The Guide to Surge Protectors

By: Jonathan Z. Kremer

SCENARIO 1

You’re trying to get some sleep. There is a jolting thunderstorm outside. The windows are rattling and there are bright flashes of light coming in from the sky. You finally turn over and go back to sleep. The next morning you get up and notice that the refrigerator is not working, your computer is not booting, and your microwave is dead.

SCENARIO 2

You’re sitting home trying to get some last minute work done, when the electricity starts to act up. The lights go dim and then bright. After another minute or two everything goes black. You wait awhile, but then decide to go over to the neighbor to see if they are having similar problems. As you start to leave, the power goes back on. You say “great, back to work.” But as you head back to the living room you realize that your stereo isn’t working. Then you notice that the computer monitor is flickering and your computer just makes funny noises when you try to put it on.

Both above scenarios are examples of the type of damage electrical surges can cause. A voltage surge is a temporary increase in “normal” electrical line voltage, which is usually not more than 500-600 volts. A surge or spike (same as a surge but for a very short period of time – although it can measure in the thousands of volts) can be caused by downed power lines, a blown transformer, lightning, electric power grid switching, etc. Surges don’t only travel through the electrical cables, but through TV antennas, telephone cables, or any other object that acts as a conductor. Appliances and electronics aren’t the only thing that surges can destroy. They can ruin electrical outlets, light switches, light bulbs, air conditioner components, garage door openers…and more.

Other types of power interference:

Although surges are probably the most serious form of power interference, they are not the only form.

A Voltage Dip (sag or brownout): A voltage dip happens when high-power electrical devices (such as elevators, air conditioners, dishwashers, and refrigerators) come on, and create sudden, brief demands for power which upsets the steady voltage flow in the electrical system.

Flickering or dimming lights are a common symptoms of a voltage dip.

EMI: There is also electromagnetic interference (EMI). This happens when the electromagnetic field of one device disrupts, impedes or degrades the electromagnetic field of another device by coming into proximity with it. This can scramble computer memory and disturb TV and radio reception. Fortunately, it doesn’t cause physical damage to appliances and electronic devices.

How can you protect yourself?

Your electrical equipment can be protected by using a surge protector or UPS (To learn more about UPSs see “Do You Need A UPS?”). A surge protector (also called a surge suppressor, surge arrestor, transient voltage surge suppressors (TVSS), secondary surge arresters, or surge strip) is a device which is specially designed to absorb any voltage spikes or surges. This prevents the voltage fluctuation from being passed on to delicate electronic circuitry. Some filter out the electromagnetic interference (EMI) and radio frequency interference (RFI) too.

There are basically two types of surge protectors.

Service entrance surge protectors – These are hard wired to the service panel (main electrical panel) where your circuit breakers are located, or next to your electric meter. These devices are designed to stop harmful surges before they can travel towards the electronic equipment in your home.

Point-of-use surge protector – These devices are used near the appliance that is being protected. It includes the type of surge protectors that plug into a wall outlet.

Surge protectors are rated for different purposes and uses, which fall under two categories:

Transient Voltage Surge Suppressor (TVSS): TVSSs are rated and designed to be used after the main disconnect (main breaker or switch) in the service panel. In the US, they are tested according to Underwriters Laboratory standard (UL 1449). UL 1449 assigns a clamping voltage to the TVSS which can be used for comparison from one product to the next. The clamping voltage is the maximum amount of voltage that a surge protector will allow through itself before it will suppress the power surge.

These devices include the point-of-use surge protectors and service entrance surge protectors mounted on the electrical panel (after the main disconnect).

Secondary Surge Arrester: These devices are tested and rated for use before the primary disconnect to a facility (the main electrical panel). Unlike TVSS type protectors, secondary surge arresters can be connected both before or after the main-disconnect. In the US they are rated by the recommendations of the Institute of Electrical and Electronics Engineers (IEEE) standard C62.11. A clamping voltage is not assigned by the IEEE (C62.11) for secondary surge arresters, making it difficult to compare the capabilities of the different type surge protectors.

Secondary surge arresters include both the meter-mount surge protectors and the plug-on surge protectors that snap into the electrical panel.

Important note #1:

On some surge protectors you will see the term “Let Through Voltage”. The “let through voltage” is the voltage that passes through the surge protector to your devices. Although the “let through voltage”, is similar to the clamping voltage, they are not the same.

