Surge protectors

Not All surge protectors are created equal

Most people know that to ensure the safety of home and business electronics, you really need surge protection. What you may not know, though, is that this means more than an extra-strength outlet strip you keep stashed under your desk.

Whether you’re a business owner, working from home, or just an avid gamer, you’ve probably got some serious money wrapped up in your various technologies. You need to be sure you have adequate protection against power surges in order to protect that investment. 

What causes surges?

Spikes in electrical current — the “surge” in surge protection — occur in three main ways:

  • An interruption in electricity flow, followed by a short
  • An interruption during an increase in power delivery, which can cause electricity feedback in the system
  • A sudden increase in power system voltage brought on by internal or external causes (such as a lightning bolt)

Power surges are very common in electrical systems but not all of them are problematic. Surges that end up causing damage can vary in intensity, ranging from one volt over the 169-volt maximum most electronics can handle, to massive voltage overloads from events like lightning strikes. Depending on how powerful the surge is, it can blow fuses, fry the circuit boards in vulnerable electronic appliances, or even damage your electrical system.

When you hear “surge protection,” you might think “lightning.” There is good reason for that. The most damaging power surges are those caused by lightning, which transmits millions of volts of electricity into the ground. However, the most common power surges stem from human causes. These include downed power lines, faulty wiring, utility grid fluctuations, or the use of too many electrical devices at once. With these sorts of surges, damage to electronics can stack up over time, potentially shortening devices’ lifespans. This damage can be avoided through regulation of the current that flows into a device.

Surge protection devices

Whether they’re called surge protectors, spike suppressorssurge suppressorssurge diverters, or transient voltage surge suppressors (TVSS), the units that handle this power regulation chore are collectively referred to as surge protection devices (SPDs). They can be the plug-in models most people are familiar with, or they can be hard-wired into a business’ electrical grid, installed in power distribution panels, process control systems, communications systems, and other heavy-duty power-handling structures. Whatever form they take, SPDs fall into four basic categories.

  • A Type 1 SPD is called a surge arrester. It is designed to handle 1000 volts or less. These devices are typically installed by the local utility company.
  • A Type 2 SPD is called a transient voltage surge suppressor (TVSS). A TVSS can handle 600 volts or less.
  • A Type 3 SPD is the type of SPD found in most homes. It is a cord-connected, direct plug-in that is used to protect particular equipment (computers, printers, flat-screen monitors), and is the type commonly found in homes.
  • A Type 4 SPD is installed directly on the electrical component.

You should consider your investment in protection for your electronics carefully. Types 1 and 2 are generally installed in businesses that would face significant revenue or reputational loss if they went offline. But, having a home-based business and/or a collection of expensive and sensitive electronics might warrant upgrading from Type 2, the type usually found in homes, to Type 3 SPDs. Some units traveling under the “surge protector” name are little more than minimally buffered power strips.

What to look for offers a checklist of what to look for when choosing an SPD:

  • UL Listed (“UL 1449 Listed” is good. “UL 1449 Revision 2” is better). “UL tested,” “meets UL,” and “UL” do NOT necessarily indicate quality surge protection.
  • For a plug strip, the clamping voltage should be UL 330 volts, the surge-current rating should be at least 36,000 amps, and the joule rating should be at least 360 joules.
  • For permanently installed surge protection, the clamping voltage should be no more than UL 400 volts, the surge-current rating should be at least 36,000 amps, and the joule rating should be at least 360 joules.
  • The SPD should have a failure indicator light or buzzer and a status light (for indicating proper wiring and grounding).
  • Find one with a recessed on/off switch on strip surge protectors.
  • Look for an SPD that has multi-mode protection (line to neutral, line to ground, neutral to ground).
  • If the SPDs has multiple plug-ins, make sure there is adequate plug spacing for your needs.


The information included here was obtained from sources believed to be reliable, however Grinnell Mutual Reinsurance Company and its employees make no guarantee of results and assume no liability in connection with any training, materials, suggestions, or information provided. It is the user’s responsibility to confirm compliance with any applicable local, state, or federal regulations. Information obtained from or via Grinnell Mutual Reinsurance Company should not be used as the basis for legal advice and should be confirmed with alternative sources.  

Sources: Alpine Intel: Cropp Metcalfe Services Tara Energy