protector dies heroically absorbing a lightning surge. NIST's account is less romantic: the prevailing opinion among specialists on surge protection is that most of the observed, and quite rare, catastrophic failures of surge protectors are caused by excessively high line voltage that can occur when there is a fault on the power system, and that failure from very large surges exceeding the protector's surge-handling capability is less likely than failure from high line voltage. In other words the thing that takes them out is usually a sustained overvoltage, not a spike.

The useful question, NIST says, is how long a useful life a surge protector can have, and it notes that today's well-designed protectors might reach their end of life prematurely if exposed to some exceptionally high and rare stress, but that for those tested to the relevant safety standard the way they fail should not be a hazard. That is the argument for buying listed equipment and for replacing indicator-equipped devices when the indicator says so, rather than for replacing everything after every thunderstorm.

One practical trap is worth naming. NIST observes that power companies sometimes suggest disconnecting appliances when a severe storm is approaching, which is no help if nobody is home, and adds a warning that is genuinely counterintuitive: pulling the power cord of an appliance that remains connected to a telephone line or cable might not be the best idea, because you lose the grounding that the power cord normally provides, which can be a safety problem should a surge arrive on the telephone or cable. If you unplug, unplug everything that connects to the device.

NIST is careful to separate two things that get conflated. Protection of the house against the direct effects of lightning is done by properly grounded lightning rods, a job it says is for professionals, and it adds the key qualification: lightning rods are intended to protect the structure of the house and avoid fires, and they do not prevent surges from happening in the wiring. Surge protection is about what arrives along the wires, whether power, telephone, cable or antenna, and NIST points out that each of those connections offers a path for a surge to come in, which is something often overlooked when the cause of damage is explained simply as a power surge.

Indirect effects reach a lot further than the strike. NIST describes them as less dramatic than a direct strike but reaching further out, either radiating around the strike or propagating along power lines, the telephone system and cable television, and gives everyday examples such as a garage door opening by itself or a surge arriving from the power company during a storm.

For people, the National Weather Service's indoor guidance is short and specific: stay off corded phones, computers and other electrical equipment that put you in direct contact with electricity, avoid plumbing including sinks, baths and faucets, stay away from windows and doors and off porches, and do not lie on concrete floors or lean against concrete walls. Surge protection is an equipment measure, not a personal safety measure, and the two should not be confused.

Most of the cost in this work is the electrician's time at the service equipment and the state of what is already there. What moves a quote is whether the panel has space for a snap-in device or the protector must be wired alongside the enclosure, whether the grounding electrode system and the bonding of metal piping are already sound or have to be established first, whether the power and communications services enter at the same place or at opposite ends of the house, whether a separate device is needed where a line leaves for an outbuilding or a well, whether the work is permitted and inspected, and how many point-of-use devices are being provided for multi-link equipment. NIST also suggests asking the electrician to look into the ratings of the device and the power system available fault current, to ensure compatibility, which is a good question to put in the request for quote.

LokalMatch is where you find the people to ask. You describe the panel, the house and what you are trying to protect, and licensed electricians in your area receive that request; the ones interested get in touch directly. Pros pay for the requests they receive and homeowners use the service free. LokalMatch does not install equipment, does not set prices and does not vet, rank or recommend any company, so verifying the licence and confirming the grounding work is included in the scope remain yours to do.