Surge suppression has come a long way over the years. Some of us remember when purchasing our first computer we also had to purchase an APC power back-up that had surge protection, power filtering and power back-up as a much-needed secondary function. Today we plug our computers into surge strips from Walmart or Best Buy. Some are quality units costing upwards of a hundred dollars, some are not.

PQ Power Quality & SPD Surge Protection Device

Surge Protection is often referred to as Power Quality when discussing their function, application and properties. To achieve power quality we may implement a SPD or surge protection device or other means to achieve a desired level of quality. Trade publications now devote an entire column every month to this and other related topics.

Today’s Surge Protector AKA Surge Suppressor / Surge strips / Power Strips

These are possibly the most misrepresented of any electrical device on the market today and one of the leading causes of fires in our homes.

Years ago Tripp Lite was the only trusted brand when industrial applications were concerned. We used Daykin or Sola transformers to provide clean power for sensitive electronics, PLC's and CPU's. Tripp Lite’s Isobar was the go-to for point-of-use filters or protection. They were made in the USA and costly. The housings were steel or aluminum with cooling fans or heat sinks. Today you see them in plastic and imported. I see identical units at the bargain store with a different name or logo printed on them and know they are not the same.

Of course you can find the original Isobar units, and they are still the go-to brand.

We will get back to this type of unit later in the article.

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These images are used with permission from Tripp Lite. ©2019, All Rights Reserved.

Why Should I Do More?

For me it started 12 years ago. My new home was damaged by a surge or line fault that occurred when a contractor digging a basement hit the feeder supplying our new development. The surge not only traveled the service cable but induced a voltage and current through the soil to the buried telephone and cable lines damaging that equipment as well. This single incident resulted in thousands of dollars in damage.

The utility company, instead of replacing the compromised feeder, tapped into an already problematic circuit to supply our new development. Soon after, furnaces, Smart appliances, and anything with a circuit board started failing.

First was to identify the problem.

Along with a few homeowners I filed a claim and complaint. To go through this process you really need to be motivated and have a lot of time on your hands. Due to the recent events the utility installed a meter/event recorder on my home. The tech said he would return in a few days to retrieve the data.

One month later the tech returned and reviewed the data, and I asked, “Ok, what were the results?”

…..…. silence…..…. then “Your site manager will contact you.”

If You Want Something Done

I soon realized the Energy Co could really care less about one of the thousand developments occurring during that housing boom. Their response was “It’s on the books!" So I had to find a solution.

Note: It’s still on the books.

That’s the Ticket!

Soon after, I attended an Electrical Contractors convention. When I visited the Leviton booth, I was surprised to see a device identical to the recorder that was on my home. When I inquired I learned that it was a Whole House Surge Suppressor. The rep was excited that another recognized the importance of Power Quality and the device sitting on the table. When he stated that “This is the same unit that utility companies rent to their customers,” I knew I had found the solution.

Since that day, I now have a website and a matching toll free number primarily devoted to Surge Protection and have sold and installed well over a hundred units.

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This image is courtesy of @siggy, ©2019, All Rights Reserved.

Check with your local authority when installing TYPE-1 or 2 SPD’S.

This is my photo of a TYPE-1 SPD. It’s now in use as click bait by a distributor trying to sell you an inexpensive TYPE-2 SPD.

Properly Sized & Installed Equipment

Today, most homeowners see Mr. Holmes's face on a $69.99 whole-house device and think that’s all that’s needed. They are taught to look at the joules rating to gauge the effectiveness of a product. Joules is a good indicator but not the most important. Clamping threshold or gate voltage and the duration it can sustain that clamping of over-voltage is even more important. For instance: you could have a million joules with a 200-volt gate or clamp. That thing would last a lifetime but 200 volts is not a suitable voltage for a 120-volt device. A hundred and fifty (150) volts is a good place to start, and to give credit, the Isobar unit I looked at had a 140-volt gate.

Also remember, one good hit from a lightning strike or a car hitting a utility pole can relinquish some of the best equipment to the curb.

Joules=Life of unit or how much it can absorb in its lifetime

Rule of Thumb for a safe operating voltage is +/- 10%
Due to PQ demands and confusion surrounding SPD’S and further fueled by imports and increases in fire-related incidents, UL laboratory, located on Cape Canaveral, began extensive testing and created a Standard known as UL 1449 3rd Edition. This revision created a Installation System of Type 1 thru 5.