The clamping voltage will be equal to the “let through voltage” only if the power surge is exactly the size, shape and duration of the 6,000-volt surge required in the UL 1449 test standard. If the surge is higher, the “let through voltage” will most likely be higher too.

When protecting your home it’s important to remember that a service entrance suppressor can’t stop surges sufficiently by itself. Up to 15% of excess voltage may leak by. That’s where “point-of-use” surge protectors come into play. They act as an additional buffer between individual appliances and wall outlets.

Surprisingly, there is a lot of controversy surrounding surge protector technology, causing flaming debates across the Web. Electronic experts are somewhat divided over the best way to deal with power surges, causing a situation where each manufacturer claims that their technology is inherently the best. One thing is for certain, no surge protector is 100% effective. Not only is it possible that a top of the line piece of equipment can have serious problems or defects, but those unlucky enough to experience a violent burst of voltage from a direct or very close hit of lightning, will probably find their surge protector fried and their appliances damaged never-the-less. A very close or direct hit of lightning is simply too much for your average surge protector (or UPS) to deal with. If your surge protector is in the way of the lightning’s path, all or part of the lightning will just flash over or through the device – regardless of the number of capacitors and battery banks incorporated. Of course this does not mean that you should not use a surge protector (or UPS). Using top quality surge protectors will give you a very high percentage of protection from everyday power line spikes and distant lightning strikes. But when lightning hits directly or nearby, all bets are off.

Tip:

When a lighting storm is near, the best way to protect your appliances from a lightning strike is to unplug them from the outlets, together with your surge protectors and UPSs. A lightning bolt, that can melt holes in steel and jump through kilometers of empty air, isn’t going to even notice the “surge protection” electronics in a power strip or UPS and it isn’t going to be stopped by the tiny air gap inside an on/off switch. Don’t forget to unplug telephone, cable, and antenna connections too.

Important Note #2:

A GOOD GROUNDING IS CRUCIAL for surge protectors and UPSs to work. Most Surge-Protection Devices or (SPDs for short) are composed of Metal Oxide Varistors (MOVs). These small MOVs are designed to “turn on” or activate at a given voltage level. When it detects voltages over a certain amount, it immediately diverts the surge to the ground. Therefore surge protectors must be plugged into three prong outlets and the grounding system must be in working order. If there are any grounding problems, a competent electrician should be brought in to make the necessary repairs and/or changes.

Many surge protectors have a ground indicator light which will show if your outlet is properly grounded or not.

What to look for when buying.

As with just about everything, there is a high end and a low end to surge protectors, and you typically get what you pay for. Low-end surge protection units offer very little protection, and the circuits in the protector are prone to quick failure. So how do you know what to look for?

The following are some specifications to look for when shopping for Point-of-Use Surge Protectors:
  • Choose only those surge protectors that have been tested: UL 1449 2nd Edition is a test standard (USA) that was developed by UL (Underwriters Laboratory) in conjunction with the industry, to certify product ratings and ensure proper markings on TVSS products. Through this test, the clamping voltage is determined. For other test standards see “Important note #4” below.
  • Clamping Voltage (Rating): Purchase surge protector with a listed clamping voltage of 330-volts, the best rating given under UL 1449. It will not be difficult to find TVSSs that plug into outlets and have a clamping voltage of 330-volts.
  • Let Through Voltage (Rating): This is the amount of voltage that passes through the surge protector to your devices (see above). Try to get a surge protector with the lowest possible “let through voltage” rating.
  • Joule rating: A joule is a measurement of energy. The joule rating on a surge protector shows the amount of energy that a device is capable of absorbing. Some say that the higher the joule rating, the better the unit is able to protect your equipment and the longer it will last. Most do not agree. IEEE, IEC, and NEMA do not recommend using joules ratings when comparing surge devices because they can provide misleading and conflicting information. One device may have a lower joule rating than another, but may have a much lower let-through voltage and therefore offer better protection.
  • 3-Line protection: Make sure the surge protection is on all 3 electrical lines. The device should indicate protection for Line to Neutral (L-N), Line to Ground (L-G), and Neutral to Ground (N-G).
  • Power shut down protection: This feature shuts off power to all outlets once the unit has reached its capacity to protect. Power shut down prevents additional surges and spikes from reaching connected equipment before the surge protector is replaced. This assures you that if the unit has power, it is protecting.
Important Note #3:

In most surge protectors there is a key component called a metal oxide varistor (or “MOV”), which diverts the extra voltage to the ground. Unfortunately MOVs will divert a finite number of power surges until they are eventually destroyed. It’s a good idea to check with your manufacturer to find out what type of warranty your unit has, and if it’s possible to have your unit examined every so often to insure that it is still protecting your equipment. Newer high quality suppressors come with lights and audible alarms that tell you when the MOVs have given up on the job. Both the “service entrance” and “point-of-use” surge suppressors are available with this convenient feature.

Circuit breaker: A breaker stops the flow of electricity when a circuit is overloaded and is not related to surges or spikes.

Diagnostic lights: Diagnostic lights are very helpful in monitoring the effectiveness of the surge protector. For instance, a ground indicator light displays whether or not the device is properly grounded — crucial knowledge, because you will not be protected if it isn’t.

Telephone and Coax Protection: Look for a surge protector with telephone and coax cable jacks for protection of those lines. Remember, power surges can enter through the electrical, telephone, or coax lines.

Response time: This rating indicates how fast a surge protector can react. The faster the better.

Good Warranty: Find an established manufacturer with a good reputation. Their warranty should cover any damage to the equipment that is connected through their surge protection device.

Service entrance surge protection devices will either be a TVSS or a secondary surge arrester. It is not possible to compare the capabilities of the two because they are tested differently.

The following are some specifications to look for when shopping for Service Entrance Surge Protection:

Make sure the device has been tested: It is very important that the device has been tested. For those manufactured or sold in the USA look for a secondary surge arrester that is tested according to the recommendations of IEEE C62.11 or a TVSS that has been tested in accordance with UL 1449, 2nd Edition.

Fuse Protection: Look for a TVSS device that has thermal fuse protection. If the device is a secondary surge arrester, make sure it is fused.

Clamping Voltage (Rating): It was mentioned in the section above that the best rating given under UL 1449 is 330 volts. Service entrance TVSS surge protectors will typically have a clamping voltage higher than 330 volts. The lower the clamping voltage the better the protection.

Those service entrance surge protection devices classified as secondary surge arresters will not have a clamping voltage because they are not tested to UL 1449 standards. Therefore you should get a device that is tested according to the recommendations of IEEE C62.11. Talk with the manufacturer about the device’s capabilities. Since there is no standardized test method for secondary surge arresters, each manufacturer may test their product differently, making a performance comparison between products difficult or impossible.

Joule rating: The joule rating on a surge protector shows the amount of energy that a device is capable of absorbing.

Telephone and Cable TV Protection: Install surge protection on the telephone and cable TV lines as well as the electrical line. This can be accomplished either with one surge protection device or seperate devices for each utility line.

3-Line protection: Make sure the surge protection is on all 3 electrical lines. The device should indicate protection for Line to Neutral (L-N), Line to Ground (L-G), and Neutral to Ground (N-G).

Working Indicator Light: Most all service entrance surge protection devices have indicator lights that will signify if there are any problems with the protection.

Good Warranty: Find an established manufacturer with a good reputation.

Important Note #4:

In Israel, secondary surge arresters are difficult to come by. Service entrance surge protectors of the TVSS type can be found. Many European companies have a UL 1449 rating. Others are usually not rated by the above testing institutions. Some point-of-use surge protectors are ISO 9000 approved. Standards from other countries include:

NFC 61740 (France)
VDE 0675 (Germany)
UL 1449 (USA)
IEC 61643-1-1 (International)

For Telecom equipment:

IEC 61644-1 (International)
ITU-T recommendations K11, K12, K17, K20, K22, K36 (International)
UL 497A/B (USA)

Jonathan Z. Kremer (better known as Yoni) is the proprietor of “Yoni – Electrical Design and Installations“, a Maale Adumim (Israel) based business that has been serving primarily Jerusalem, Maale Adumim, and surrounding areas since 1989. We undertake various forms of electrical work including renovations, maintenance, installations, and repairs – encompassing the domestic (home), industrial and commercial arenas. We believe that our success tomorrow will be determined by how well we serve you today. https://yoni.kremer.co.il