Note: Florida and the Cape are well known as the Lightning Capital of the World and for UL Labs & SPD testing respectively.

UL statement

UL 1449 is Underwriters Laboratories’ safety and performance standard for surge protection equipment. In 2009, this Standard was revised to the 3rd Edition. In addition to some nomenclature changes, there were two very important objectives for revising the UL 1449 Standard: to harmonize with the international standards for surge protective equipment (IEC 61643-1) and to modify performance tests to better simulate real world exposure.

The Right Tools for the Job

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This image was created by and used with permission from @siggy, ©2019, All Rights Reserved.

Specific Tasks or Filtering

Think of a SPD as a filter, after all that is precisely what it is doing!

Type-1 is coarse and a work horse. These can handle strong heavy hits without breaking stride. This is your first line of defense, and in industrialized or areas prone to surges are highly recommended.

This will reduce the spike to a manageable level for the other filters downstream to capture without significant damage or loss of life. Remember joules?

Type-2 is medium filter and a good overall Whole House SPD. These are installed at the breaker panel.

Smaller additional units are very popular when paired with sub-panels for studio’s and home theaters.

They range in cost from $69.99 up to over $3k for some of the newer electronic systems.

Type-3 is a fine filter and a point-of-use SPD. When coupled with a Type-1 or 2 you have a sound network of protection. The composition of these units vary significantly and cost is a decent indicator.

But before we go further let’s touch on POWER STRIPS! These are often mistaken for a Type-3 SPD's. They look alike on the outside but offer no protection. The Item pictured below is an import for and sold by Granger Industrial. It’s intended for use in commercial and industrial (harsh) environments.

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These images are courtesy of @siggy, ©2019, All Rights Reserved.

Note the Black wire or Hot. It appears that a form of adhesive was used to make the connection. Also note the lack of support of the contact surfaces of the receptacles. This unit has a UL Listed label.

Home Stretch!


The Type-3 surge strip is one of the most commonly used and abused piece of electrical equipment.

We use them for everything including power tools and space heaters. Then that same SPD is used for a 3D printer or computer the very next day.

One of the biggest misconceptions is that a SPD will TRIP or disconnect power when a surge or fault occurs, or it will stop supplying power at the end of its life and thus informing you that replacement is needed. None of these is correct!

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The two outer images are courtesy of @siggy. The two inner images are royalty-free photos from iStock. ©2019, All Rights Reserved.

A Type-3 SPD for every application. Rack Mounts / Receptacles / Power Strips / Voice-Data-Video

Choosing the correct unit along with installation, will insure its proper use, function and will be ready when needed... Don’t forget your laundry rooms and microwaves!

It’s all about the MOV’S or Metal Oxide Varistors. Yes, plural because a quality unit will have multiple.

The MOV is the sacrificial component and gate, taking the pressure of the surge. These can range in size, voltage, and duration of exposure.

The TYPE-1 unit pictured above has two 52mm MOV’S compared to the 10mm yellow MOV’S below.

Note pictures 2 & 3 are decent SPD's and cost around $35-$40. Fused, multiple MOV’S (Yellow), and a thermal link (white) for each in case the MOV fails closed (fire hazard) also note the robust receptacle support and interior cap or cover to encase the buss and receptacles.

Last is a bargain unit. It is a joke, with only a single small MOV and more of that funny glue with a twist for a connection.

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These images are courtesy of @siggy, ©2019, All Rights Reserved.

Purchase A Quality & Trustworthy Unit

There are several units available today and most name brands offer a wide range of costs and features. They offer warranties and protection but read the fine print, and you will see that most are referring to White Goods or appliances for Type 1 & 2 units. Type-3 units will vary so choose only very reputable sources if you think you may need to file a claim. They are not in the habit of paying so you can be assured of a respectable unit. Cost is always a good indicator when choosing a SPD; you get what you pay for.

Some filters for Cable TV may disrupt channels operating at a certain shared frequency. Be sure to check for notes or disclaimers. A name brand that specializes in home theater will be a good choice, and also check the retailer's return policy if this becomes an issue.

I hope this answers some questions and dispels the myths regarding Surge Strips and Home Protection and leaves you confident in your choice of equipment.


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Author Profile: @siggy

@siggy is an industrial and automation electrician working for a major auto company in Detroit, MI.

He grew up with the great lakes outside his front door and has always lived within a few minutes walk. He is an avid boater and fisherman, and you can find him on the water regardless if it's frozen or soft.

He has been keeping fish on and off since the late 70's.